The aim was to analyze the locomtion and metabolic responses of professional players in the top three competitive standards of Spanish soccer during the four weeks before and after dismissal of the coach.
This study aimed to describe the worst-case scenarios (WCS) of professional soccer players by playing position in different durations and analyse WCS considering different contextual variables (match half, -location and outcome)
As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases.
Following studies were retrieved for this week:
#1 Relationship between movement dysfunctions and sports injuries according to gender of youth soccer player
Reference: J Exerc Rehabil. 2020 Oct 27;16(5):427-431. doi: 10.12965/jer.2040650.325. eCollection 2020 Oct.
Authors: Ki-Hoon Lim, Tae-Beom Seo, Young-Pyo Kim
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7609848/pdf/jer-16-5-427.pdf
Summary: The purpose of this study is to investigate relationship between movement dysfunctions and sports injuries according to gender of youth soccer player. Thirty-eight middle school soccer players participated in this study and they were divided into male (n=19) and female (n=19) groups. The Functional Movement Screen (FMS) and the Quadriceps-angle (Q-angle) during single-leg squat were analyzed for identifying imbalance and asymmetry of the body, and sports injury questionnaire was examined for 6 months after FMS test. The number of sports injuries did not show significant difference between youth male and female soccer athletes. In FMS results, the scores of overhead squat, hurdle step, in-line lunge, shoulder mobility, active straight leg raise, and rotary stability and the total scores were no significant differences between gender, but the score for the trunk stability push-up was significantly higher in male group than female group. There was no significant difference of Q-angle values between the left and right legs, but Q-angle value between youth male and female groups significantly showed interaction. Therefore, the present data suggested that FMS and Q-angle during single-leg squat might be indicators to predict and/or prevent sports injury in youth male and female soccer players.
#2 Can Small-side Games Provide Adequate High-speed Training in Professional Soccer?
Reference: Int J Sports Med. 2020 Nov 11. doi: 10.1055/a-1293-8471. Online ahead of print.
Authors: Jose Asian-Clemente, Alberto Rabano-Muñoz, Borja Muñoz, Jesus Franco, Luis Suarez-Arrones
Summary: The aim was to compare the running activity in official matches with that achieved in two small-sided games, designed with the same relative area per player but with different constraints and field dimensions, aiming to stimulate high-speed and very-high-speed running. Seventeen young professional players played one 5 vs. 5+5 with 2 floaters, varying in terms of whether there was a change of playing area (SSGCA) or not change (SSGNC). Running activity was monitored using GPS and the following variables were recorded: total distance covered; high-speed distance (18-21 km·h-1); very high-speed distance (>21 km·h-1); peak speed; accelerations and decelerations between 2-3 m·s-2 and above 3 m·s-2. SSGCA achieved statistically higher total distance, high-speed, peak speed and number of accelerations and decelerations than SSGNC (large to small magnitude). Both drills showed statistically greater high speed, number of accelerations and decelerations than official matches (large to small magnitude). Moreover, SSGCA exhibited statistically more total distance and distance at higher speed than official matches (moderate and small magnitude, respectively). In contrast, official matches showed statistically higher peak speeds than both training tasks and more very high speed than SSGNC (large and moderate magnitude, respectively). Coaches could use SSGCA to promote greater running activity in soccer players.
#3 Concussions in Soccer: An Epidemiological Analysis in the Pediatric Population
Reference: Orthop J Sports Med. 2020 Oct 21;8(10):2325967120951077. doi: 10.1177/2325967120951077. eCollection 2020 Oct.
Authors: Kiran Chatha, Taylor Pruis, Carlos Fernandez Peaguda, Eric Guo, Sandra Koen, Danielle Malone, Vani Sabesan
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7588758/pdf/10.1177_2325967120951077.pdf
Summary: As the popularity of youth soccer has increased in the United States, more attention has been focused on the effect of concussion injuries, with recent debate on whether heading should be disallowed. There is little evidence examining the epidemiology of these injuries. The purpose of this study was to examine the prevalence and incidence of youth soccer-related concussions. We hypothesized that concussion rates will correlate with increased participation in youth soccer. The National Electronic Injury Surveillance System was used to collect data on concussion injuries that occurred during soccer in pediatric patients from 2008 through 2016. Soccer-related concussion injuries were identified using specific codes and were analyzed for variation in disposition. The types of contact were categorized into player-to-player, head-to-ball, player-to-post, and player-to-ground contacts. Contact types related to hospitalization were subanalyzed. A weighted total of 3285 concussion injuries were identified during the study period, with an average of 386 concussions each year. The average age was 13.5 years, and there were no differences seen in incidence between the sexes. The overall incidence of concussion injuries increased (r = 0.789), while hospitalizations decreased (r = -0.574). The most common cause of concussion was found to be player-to-player contact, followed by head-to-ground contact and then head-to-ball contact. Subanalysis showed that 13% of hospitalizations were due to head-to-ball contact, compared with 39% and 44% due to player-to-player contact and head-to-ground contact, respectively. The relative risk of hospitalization from a concussion due to head-to-ball contact was 7.06 compared with 22.60 due to head-to-ground contact. The incidence of concussion in youth soccer has been increasing over the past decade as predicted, given the growing participation rates in both male and female soccer players. The most common cause of concussion was player-to-player contact, and the majority of concussions resulting in hospitalization occurred because of head-to-ground contact.
#4 Acute Physiological Responses to High-Intensity Resistance Circuit Training vs. Traditional Strength Training in Soccer Players
Reference: Biology (Basel). 2020 Nov 7;9(11):E383. doi: 10.3390/biology9110383.
Authors: Cristian Marín-Pagán, Anthony J Blazevich, Linda H Chung, Salvador Romero-Arenas, Tomás T Freitas, Pedro E Alcaraz
Download link: https://www.mdpi.com/2079-7737/9/11/383
Summary: The aim of this study was to evaluate and compare the cardiorespiratory and metabolic responses induced by high-intensity resistance circuit-based (HRC) and traditional strength (TS) training protocols. Ten amateur soccer players reported to the laboratory on four occasions: (1) protocol familiarization and load determination; (2) maximal oxygen consumption test; (3) and (4) resistance training protocols (HRC and TS), completed in a cross-over randomized order. In both protocols, the same structure was used (two blocks of 3 sets × 3 exercises, separated by a 5-min rest), with only the time between consecutive exercises differing: TS (3 min) and HRC (~35 s, allowing 3 min of local recovery). To test for between-protocol differences, paired t-tests were applied. Results showed that oxygen consumption and heart rate during HRC were 75% and 39% higher than TS, respectively (p < 0.001). After the training sessions, blood lactate concentration at 1.5, 5 and 7 min and excess post-exercise oxygen consumption were higher in HRC. The respiratory exchange ratio was 6.7% greater during HRC, with no between-group differences found post-exercise. The energy cost of HRC was ~66% higher than TS. In conclusion, HRC training induces greater cardiorespiratory and metabolic responses in soccer players and thus may be a time-effective training strategy.
#5 Exploring the Relationship Between Participation in an Adult-women's Soccer League and Intimate Partner Violence in Rural Kenya
Reference: J Interpers Violence. 2020 Nov 1;886260520969241. doi: 10.1177/0886260520969241. Online ahead of print.
Authors: Francis Barchi, Samantha C Winter, Daniel Mbogo, Bendettah Thomas, Brittany Ammerman
Download link: https://journals.sagepub.com/doi/pdf/10.1177/0886260520969241
Summary: Rates of intimate partner violence (IPV) against women in Sub-Saharan Africa are among the highest of any region in the world. Empirical studies on the effectiveness of IPV-prevention programs in Africa, though few, suggest that successful programs have emphasized community-level engagement and attitudinal change around gender roles. This study explored the relationship between adult women's participation in an all-women's soccer league and IPV in rural Kenya. Nikumbuke Project is a health- and literacy-based program for 702 women in Kwale County, Kenya, that also hosts a women's soccer league. A total of 684 Nikumbuke members completed surveys for this study, 543 of whom identified as having had a partner in the preceding 12 months and were included in this analysis. Participants in the study were, on average, in their late 30s, married with 4-6 children, a primary education or less, and no source of formal employment. Logistic regression models examined the association between a woman's participation in the soccer league and the odds that she would have experienced recent IPV, controlling for other covariates. Women who played on soccer teams had 59% lower odds of reporting physical IPV in the preceding 12 months and approximately 43% lower odds of reporting any form of IPV during the same period compared to women who did not play soccer. Support of more gender-equitable norms was associated with lower odds of all forms of recent violence. More research is needed to identify the underlying reasons for these observed effects and to determine the presence of a causal or temporal relationship between adult women's sports and IPV-risk reduction. Nonetheless, findings from this study point to a novel IPV intervention in communities that might otherwise be resistant to more overt attempts to address gender-based violence (GBV) or where social service agencies with the capacity for IPV-prevention programming may be limited.
#6 The Acute Effects of Cognitive-Based Neuromuscular Training and Game-Based Training on the Dynamic Balance and Speed Performance of Healthy Young Soccer Players: A Randomized Controlled Trial
Reference: Games Health J. 2020 Nov 9. doi: 10.1089/g4h.2020.0051. Online ahead of print.
Authors: Murat Emirzeoğlu, Özlem Ülger
Summary: The aim of this study was to investigate the acute effects of cognitive and game-based trainings (GBT) on dynamic balance (DB) and speed performance (SP) in healthy young soccer players. Forty-nine male soccer players were divided into three groups: cognitive-based neuromuscular training (CBNT; n = 16; age = 16.93 ± 1.18 years; body mass index [BMI] = 21.37 ± 1.57 kg/m2) group, GBT (n = 17; age = 17.05 ± 1.39 years; BMI = 21.10 ± 0.97 kg/m2) group, and control group (n = 16; age = 16.75 ± 1.12 years; BMI = 21.95 ± 1.36 kg/m2). The athletes in CBNT and GBT groups took part in one session lasting 1 hour. The Star Excursion Balance Test and the Speed Dribbling Test were used to evaluate DB and SP, respectively. The measurements were taken just before and after the trainings. Statistical analysis of the study was performed using SPSS 22.0 software (Statistical Package for Social Sciences, Inc., Chicago, IL). The Paired Student's t-test and Wilcoxon test were used. For in-group evaluation the ANOVA test was used for comparisons between the three groups. The Tukey's test was used for post hoc analysis. DB significantly improved in all directions in the GBT group (P < 0.05). Also, significant improvements were observed in DB in all directions except anterior, anterolateral, and anteromedial in the CBNT group, and except anterior, medial, and anteromedial directons in the control group (P < 0.05). SP significantly developed just in the CBNT and GBT groups (P = 0.001, P = 0.003, respectively). CBNT and GBT improved the DB of soccer players by 9.6% and 9.5%, respectively. Also, trainings improved the SP by 3.1% and 2.6%, respectively. CBNT and GBT are promising trainings that can improve DB and SP of healthy young soccer players.
#7 Characterization of On-Field Head Impact Exposure in Youth Soccer
Reference: J Appl Biomech. 2020 Nov 3;1-7. doi: 10.1123/jab.2020-0071. Online ahead of print.
Autors: Brian T Tomblin, N Stewart Pritchard, Tanner M Filben, Logan E Miller, Christopher M Miles, Jillian E Urban, Joel D Stitzel
Summary: The objective of this research was to characterize head impacts with a validated mouthpiece sensor in competitive youth female soccer players during a single season with a validated mouthpiece sensor. Participants included 14 youth female soccer athletes across 2 club-level teams at different age levels (team 1, ages 12-13 y; team 2, ages 14-15 y). Head impact and time-synchronized video data were collected for 66 practices and games. Video data were reviewed to characterize the type and frequency of contact experienced by each athlete. A total of 2216 contact scenarios were observed; heading the ball (n = 681, 30.7%) was most common. Other observed contact scenarios included collisions, dives, falls, and unintentional ball contact. Team 1 experienced a higher rate of headers per player per hour of play than team 2, while team 2 experienced a higher rate of collisions and dives. A total of 935 video-verified contact scenarios were concurrent with recorded head kinematics. While headers resulted in a maximum linear acceleration of 56.1g, the less frequent head-to-head collisions (n = 6) resulted in a maximum of 113.5g. The results of this study improve the understanding of head impact exposure in youth female soccer players and inform head impact exposure reduction in youth soccer.
#8 Residual deficits in reactive strength indicate incomplete restoration of athletic qualities following anterior cruciate ligament reconstruction in professional soccer players
Reference: J Athl Train. 2020 Nov 5. doi: 10.4085/169-20. Online ahead of print.
Authors: Paul J Read, William T Davies, Chris Bishop, Sean Mc Auliffe, Mathew G Wilson, Anthony N Turner
#9 Prediction of Somatotype from Bioimpedance Analysis in Elite Youth Soccer Players
Reference: Int J Environ Res Public Health. 2020 Nov 5;17(21):8176. doi: 10.3390/ijerph17218176.
Authors: Francesco Campa, Catarina N Matias, Pantelis T Nikolaidis, Henry Lukaski, Jacopo Talluri, Stefania Toselli
Summary: The accurate body composition assessment comprises several variables, causing it to be a time consuming evaluation as well as requiring different and sometimes costly measurement instruments. The aim of this study was to develop new equations for the somatotype prediction, reducing the number of normal measurements required by the Heath and Carter approach. A group of 173 male soccer players (age, 13.6 ± 2.2 years, mean ± standard deviation; body mass index, BMI, 19.9 ± 2.5 kg/m2), members of the academy of a professional Italian soccer team participating in the first division (Serie A), participated in this study. Bioelectrical impedance analysis (BIA) was performed using the single frequency of 50 kHz and fat-free mass (FFM) was calculated using a BIA specific, impedance based equation. Somatotype components were estimated according to the Heath-Carter method. The participants were randomly split into development (n = 117) and validation groups (n = 56). New anthropometric and BIA based models were developed (endomorphy = -1.953 - 0.011 × stature2/resistance + 0.135 × BMI + 0.232 × triceps skinfold, R2 = 0.86, SEE = 0.28; mesomorphy = 6.848 + 0.138 × phase angle + 0.232 × contracted arm circumference + 0.166 × calf circumference - 0.093 × stature, R2 = 0.87, SEE = 0.40; ectomorphy = -5.592 - 38.237 × FFM/stature + 0.123 × stature, R2 = 0.86, SEE = 0.37). Cross validation revealed R2 of 0.84, 0.80, and 0.87 for endomorphy, mesomorphy, and ectomorphy, respectively. The new proposed equations allow for the integration of the somatotype assessment into BIA, reducing the number of collected measurements, the instruments used, and the time normally required to obtain a complete body composition analysis.
#10 Potential prognostic factors for hamstring muscle injury in elite male soccer players: A prospective study
Reference: PLoS One. 2020 Nov 9;15(11):e0241127. doi: 10.1371/journal.pone.0241127. eCollection 2020.
Authors: Ismet Shalaj, Masar Gjaka, Norbert Bachl, Barbara Wessner, Harald Tschan, Faton Tishukaj
Download link: https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0241127&type=printable
Summary: Hamstring injuries remain the most common injury type across many professional sports. Despite a variety of intervention strategies, its incidence in soccer players playing in the UEFA Champions League has increased by 4% per year over the last decade. Test batteries trying to identify potential risk factors have produced inconclusive results. The purpose of the current study was to prospectively record hamstring injuries, to investigate the incidence and characteristics of the injuries, and to identify possible risk factors in elite male soccer players, playing in the Kosovo national premier league. A total of 143 soccer players from 11 teams in Kosovo were recruited. To identify possible prevalent musculoskeletal or medical conditions a widespread health and fitness assessment was performed including isokinetic strength testing, Nordic hamstring strength test, functional tests, and a comprehensive anamnesis surveying previous hamstring injuries. On average 27.9% of the players sustained at least one hamstring injury with three players suffering bilateral strains with the re-injury rate being 23%. Injured players were significantly older and heavier and had a higher body mass index compared to non-injured ones (p < 0.05). There was a lower passing rate in the Nordic hamstring strength test and a higher injury incidence among the previously injured players compared to non-injured ones (p < 0.05). Except for hamstring/quadriceps ratio and relative torque at 60°/sec (p < 0.05) for dominant and non-dominant leg, there were no other significant differences in isokinetic strength regardless of the angular velocity. No differences were observed for functional tests between cohorts. Regression analysis revealed that age, Nordic hamstring strength test, previous injury history, and isokinetic concentric torque at 240°/sec could determine hamstring injuries by 25.9%, with no other significant predicting risk factors. The battery of laboratory and field-based tests performed during preseason to determine performance related skills showed limited diagnostic conclusiveness, making it difficult to detect players at risk for future hamstring injuries.
#11 Perceptions of Stress of Swedish Volunteer Youth Soccer Coaches
Reference: Sports (Basel). 2020 Nov 3;8(11):E146. doi: 10.3390/sports8110146.
Authors: Krister Hertting, Stefan Wagnsson, Karin Grahn
Download link: https://www.mdpi.com/2075-4663/8/11/146
Summary: The work of a coach can be stressful, and little is known about how volunteer coaches in child and youth soccer perceive stress. Therefore, the overall aim of this study was to explore perceptions of stress among Swedish volunteer youth soccer coaches. An online questionnaire was distributed to 1514 soccer coaches of which 688 (78% men and 22% women; 4% < 30 years, 34% 31-40 years; 57% 41-50 years and 5% > 51 years) with non-profit positions responded. Findings indicate that participants in general do not feel excessively stressed by being a volunteer youth soccer coach (M = 2.20; SD = 0.93; Min = 1; Max = 5), and no significant differences in perceived stress level were found based on gender, age, ethnicity, educational level or occupation. Multiple regression analysis showed that demands from employment (β = 0.24, p < 0.001), difficulty catching up with the family (β = 0.22, p < 0.001), not having enough time to plan activities (β = 0.13, p < 0.001), feeling pressured when selecting the team (β = 0.09, p = 0.013) and own demands to achieve good results (β = 0.07, p = 0.045), significantly contributed to perceptions of stress among the investigated youth sport coaches. The results shed light on the important aim that sport clubs develop holistic strategies when recruiting and retaining coaches and for other functions concerning child and youth soccer teams.
#12 Differences in physical fitness after an 8-week preseason training among elite football players aged 17-19 years
Reference: J Exerc Rehabil. 2020 Oct 27;16(5):442-449. doi: 10.12965/jer.2040598.299. eCollection 2020 Oct.
Authors: Hojun Lee, Chang-Hwa Joo
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7609845/pdf/jer-16-5-442.pdf
Summary: There may be an optimal period of time to maximize the improvement of physical fitness during adolescence. The aim of this study was to examine the magnitude of changes in physical fitness after 8 weeks of preseason training according to chronological ages after the age at peak high velocity. Thirty male young football players from an elite football team (U-16, n=10; U-17, n=10; U-18, n=10) participated in the study. The players completed an 8-week general preseason football training and participated in the pre- and posttests to measure physical fitness. The 8-week preseason training improved the power of all young players (P<0.05). The 20-m sprint performance was improved by training in U-16 and U-18 (P<0.05), but no changes were found in the U-17 group (P>0.05). Significant differences were found in the arrowhead left in U-16 and U-18 (P<0.05) after training; however, no difference was observed in U-17 (P>0.05). Coordination was enhanced further in U-16 and U-17 (P<0.05) compared with that in U-18 (P>0.05). The performance of repeated sprints and Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1) were similar between pre- and posttraining in all age groups (P>0.05). Collectively, the results emphasized the importance of systematic and scientific training methods to improve the fitness levels of young football players in the preseason training period. Moreover, training to improve coordination in young football players is effective at younger ages.
#13 What Do Football Players Look at? An Eye-Tracking Analysis of the Visual Fixations of Players in 11 v 11 Elite Football Match Play
Reference: Front Psychol. 2020 Oct 16;11:562995. doi: 10.3389/fpsyg.2020.562995. eCollection 2020.
Authors: Karl Marius Aksum, Lukas Magnaguagno, Christian Thue Bjørndal, Geir Jordet
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7596273/pdf/fpsyg-11-562995.pdf
Summary: Current knowledge of gaze behavior in football has primarily originated from eye-tracking research in laboratory settings. Using eye-tracking with elite players in a real-world 11 v 11 football game, this exploratory case study examined the visual fixations of midfield players in the Norwegian premier league. A total of 2,832 fixations by five players, aged 17-23 years (M = 19.84), were analyzed. Our results show that elite football midfielders increased their fixation duration when more information sources became available to them. Additionally, participants used shorter fixation durations than previously reported in laboratory studies. Furthermore, significant differences in gaze behavior between the attack and defense phases were found for both areas of interest and fixation location. Lastly, fixation locations were mainly on the ball, opponent, and teammate category and the player in possession of the ball. Combined, the results of this study enhance the knowledge of how elite footballers use their vision when playing under actual match-play conditions. They also suggest that laboratory designs may not be able to capture the dynamic environment that footballers experience in competition.
#14 Effects of a 10 vs. 20-Min Injury Prevention Program on Neuromuscular and Functional Performance in Adolescent Football Players
Reference: Front Physiol. 2020 Oct 15;11:578866. doi: 10.3389/fphys.2020.578866. eCollection 2020.
Authors: Anna Lina Rahlf, Cornelius John, Daniel Hamacher, Astrid Zech
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7593709/pdf/fphys-11-578866.pdf
Summary: Regular injury prevention training is not only effective in reducing sports injury rates, but also in improving neuromuscular and performance-related variables. However, it is currently unknown if this effect can be modified by varying the training dosage. The objective was t compare the effects of two injury prevention programmes with a different training duration on neuromuscular control and functional performance in adolescent football players. 342 (15.4 ± 1.7 years) male football players from 18 teams were initially included. The teams were cluster-randomized into two intervention groups. Both groups performed an injury prevention program twice a week during one football season (10 months) using the same exercises but a different duration. One intervention group (INT10, n = 175) performed the program for 10 min, while the other intervention group (INT20, n = 167) for 20 min. At the beginning and end of the season, balance control (Balance Error Scoring System = BESS), jump performance (Squat Jump, Countermovement Jump) and flexibility (Sit and Reach Test, ankle flexibility, hip flexibility) tests were performed. For the final analysis, nine teams with 104 players were considered. Significant group by time interactions were found for the sit and reach test (p < 0.001) and ankle flexibility (p < 0.001) with higher improvements in the INT20 group. Improvements over the period of one season but no group differences were found for the BESS, Squat Jump and hip flexibility. Within a single training session, performing structured neuromuscular training with a longer duration is more effective than a shorter duration for improving lower extremity flexibility.
This study aimed to evaluate commonly used methods to assess BMS within a highly selected sample of youth soccer players.
The aim of this study was to investigate position-specific endurance performance of soccer players.
As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases.
Following studies were retrieved for this week:
#1 Effect of Playing Position, Match Half, and Match Day on the Trunk Inclination, G-Forces, and Locomotor Efficiency Experienced by Elite Soccer
Players in Match Play
Reference: Sensors (Basel). 2020 Oct 14;20(20):E5814. doi: 10.3390/s20205814.
Authors: José M Oliva-Lozano, Elisa F Maraver, Víctor Fortes, José M Muyor
Download link: https://www.mdpi.com/1424-8220/20/20/5814
Summary: The rapid growth of wearable sensors has allowed the analysis of trunk kinematics during the match, which is necessary for having a better understanding of the postural demands of soccer players. However, some contextual variables may have an impact on the physical demands of the players. This study aimed to analyze the effect of three contextual variables (playing position, match half, and match day) on the sagittal trunk inclination, G-forces, and locomotor efficiency experienced by soccer players in match play. Then, wearable sensors were used to collect the trunk kinematics during 13 matches. Firstly, positional differences were found on the trunk inclination (p = 0.01) and the G-forces experienced by the players (p < 0.001). For example, the greatest and lowest trunk inclination was found for FW (~34.01°) and FB (~28.85°) while the greatest and lowest G-forces were found for WMF (1.16 G) and CD (1.12 G), respectively. However, there were no positional differences in the locomotor efficiency (p = 0.10). Secondly, the match half had a significant effect on the trunk inclination (p = 0.01) and the G-forces experienced by the players (p < 0.001) with significantly lower values observed during the second half. No differences between halves were found on the locomotor efficiency for any playing position (p = 0.41). Finally, no significant effect of match day on any variable was observed. This investigation is one of the first steps towards enhancing the understanding of trunk kinematics from elite soccer players. The positional differences found on the trunk inclination and G-forces imply that the development of position-specific training drills considering the postural demands is necessary to prepare the players not only for the physical demands but also for successful performance in the field of regard. The resistance to fatigue needs to be trained given the differences between halves.
#2 The use of a running power-meter for performance analysis in five-a-side football
Reference: Gait Posture. 2020 Sep 30;83:35-43. doi: 10.1016/j.gaitpost.2020.09.028. Online ahead of print.
Authors: Paul W Macdermid, Tom Pearce, Andrew Foskett
Summary: Power output considers all movement aspects of the game of football and could have meaningful impact for teams. The aim was to assess inter-reliability of ten power meters designed for running; and as a descriptor of individual and team performance during a five-a-side football match. The work aimed to assess inter-device reliability of running power-meters combined with data analysis from intermittent running, along with descriptives of player work rate, gait and team performance during a small-sided game of football. 10 different running power meters inter-reliability were on a treadmill at 8, 10, 12, and 16 km h-1 for 60 s in a random order. Football players (N = 10) performed the Yo-Yo ET1 with the running power meters to determine participants' endurance capability, while assessing the ability to record metrics of gait and power output during intermittent running. Following a period of 7-days participants took part in a 20 min small-sided game of football wearing the running power meters to provide descriptors of work and gait. Good inter-device reliability for the power meters (CV 1.67, range 1.51-1.94 %) during continuous treadmill running were found. Overall mean ± SD results for Yo-Yo ET1 power output 263 ± 36W, power:weight 3.59 ± 0.34W∙kg-1 significantly (p < 0.05) increased with successive stages, while ground-contact time 234 ± 17 ms, and vertical oscillation 90.7 ± 27 mm did not change (p > 0.05). Descriptive analysis of the small-sided game presented mean ± SD absolute and relative power outputs of 148 ± 44W and 1.98 ± 0.53W∙kg-1, equating to 54 ± 21 %Wmax and 74 ± 5%HRmax. Characteristics of gait included cadence 125 ± 22 rpm, ground contact time 266 ± 19 ms, and vertical oscillation 76.7 ± 7 mm. The winning team worked relatively harder than the losing team (53.3 ± 0.7 %Wmax vs 46.7 ± 0.4 %Wmax, p < 0.0001) with more time (398 s vs 141 s) spent above 70 %Wmax.
#3 Attitudes, beliefs and factors influencing football coaches' adherence to the 11+ injury prevention programme
Reference: BMJ Open Sport Exerc Med. 2020 Sep 24;6(1):e000830. doi: 10.1136/bmjsem-2020-000830. eCollection 2020.
Authors: Julie Shamlaye, Luboš Tomšovský, Mark L Fulcher
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7525254/pdf/bmjsem-2020-000830.pdf
Summary: The purpose was to explore football coaches' beliefs and attitudes about injury prevention and the 11+ injury prevention programme, and to investigate factors that may influence adherence to the 11+ injury prevention programme. A total of 538 football coaches who had completed an injury prevention education workshop were invited to participate in a web-based nationwide survey. The survey questions explored beliefs and attitudes about injury prevention and the 11+ injury prevention programme, self-reported adherence to the 11+ programme, as well as perceived barriers and facilitators to the use of the 11+ programme. There were 158 respondents. The majority believe that injury prevention is part of their coaching role (94%) that a structured warm-up is an important part of their team's preparation for training and games (96%), and that the 11+ is effective (92%). While most respondents (95%) use the 11+, modifications are common. Participants with greater coaching experience are more likely to use the programme. Time constraints are the main barriers to adherence, while knowing that the programme enhances performance is seen as a major facilitator. Coaches who attended an injury prevention workshop have positive attitudes towards injury prevention and the 11+ programme. However, coaches with less coaching experience may be less likely to use the 11+ and could therefore be the target population for future education workshops. Promoting the performance enhancing effects of the 11+ and encouraging modifications could improve acceptability and adherence.
#4 Mechanisms explaining the birthplace effect for male elite football players
Reference: J Sports Sci. 2020 Oct 21;1-7. doi: 10.1080/02640414.2020.1835237. Online ahead of print.
Authors: Michiel H H van Nieuwstadt, Marjolijn Das, Marije T Elferink-Gemser
Summary: Earlier research shows that wide regional variations exist in the success of athletes' talent development but is divided with respect to the role of urbanity: both low and high urbanity have been identified as settings that contribute to the presence of talent hotspots. In this article, we intend to provide more insight into the role of urbanity in talent development in Dutch football. We used public data on the regional background of male elite players (N = 825) and combined this with public data on municipal characteristics from Statistics Netherlands and other sources: urbanity, football participation, instructional resources and population composition effects (migration background and income of inhabitants). Linear regression analysis showed that football participation, the proportion of non-western migrants and median income predict "talent yield", i.e., the proportion of young people that reach an elite level in a municipality. Urbanity does not have an independent influence when the proportion of non-western migrants in the municipality is taken into account. The presence of instructional resources does not have an independent influence. The results suggest that characteristics of the built environment, such as indoor and outdoor play opportunities, may be less influential in talent development than previously assumed.
#5 Short-Term Effect of Ankle Eversion Taping on Bilateral Acute Ankle Inversion Sprains in an Amateur College Football Goalkeeper: A Case Report
Reference: Healthcare (Basel). 2020 Oct 15;8(4):E403. doi: 10.3390/healthcare8040403.
Authors: Jung-Hoon Lee
Download link: https://www.mdpi.com/2227-9032/8/4/403
Summary: This case study aimed to investigate the short-term effects of ankle eversion taping (AET) using kinesiology tape on bilateral acute ankle inversion sprains in an amateur college soccer goalkeeper. Ankle eversion taping was applied for two weeks (average 16 h/day) on a 24-year-old goalkeeper with bilateral grade 2 acute ankle inversion sprain with swelling (left ankle more severe) during a soccer match. The subject had a foot ankle outcome score (FAOS) of 41%; visual analog scale (VAS) scores of 5/10 and 7/10 for the right and left ankles, respectively; patient-specific functional and pain scale (PSFS) score of 12/50; and limited range of motion of the ankle. The swelling disappeared after AET in both ankles. In the weight-bearing lunge test, the right and left ankle distances increased from 2 cm to 12 cm, and from 0 cm to 12 cm, respectively. The FAOS improved from 20% to 97%, while the PSFS score improved from 12/50 to 50/50. The VAS scores decreased to 0/10 for both ankles. AET is a potential clinical treatment method for acute ankle inversion sprain with swelling.
#6 How Successful Are the Teams of the European Football Elite off the Field?-CSR Activities of the Premier League and the Primera División
Reference: Int J Environ Res Public Health. 2020 Oct 16;17(20):7534. doi: 10.3390/ijerph17207534.
Authors: Kinga Ráthonyi-Ódor, Éva Bácsné Bába, Anetta Müller, Zoltán Bács, Gergely Ráthonyi
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7589622/pdf/ijerph-17-07534.pdf
Summary: In the past two decades the sports sector has turned its attention to understanding the idea of sustainability, particularly to the practical steps related to this. The purpose of this study is to investigate the nature of CSR (corporate social responsibility) activities carried out by teams playing in the Premier League and the Primera División in the 2018/2019 season, and how these CSR actions serve environmental protection and society, manifesting the concept of sustainable development. We applied comparative analysis based on secondary databases. We examined the available reports regarding all the 40 teams, focusing on information about their CSR aspirations and related academic research results, and we worked out specific criteria to evaluate environmentally and socially related CSR activities. Arsenal and Real Madrid were chosen to show good practices that can serve as examples for the other members of the sports sector. At Premier League clubs, the practical application of the CSR activities has been intensively developed. Clubs share detailed statistical information about their actions, while some of the clubs even publish their future plans. The quantity and detail of the information found with Primera División clubs is rather varied. Some clubs introduce their CSR activities in full detail; however, in the case of most clubs, the accessible information is rather superficial and lacks any exact descriptions. The findings clearly show that the sports world is consciously shifting towards the realization of sustainable development, which requires a comprehensive reconnection of sporting society and an increase in awareness in order to achieve the efficient and successful integration of CSR activities into sport.
#8 The sound of silence in association football: Home advantage and referee bias decrease in matches played without spectators
Reference: Eur J Sport Sci. 2020 Nov 1;1-21. doi: 10.1080/17461391.2020.1845814. Online ahead of print.
Authors: Fabrizio Sors, Michele Grassi, Tiziano Agostini, Mauro Murgia
Summary: Home advantage and referee bias are two well-documented phenomena in professional sports, especially in association football. Among the various factors determining them, the crowd noise is considered as one of the most relevant; yet, the majority of previous studies could not isolate its contribution. The possibility to study the effects of crowd noise - or, better, of its absence - in an ecological context was given by the matches played behind closed doors due to the COVID-19 pandemic. The aim of the present study was to investigate whether home advantage and referee bias still occur (and to what extent) during matches played in absence of spectators. In particular, the focus was on the first and second divisions of the top four countries in the UEFA ranking, for a total of 841 matches behind closed doors. The hypothesis was that, if these phenomena are largely due to the effect of crowd noise, the absence of spectators should reduce their occurrence. Various parameters for each of the two phenomena were considered, and the analyses revealed a reduction of home advantage and the absence of referee bias. The results bring further support to the claim that, among all the factors contributing to home advantage and referee bias, crowd noise has a relevant role. Thus, spectators can significantly contribute to determine the dynamics and the outcomes of professional football matches.
#9 Special Issue on Concussion Biomechanics in Football
Reference: Ann Biomed Eng. 2020 Nov 3. doi: 10.1007/s10439-020-02653-3. Online ahead of print.
Authors: Bethany Rowson, Stefan M Duma
Download link: https://link.springer.com/article/10.1007%2Fs10439-020-02653-3
#10 Athlete workloads during collegiate women's soccer practice: Implications for return-to-play
Reference: J Athl Train. 2020 Nov 5. doi: 10.4085/205-20. Online ahead of print.
Authors: Natalie Kupperman, Alexandra F DeJong, Peter Alston, Jay Hertel, Susan A Saliba
Summary: Athlete monitoring using wearable technology is often incorporated with soccer athletes. While evaluations have tracked global outcomes across soccer seasons, there is little information on athlete loads during individual practice drills. Understanding these demands is important for athletic trainers for return-to-play decision-making. The objective was to provide descriptive information on total distance, total playerload (PL), distance per minute, and PL per minute for practice drill structures and game-play by player position among female soccer athletes across a competitive season. Thirty-two female college soccer players (20±1 years) participated in this study. Athletes wore a single GPS and triaxial accelerometer unit during all practices and games in a single soccer season. Individual practice drills were labeled by the team's strength and conditioning coach, and binned into physical, technical and tactical skills, and small- and large-sided competition drill structures. Descriptive analyses were used to assess the median total distance, total PL, distance per minute, and PL per minute by drill structure and player position (defenders, midfielders, forwards/strikers) during practices and games. Small- and large-sided competitive drills imposed the greatest percentage of workload across all measures for each position (~20% of total practice), followed by physical drills. When comparing technical and tactical, technical skills required athletes to cover the greatest distance (technical: ~17%; tactical: ~15%), tactical skills required higher play intensity during practices across all positions (technical: ~18%; tactical: ~13%). Defenders had the highest median PL outcomes of all positions during practices. Different practice drill types imposed varying levels of demands on female soccer athletes, which simulated game play. Athletic trainers and other clinicians may use this information for formulating objective return-to-play guidelines for injured collegiate women's soccer players.
#11 The relationship between Isometric Mid-Thigh Pull variables and athletic performance measures: empirical study of english professional soccer players and meta-analysis of extant literature
Reference: J Sports Med Phys Fitness. 2020 Nov 4. doi: 10.23736/S0022-4707.20.11205-2. Online ahead of print.
Authors: Liam Mason, Andrew Kirkland, James Steele, James Wright
Summary: There is currently limited evidence available to support the use of the isometric mid thigh pull (IMTP) within professional soccer. The aim of this study was to analyse the association between IMTP variables, with common markers of athletic performance capability. Eleven professional development soccer players (age: 20 ± 2 years, stature: 1.82 ± 0.10 m, mass: 76.4 ± 12.8 kg) performed IMTP, 5 m and 10 m accelerations, maximal sprint speed (MSS), countermovement jump (CMJ), and the 505 change of direction test (COD). Relative and absolute Peak force (PF) and force at 50, 100, 150 and 200 ms values were measured during the IMTP. Relative F150, F200, PF displayed large to very large correlations with MSS (r = 0.51, r = 0.66, and r = 0.76 respectively), while absolute PF also displayed a large correlation with MSS (r = 0.57). Relative and absolute PF showed large correlations with CMJ height (r = 0.54 and r = 0.55 respectively). Relative F150 and F200 highlighted large correlations with COD ability (r = -0.68 and r = -0.60 respectively). Relative F200 and PF had a large negative correlation with 10m acceleration (r = -0.55 and r = -0.53 respectively). This study provides an important contribution to knowledge within the area of IMTP testing in professional soccer by evidencing the prominence of the isometric force generating capacity as an underpinning factor in relation to athletic capability.
#12 Effects of Strength vs. Plyometric Training on Change of Direction Performance in Experienced Soccer Players
Reference: Sports (Basel). 2020 Oct 30;8(11):E144. doi: 10.3390/sports8110144.
Authors: Håvard Guldteig Rædergård, Hallvard Nygaard Falch, Roland van den Tillaar
Download link: https://www.mdpi.com/2075-4663/8/11/144
Summary: The purpose of this study was to compare how 6 weeks of strength- vs. plyometric training, which were matched upon direction of motion and workload, influences change of direction (COD) performance. Twenty-one experienced male soccer players (age: 22.2 ± 2.7) were pair-matched into a strength- (n = 10) and a plyometric (n = 11) training group. CODs of 45°, 90°, 135° and 180° performed from either a 4 m or 20 m approach distance were compared before and after intervention. Results showed no significant difference between groups. Significant effects were only found within the plyometric training group (-3.2% to -4.6%) in 90°, 135° and 180° CODs from 4 m and a 180° COD from a 20 m approach distance. Individual changes in COD performances showed that with the 4 m approach at least 55% and 81% of the strength and plyometric training group, respectively, improved COD performance, while with the 20 m approach at least 66% of both groups improved performance. This study showed that the plyometric training program can improve most CODs, with angles over 90°, although this is dependent on the distance approaching the COD. Considering the limited time of implementing physical conditioning, in addition to regular soccer practice in most soccer environments, the current plyometric training program can be advantageous in improving CODs at maximal intensity.
#13 Purposeful Heading in Youth Soccer: A Review
Reference: Sports Med. 2020 Nov 3. doi: 10.1007/s40279-020-01376-8. Online ahead of print.
Authors: Victoria E Wahlquist, Thomas W Kaminski
Summary: Recent public concern over the short- and long-term effects of repetitive head impacts (RHI) associated with purposeful heading in soccer has led researchers to study a multitude of variables related to this important aspect of the game. Of particular interests are the effects of soccer heading in the youth population (≤ 13 years old) whose brains are undergoing rapid development. We conducted a review on youth soccer heading that includes purposeful heading frequency, head impact biomechanics, head injuries, clinical outcomes, and modifying factors. We have concluded that youth soccer players head the ball at a low frequency that typically increases with age and with a finding that boys head the ball more often than girls do. Interestingly, although girls head the ball less frequently than boys do, they tend to sustain higher head impact magnitudes. Head injuries are more likely to occur in girls versus boys and during games because of contact with another player. Clinical outcome measures of concussion are often utilized to study the effects of soccer heading, in both field and laboratory environments. Immediately following soccer heading, youth often report having a headache and demonstrate some deficits in balance measures. Modifying factors that may benefit soccer players participating in purposeful heading activities include stronger neck musculature, wearing headgear, and the use of mouthguards. Research involving youth soccer players needs to be expanded and funded appropriately to better understand the consequences of RHI in both the short and long term.
#14 Relationships Between Training Workload Parameters with Variations in Anaerobic Power and Change of Direction Status in Elite Youth Soccer Players
Reference: Int J Environ Res Public Health. 2020 Oct 29;17(21):E7934. doi: 10.3390/ijerph17217934.
Authors: Hadi Nobari, Luis Felipe Tubagi Polito, Filipe Manuel Clemente, Jorge Pérez-Gómez, Mina Ahmadi, Miguel Ángel Garcia-Gordillo, Ana Filipa Silva, Jose Carmelo Adsuar
Download link: https://www.mdpi.com/1660-4601/17/21/7934
Summary: The purpose of this study was to test the relationships between training workload (WL) parameters with variations in anaerobic power and change of direction (COD) in under-16 soccer players. Twenty-three elite players under 16 years were daily monitored for their WL across 20 weeks during the competition soccer season. Additionally, players were assessed three times for anthropometric, body composition, COD, and anaerobic power. A correlational analysis between the mean differences between assessments and accumulated WL parameters were conducted. Moreover, a regression analysis was executed to explain the variations in the percentage of change in fitness levels considering the accumulated WL parameters and peak height velocity. The accumulated daily loads during one week showed a large and a moderate correlation with peak power and COD at different periods of the season. Regression analysis showed no significant predictions for COD (F(12, 10) = 1.2, p = 0.41) prediction, acute load (F(12, 10) = 0.63, p = 0.78), or chronic load (F(12, 10) = 0.59, p = 0.81). In conclusion, it may be assumed that the values of the chronic workload and the accumulated training monotony can be used to better explain the physical capacities of young soccer players, suggesting the importance of psychophysiological instruments to identify the effects of the training process in this population.
#15 Coronavirus Disease-19 Quarantine Is More Detrimental Than Traditional Off-Season on Physical Conditioning of Professional Soccer Players
Reference: J Strength Cond Res. 2020 Oct 30. doi: 10.1519/JSC.0000000000003890. Online ahead of print.
Authors: Rafael Grazioli, Irineu Loturco, Bruno M Baroni, Gabriel S Oliveira, Vasyl Saciura, Everton Vanoni, Rafael Dias, Filipe Veeck, Ronei S Pinto, Eduardo L Cadore
Summary: Beyond the severe health crisis, the coronavirus disease 2019 has also affected the high-performance sports scenario. In soccer, practitioners are concerned about the effects of long-term detraining on players' conditioning, and caution is required when activities return. This study assessed body composition, jump and sprint performance, hamstring eccentric strength, and intermittent cardiorespiratory fitness of 23 male professional soccer players who returned to training activities after 63 days of quarantine. The results were compared with their physical condition assessed before a pre-season phase as soon as they returned to training after a regular 24-day off-season period. In comparison with after off-season assessments, the quarantine induced significant increases in body mass, body fat mass, 10- and 20-m sprint times as well as decreases in countermovement jump height (p < 0.05). There were no significant changes in hamstring eccentric strength, squat jump height, and cardiorespiratory fitness (p > 0.05). In summary, we showed that 63 days of quarantine impaired several physical performance measures compared with regular off-season in soccer players. Given the present results, special attention should be given to body composition-related and speed power-related capabilities after long-term detraining in professional soccer.
#16 Monitoring Training Load in Soccer: The ROMEI Model
Reference: J Strength Cond Res. 2020 Oct 30. doi: 10.1519/JSC.0000000000003875. Online ahead of print.
Authors: Marco Montini, Jacopo E Rocchi
Summary: For a training organization, monitoring training load (TL) is of paramount importance. Despite this, a conclusive response on such topic is yet to be reported. The aims of this study were to investigate the relationship between TL indicators and to propose a new method for monitoring TL response and physical fitness. Twenty professional soccer players were retrospectively evaluated. The first phase of data analysis included 34 in-season training sessions. Subsequently, three microcycles (T1-T2-T3) of pre-season training were processed. A regression model was used to examine the relationships between internal TL (session rating of perceived exertion [s-RPE]) and external TL (energy expenditure, EE). The standard error of the regression equation was used to propose a new model called "ROMEI" (Relation of Ongoing Monitored Exercise in Individual). The level of statistical significance was set at p < 0.05. During the competitive season and the pre-season training camp, the average TL values were 65.8 ± 22 and 58.2 ± 22 minutes; 336 ± 204 and 228 ± 101 AU of s-RPE; and 29 ± 13 and 25 ± 9 kJ kJ of EE, respectively. In the competitive season, the collective and average individual correlation coefficients between s-RPE and EE were r = 0.888 and r = 0.892 ± 0.05, respectively. Considering slope values (m) of the regression line, data highlighted a significant increase of +34.4 ± 15.9% in T2 vs. T3 (p < 0.001) and +38.2 ± 15.2% in T1 vs. T3 (p < 0.001). Data shown in this investigation support the use of an individualized analysis to better understand the TL administered to soccer players rather than a collective analysis. This may be accomplished with the proposed ROMEI model.
This study aimed to determine whether spikes in acute:chronic workload ratio (ACWR) are associated with injury incidence and to examine the differences in external load due to greater or lesser exposure to matches and the long-term effects of the load during a chronic seasonal period.
The aim was to determine whether prospectively measured components of valgus collapse during a deceleration cut can differentiate between female footballers who go on to non-contact ACL injury
As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases.
Following studies were retrieved for this week:
#1 Are goals scored just before halftime worth more? An old soccer wisdom statistically tested
Reference: PloSONE. 2020 Oct 20;15(10):e0240438. doi: 10.1371/journal.pone.0240438.
Authors: Henrich R Greve, Jo Nesbø, Nils Rudi, Marat Salikhov
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7575079/pdf/pone.0240438.pdf
Summary: There is an old soccer wisdom that a goal scored just before halftime has greater value than other goals. Many dismiss this old wisdom as just another myth waiting to be busted. To test which is right we have analysed the final score difference through linear regression and outcome (win, draw, loss) through logistic regression. We use games from many leagues, control for the halftime score, comparing games in which a goal was scored after 1 minute remained of regulation time with games in which it was scored before the 44th minute. Our main finding is that the home team scoring just before halftime influence these outcomes to its advantage, compared with scoring earlier with the same halftime score. We conclude that a goal scored just before halftime has greater value than other goals provided it is scored by the home team. In other words; the wisdom may be old, but it's still wise.
#2 Assessing Interlimb Jump Asymmetry in Young Soccer Players: The My Jump 2 App
Reference: Int J Sports Physiol Perform. 2020 Oct 19;1-9. doi: 10.1123/ijspp.2019-0981. Online ahead of print.
Authors: Matheus Barbalho, Ana Francisca Rozin Kleiner, Bianca Callegari, Ramon Costa de Lima, Givago da Silva Souza, Anselmo de Athayde Costa E Silva, Victor Silveira Coswig
Summary: Jumps are important evaluation tools for muscle strength and power and for interlimb asymmetries. Different jump tests are well related to athletic performance, prediction of injury risk, and common motor gestures of several sports such as soccer. Low-cost mobile applications (apps) have gained popularity for this measure. The authors hypothesized that the My Jump 2 app would be a valid tool to assess drop-jump performance and interlimb asymmetry in soccer players. Eleven male soccer players took part in this study (18.2 [1.3] y, 69.9 [9.5] kg, 174 [6.6] cm). The athletes performed each test twice on a force plate (gold-standard method), while the jumps were recorded through the mobile app. Measures with the My Jump 2 app were applied by 2 evaluators, independently and in duplicate (interrater and intrarater reliability). The agreement analysis between both evaluations was done using an intraclass correlation coefficient and Bland-Altman plots. Compared with the force platform, the app tested showed excellent reliability for the drop jump's flight time and interlimb asymmetry (intraclass correlation coefficient > .98). For interlimb contact-time asymmetry, the values were 18.4 (9.9) and 19.1 (9.9) milliseconds for the My Jump 2 app and the force platform, respectively (P = .88). For flight-time asymmetries, the values were 389.7 (114.3) and 396.8 (112.5) milliseconds for the My Jump 2 app and the force platform, respectively (P = .88). The My Jump 2 app is a valid tool to assess drop-jump and interlimb asymmetry in soccer players.
#3 Soccer-Related Concussions Among Swedish Elite Soccer Players: A Descriptive Study of 1,030 Players
Reference: Front Neurol. 2020 Sep 23;11:510800. doi: 10.3389/fneur.2020.510800. eCollection 2020.
Authors: Sofie Hänni, Fredrik Vedung , Yelverton Tegner, Niklas Marklund, Jakob Johansson
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7538773/pdf/fneur-11-510800.pdf
Summary: There are growing concerns about the short- and long-term consequences of sports-related concussion, which account for about 5-9% of all sports injuries. We hypothesized there may be sex differences in concussion history and concussion-related symptoms, evaluated among elite soccer players in Sweden. Soccer players (n = 1,030) from 55 Swedish elite soccer teams participated in this study. Questionnaires were completed prior to the start of the 2017 season. Player history of soccer-related concussion (SoRC), symptoms and management following a SoRC were evaluated. Before the start of the season the players completed a baseline questionnaire assessing previous concussions. The Sports Concussion Assessment Tool 3 was included with regard to symptom evaluation. Out of 993 responding players 334 (34.6%) reported a previous SoRC and 103 players (10.4%) reported a SoRC during the past year. After sustaining a SoRC, 114 players (34.2%) reported that they continued their ongoing activity without a period of rest, more commonly female (44.9%) than male players (27.7%; P = 0.002). Symptom resolution time was 1 week or less for 61.3% of the players that reported having persisting symptoms. A positive correlation was observed between number of previous concussions and prevalence of three persisting symptoms: fatigue (P < 0.001), concentration/memory issues (P = 0.002) and headache (P = 0.047). About 35% of male and female elite soccer players in Sweden have experienced a previous SoRC, and about 10% experienced a SoRC during the last year. Female players continued to play after a SoRC, without a period of rest, more often than males. A higher risk of persisting symptoms was observed in players with a history of multiple concussions.
#4 The Academic Background of Youth Soccer Coaches Modulates Their Behavior During Training
Reference: Front Psychol. 2020 Sep 24;11:582209. doi: 10.3389/fpsyg.2020.582209. eCollection 2020.
Authors: David Agustí, Rafael Ballester, Jordi Juan-Blay, William G Taylor, Florentino Huertas
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7541702/pdf/fpsyg-11-582209.pdf
Summary: This investigation aims to explore the relationship between the academic backgrounds of youth soccer coaches (U10 and U12 age groups) in Spain and the type of verbal behavior used during training sessions. The sample consisted of 70 coaches divided into two groups, depending on whether or not they had engaged with a university-level academic studies related to Physical Education and or Sport Sciences. A modified version of the "Coach Analysis and Intervention System" (CAIS), developed by Cushion et al. (2012), was used to collect data. A total of 32,886 verbal behaviors were noted and analyzed. Our results suggest that the coaches with university academic backgrounds frequently use more verbal behaviors and that these could be associated with positive effects on the players' learning and development processes. We suggest it is important to develop specific training programs aimed at optimizing the coaches' communicative and socio-affective skills in order to maximize their impact in youth athletes' learning process.
#5 Perceived barriers to implementation of injury prevention programs among collegiate women's soccer coaches
Reference: J Sci Med Sport. 2020 Sep 29;S1440-2440(20)30775-1. doi: 10.1016/j.jsams.2020.09.016.
Authors: Celeste Dix, David Logerstedt, Amelia Arundale, Lynn Snyder-Mackler
Summary: Knee injury prevention programs (IPPs) reduce knee and anterior cruciate ligament (ACL) injury rates in female athletes, however, implementation of IPPs is low. The purpose of this study was to identify barriers to implementation of IPPs among collegiate women's soccer coaches. A custom survey based on the RE-AIM (reach, effectiveness, adoption, implementation, maintenance) framework and existing literature was sent to 151 out of 153 women's National Collegiate Athletic Association (NCAA) soccer coaches in the NCAA's Eastern Region. Ten respondents reported that they did not use an IPP (Non-users), and nineteen respondents reported that they did use an IPP (Users). "Cost" was the most highly ranked barrier (median rank: 2) to implementing an IPP among Non-users. For the statement, "Who should be responsible for completing an IPP," Users said "Coaches" (47%) and "Other" (21%), while Non-users said "Strength and conditioning" (50%) and "Athletic trainers" (30%). Respondents who marked "Other", elaborated that it was the responsibility of coaches, athletes, and additional staff members. Cost was the primary barrier to implementation of an IPP. Since the majority of Non-users indicated that implementation of an IPP was the responsibility of a non-coaching staff member, cost may be a surrogate for the expense of hiring an additional staff member rather than the cost of performing the IPP itself. Additionally, using a team-based approach that encompasses athletes, coaches, and non-coaching staff members may support long-term implementation of IPPs.
#6 Head impacts in semiprofessional male Soccer players: a prospective video analysis over one season of competitive games
Reference: Brain Inj. 2020 Oct 18;1-6. doi: 10.1080/02699052.2020.1831067. Online ahead of print.
Authors: Hélène Cassoudesalle, Maxime Bildet, Hervé Petit, Patrick Dehail
Summary: Soccer exposes players to head injuries and involves repeated intentional head impacts through heading the ball. Our objective was to investigate the rate of both intentional headers and involuntary head impacts in semiprofessional male soccer players during one season. In this prospective cohort study, we followed 54 men (16-35 years) playing in two soccer clubs participating in the same regional French championship throughout the 2017-2018 season. All head impacts that occurred in competitive games were analyzed using video recordings. Player position, game exposure, referee's decision were also reported. Head impact incidence rate (IR) per 1000 player-hours, with the 95% confidence intervals (CIs) were calculated. Results: Headers IR was 3584.7 per 1000 player-hours (95% CI = 3431.9, 3737.5). Forwards and center-backs performed a higher number of headers. Involuntary head impacts IR was 44.1/1000 player-hours (95% CI = 27.1, 60.9). Just under half led the referee to stop playing time for a caregiver examination. Three concussions with a loss of consciousness after a head-to-head impact in a heading duel were recorded. Conclusions: Intentional headers were relatively common, contrary to involuntary head impacts that were however mainly due to heading duels. Head-to-head impact should lead to a systematic exit from the game for suspicion of concussion.
#7 The Effect of Fixture Congestion on Performance During Professional Male Soccer Match-Play: A Systematic Critical Review with Meta-Analysis
Reference: Sports Med. 2020 Oct 17. doi: 10.1007/s40279-020-01359-9. Online ahead of print.
Authors: Ross Julian, Richard Michael Page, Liam David Harper
Download link: https://link.springer.com/article/10.1007%2Fs40279-020-01359-9
Summary: Fixture congestion (defined as a minimum of two successive bouts of match-play, with an inter-match recovery period of < 96 h) is a frequent and contemporary issue in professional soccer due to increased commercialisation of the sport and a rise in the number of domestic and international cup competitions. To date, there is no published systematic review or meta-analysis on the impact of fixture congestion on performance during soccer match play. We sought to conduct a systematic review and meta-analysis of the literature related to the effects of fixture congestion on physical, technical, and tactical performance in professional soccer match-play. Adhering to PRISMA guidelines and following pre-registration with the Open Science Framework ( https://osf.io/fqbuj ), a comprehensive and systematic search of three research databases was conducted to identify articles related to soccer fixture congestion. For inclusion in the systematic review and meta-analysis, studies had to include male professional soccer players, a congestion period that contained two matches ≤ 96 h, and have outcome measures related to physical, technical or tactical performance. Exclusion criteria comprised non-male and/or youth players, data that only assessed impact of congestion on injury, used simulated protocols, or were grey literature, such as theses or dissertations. Out of sixteen articles included in the systematic review, only five were eligible for the meta-analysis, and the only variable that was measured consistently across studies was total distance covered. Fixture congestion had no impact on total distance covered [p = 0.134; pooled standardized mean difference; Hedge's G = 0.12 (- 0.04, 0.28)]. Between-study variance, heterogeneity, and inconsistency across studies were moderate [Cochrane's Q = 6.7, p = 0.150, I2 = 40.7% (CI 0.00, 93.34)]. Data from articles included in the systematic review suggest fixture congestion has equivocal effects on physical performance, with variation between studies and low quality of research design in some instances. Tactical performance may be negatively impacted by fixture congestion; however, only one article was identified that measured this element. Technical performance is unchanged during fixture congestion; however, again, research design and the sensitivity and relevance of methods and variables require improvement. Total distance covered is not impacted by fixture congestion. However, some studies observed a negative effect of fixture congestion on variables such as low- and moderate-intensity distance covered, perhaps suggesting that players employ pacing strategies to maintain high-intensity actions. There is a lack of data on changes in tactical performance during fixture congestion. With ever increasing numbers of competitive matches scheduled, more research needs to be conducted using consistent measures of performance (e.g., movement thresholds) with an integration of physical, technical and tactical aspects.
#8 Effect of Playing Position, Match Half, and Match Day on the Trunk Inclination, G-Forces, and Locomotor Efficiency Experienced by Elite Soccer Players in Match Play
Reference: Sensors (Basel). 2020 Oct 14;20(20):E5814. doi: 10.3390/s20205814.
Authors: José M Oliva-Lozano, Elisa F Maraver, Víctor Fortes, José M Muyor
Download link: https://www.mdpi.com/1424-8220/20/20/5814/htm
Summary: The rapid growth of wearable sensors has allowed the analysis of trunk kinematics during the match, which is necessary for having a better understanding of the postural demands of soccer players. However, some contextual variables may have an impact on the physical demands of the players. This study aimed to analyze the effect of three contextual variables (playing position, match half, and match day) on the sagittal trunk inclination, G-forces, and locomotor efficiency experienced by soccer players in match play. Then, wearable sensors were used to collect the trunk kinematics during 13 matches. Firstly, positional differences were found on the trunk inclination (p = 0.01) and the G-forces experienced by the players (p < 0.001). For example, the greatest and lowest trunk inclination was found for FW (~34.01°) and FB (~28.85°) while the greatest and lowest G-forces were found for WMF (1.16 G) and CD (1.12 G), respectively. However, there were no positional differences in the locomotor efficiency (p = 0.10). Secondly, the match half had a significant effect on the trunk inclination (p = 0.01) and the G-forces experienced by the players (p < 0.001) with significantly lower values observed during the second half. No differences between halves were found on the locomotor efficiency for any playing position (p = 0.41). Finally, no significant effect of match day on any variable was observed. This investigation is one of the first steps towards enhancing the understanding of trunk kinematics from elite soccer players. The positional differences found on the trunk inclination and G-forces imply that the development of position-specific training drills considering the postural demands is necessary to prepare the players not only for the physical demands but also for successful performance in the field of regard. The resistance to fatigue needs to be trained given the differences between halves.
#9 Effects of Combined Strength and Resisted Sprint Training on Physical Performance in U-19 Elite Soccer Players
Reference: J Strength Cond Res. 2020 Oct 15. doi: 10.1519/JSC.0000000000003829. Online ahead of print.
Authors: Mehdi Ben Brahim, Rim Bougatfa, Emna Makni, Pablo Prieto Gonzalez, Hussain Yasin, Raghad Tarwneh, Wassim Moalla, Mohamed Elloumi
Summary: This study assessed the effects of combined muscular strength and resisted sprint training using both sled and weight vest compared with regular soccer training on physical fitness of lower limbs in U-19 elite soccer players. Thirty-four male soccer players (age: 18.8 ± 0.8 years, height: 1.81 ± 0.05 m, body mass: 76.4 ± 4.9 kg, and body fat mass: 11.3 ± 4.2%) were randomly assigned into a resisted sprint training group (RSTG, n = 20), using both weight vest and sled, and a control group (CONTG, n = 14). Sprinting ability (5 m and 20 m), squat jump (SJ) and counter-movement jump (CMJ) tests, 1 repetition maximum of half-back squat (1RM half-back squat), and soccer ball-shooting speed were assessed before and after a 6-week training program. Within-group interactions showed significant combined muscular strength and resisted sprint training effects were observed for all the tests' measurements (effect sizes = 0.97 and 3.69 for 20-m sprint and SJ, respectively). However, significant increases of performances were observed for 5-m and 20-m sprinting time ( = 0.25, p < 0.01 and = 0.22, p < 0.01, respectively), SJ and CMJ ( = 0.78, p < 0.0001 and = 0.34, p < 0.001, respectively), 1 repetition maximum (1-RM) half-back squat ( = 0.45, p < 0.0001), and soccer ball-shooting speed ( = 0.41, p < 0.0001) in RSTG with large effect size, whereas the CONTG showed significant performances increase only for CMJ (p < 0.05), 1RM half-back squat (p < 0.01), and soccer ball-shooting speed (p < 0.05). We conclude that combined strength and both horizontal (weighted sled) and vertical (weighted vest) resisted sprint training are more effective than regular soccer training for enhancing sprinting and jumping abilities as well as ball-shooting speed in soccer.
#10 Neck and Trunk Strength Training to Mitigate Head Acceleration in Youth Soccer Players
Reference: J Strength Cond Res. 2020 Oct 15. doi: 10.1519/JSC.0000000000003822. Online ahead of print.
Authors: Carsten Müller, Karen Zentgraf
Summary: Heading in soccer involves repetitive head accelerations that may be detrimental for brain health. One way to mitigate adverse effects may be to increase head-neck stabilization and thus reduce the kinematic response after intentional headers. This study aimed to (a) assess associations between neck strength and head kinematics and (b) evaluate an exercise intervention designed to increase strength and attenuate head acceleration during intentional heading in youth soccer players. In 22 athletes, we used accelerometers to assess associations between neck strength and peak linear acceleration (PLA). We attached the accelerometers to the occiput and sternum, allowing us to differentiate between total, trunk, and head PLA. Longitudinally, we evaluated the effects of a 14-week twice-weekly resistance training in a subsample of 14 athletes compared with regular soccer training (N = 13). Results showed that female athletes had lower isolated neck strength (p ≤ 0.004), lower functional neck strength (p ≤ 0.017), and higher total PLA during purposeful headers compared with males (17.2 ± 3.5 g and 13.0 ± 2.3 g, respectively, at 9.6 m·s ball velocity during impact; p = 0.003). The intervention group showed moderate to large strength gains ( = 0.16-0.42), resulting in lower PLA (total -2.4 g, trunk -0.8 g, and head -1.5 g) during headers. We conclude that a resistance training focusing on cervical and trunk musculature is practicable in youth soccer, elicits strength gains, and helps to mitigate PLA during purposeful heading. Results should encourage youth strength and conditioning professionals to incorporate neck exercises as a risk reduction strategy into their training routine.
#11 Factors affecting peak impact force during soccer headers and implications for the mitigation of head injuries
Reference: PLoS One. 2020 Oct 16;15(10):e0240162. doi: 10.1371/journal.pone.0240162. eCollection 2020.
Authors: Joshua Auger, Justin Markel, Dimitri D Pecoski, Nicolas Leiva-Molano, Thomas M Talavage, Larry Leverenz, Francis Shen, Eric A Nauman
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7567382/pdf/pone.0240162.pdf
Summary: It has been documented that up to 22% of all soccer injuries are concussions. This is in part due to players purposely using their head to direct the ball during play. To provide a more complete understanding of head trauma in soccer athletes, this study characterized the effects of four soccer ball characteristics (size, inflation pressure, mass, velocity) on the resulting peak impact force as it relates to the potential for incurring neurophysiological changes. A total of six hundred trials were performed on size 4 and 5 soccer balls as well as a novel lightweight soccer ball. Impact force was measured with a force plate and ball velocity was determined using motion capture. These data were used, in conjunction with dimensional analysis to relate impact force to ball size, mass, velocity, and pressure. Reasonable reductions in allowable ball parameters resulted in a 19.7% decrease in peak impact force. Adjustments to ball parameters could reduce a high cumulative peak translational acceleration soccer athlete down into a previously defined safer low loading range. In addition, it was noted that water absorption by soccer balls can result in masses that substantially increase impact force and quickly surpass the NCAA weight limit for game play. Additional research is required to determine whether varying soccer ball characteristics will enable soccer players to avoid persistent neurophysiological deficits or what additional interventions may be necessary and the legal implications of these data are discussed.
#12 Sex and Sport Differences in College Lacrosse and Soccer Head Impact Biomechanics
Reference: Med Sci Sports Exerc . 2020 Nov;52(11):2349-2356. doi: 10.1249/MSS.0000000000002382.
Authors: Jason P Mihalik, Stephanie A Amalfe, Patricia R Roby, Cassie B Ford, Robert C Lynall, Kaitlin E Riegler, Elizabeth F Teel, Erin B Wasserman, Margot Putukian
Summary: Sport-related head impact biomechanics research has been male-centric and focused primarily on American football and ice hockey, which do not address popular sports in which both sexes participate. The purpose of this study was to quantify college female and male lacrosse and soccer head impact biomechanics. Head impact biomechanics were collected from college lacrosse and soccer players across two Division 1 college athletic programs (96 female athletes, 141 male athletes; age, 19.8 ± 1.3 yr; height, 174.8 ± 9.2 cm; mass, 72.4 ± 11.7 kg). We deployed helmetless head impact measurement devices (X2 Biosystems xPatch) before each event. Peak linear and rotational accelerations were log-transformed for random intercepts general linear mixed models, and subsequently categorized based on impact magnitude for additional categorical analyses. Most linear (69.4%) and rotational (72.3%) head impact accelerations sustained by our study cohort were categorized as mild. On average, male athletes sustained impacts with higher linear accelerations than females (P = 0.04), and lacrosse athletes sustained higher linear acceleration impacts than soccer athletes (P = 0.023). Soccer athletes sustained significantly higher-magnitude impacts during competitions versus practices (linear, P < 0.001, rotational, P < 0.001), whereas lacrosse athletes sustained higher-magnitude impacts during practices versus competition (linear, P < 0.001; rotational, P < 0.001). Male athletes sustained higher accelerations in competitions versus practice (linear, P = 0.004; rotational, P < 0.001), whereas female athletes sustained higher accelerations in practice versus competitions (linear, P < 0.001; rotational, P = 0.02). There were no interactions between sex and sport on impact magnitude. Male athletes and lacrosse athletes experience higher-magnitude head impacts. Given the limited literature in this area, future research should continue characterizing head impact biomechanics in women's and nonhelmeted sports as well as validate nonhelmeted head impact technologies.
#13 Will the real leaders please stand up? The emergence of shared leadership in semi-professional soccer teams
Reference: J Sci Med Sport. 2020 Sep 17;S1440-2440(20)30753-2. doi: 10.1016/j.jsams.2020.09.007.
Authors: Niels Mertens, Filip Boen, Niklas K Steffens, S Alexander Haslam, Katrien Fransen
Summary: High-quality leadership is often regarded as one of the main sources of competitive advantage. Especially within sport teams, a team's leadership structure has historically been considered to be stable across the season, with the coach and team captain as the formal, and often sole, leaders. In line with recent organizational research, the present study aims to broaden this perspective by also taking informal leaders into account and exploring how leadership structures among athletes within sport teams evolve over the course of a season. Using social network analysis, we analyzed the leadership structure of 20 semi-professional soccer teams (N=460 players, Mage=23.50 years; SD=4.55) at the start of the season and then again halfway through the season. More specifically, for each team we constructed a leadership network for four leadership roles (task, motivational, social, and external leadership) at these two time points. Findings suggest that leadership structures in sport teams can change considerably over the course of the competitive season, thereby challenging the classic view of stable, vertical leadership structures. The transition to more shared forms of leadership can be attributed to the emergence of informal leaders over time as players engage more strongly in leadership roles. Furthermore, our results suggest that as teams evolve towards shared leadership their functioning and performance benefits from these changes.
Conclusions: Based on these findings, we recommend that coaches actively implement a structure of shared leadership and seek to develop the leadership qualities of formal and informal athlete leaders.
#14 "All My Problems Go Away for 90 Minutes": How Football and Psychotherapy Improves Young Men's Mental Health
Reference: Am J Mens Health. Sep-Oct 2020;14(5):1557988320959992. doi: 10.1177/1557988320959992.
Authors: Amy McGrane , Niamh Bird, Chelsea Arten, Katriona O'Sullivan
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7576919/pdf/10.1177_1557988320959992.pdf
Summary: This qualitative research sought to establish the impact of an 8-week program combining football and one-to-one psychotherapy on young males' mental health, determining the factors that predict help-seeking behaviors in this group of men. Pre- and post-participation focus groups were used as the method of data collection. Six males (19-35 years old; M = 25.5) completed both pre-intervention and follow-up focus groups. Help-seeking behaviors were influenced by the appeal of football and the perception of the counselor being accessible. Barriers included gender norms, socialization, financial difficulties, and challenging social landscapes. Post-participation focus groups revealed that positive social and counseling relationships facilitated improved mental health. Sport was deemed an acceptable medium to deliver a mental health intervention as it increased social connections and facilitated help-seeking. Findings support previous research indicating that combining sports and psychotherapy positively impacts young males' mental health.
The aim of the current study was to investigate whether a moving advertisement positioned behind the goal area would influence the visual attention of participants performing a soccer penalty kick, and, whether this would an effect on subsequent motor performance.
This study aimed to describe the worst-case scenarios of professional soccer players by playing position in different durations and analyse WCS considering different contextual variables (match half and location)
Following studies were retrieved for this week:
#1 Regulatory Fit: Impact on Anxiety, Arousal, and Performance in College-Level Soccer Players
Reference: Int J Exerc Sci. 2020 Sep 1;13(5):1430-1447. eCollection 2020.
Authors: Brianna N Leitzelar, Lindsey C Blom, Justin Guilkey, Jocelyn Bolin, Anthony Mahon
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7523892/pdf/ijes-13-5-1430.pdf
Summary: Sport performance may be facilitated using regulatory fit, which is a match between individuals' situational strategy and their chronic self-regulatory strategy. However, researchers have not examined the impact of regulatory fit on psychological and physiological components of sport performance, such as anxiety and arousal. Therefore, the purpose of this study was to evaluate the psychophysiological reactions to regulatory fit by examining anxiety, arousal, and sport performance. Female college-level soccer players (n = 25) were randomly assigned to the regulatory match or regulatory mismatch conditions and completed anxiety (Competitive Sport Anxiety Inventory-2R, CSAI-2R) and underwent arousal (heart rate variability, HRV; pre-ejection period, PEP) measures pre- and post-regulatory focus manipulation. Subsequently, participants completed a sport performance task (10 penalty kicks). The impact of regulatory fit on the dependent variables was explored through repeated measures ANOVAs. Results revealed a significant time effect for cognitive anxiety and self-confidence subscales of the CSAI-2R, suggesting the penalty kicking task increased cognitive anxiety and reduced self-confidence in all participants. In addition, there was a significant interaction effect of condition on pre-ejection period (PEP), with a greater increase in PEP for those experiencing regulatory fit compared to those who were not. There were non-significant interaction and main effects for all other variables. Since PEP is an inverse measure of sympathetic (SNS) modulation, experiencing regulatory fit may reduce SNS involvement in the heartbeat. Thus, the current results indicate experiencing regulatory fit may influence arousal prior to athletic competition.
#2 Video analysis of concussion mechanisms and immediate management in French men's professional football (soccer) from 2015 to 2019
Reference: Scand J Med Sci Sports. 2020 Oct 10. doi: 10.1111/sms.13852. Online ahead of print.
Authors: Hélène Cassoudesalle, Bertrand Laborde, Emmanuel Orhant, Patrick Dehail
Summary: In this study, the concussion mechanisms were analysed in male professional competition football, with the main objective to specify the frequency of head-to-head impact, and immediate management of the concussed players was described in order to check its compliance with the recommendations of football's governing bodies. Based on continuously recorded data from the French Football Federation (FFF), a retrospective database of all reported concussions during matches in the 1st and 2nd French Male leagues was generated comprising seasons 2015/16-2018/19. Injury mechanisms, playing action, immediate medical assessment and management of concussed players, foul play-referee's decision were analysed from video recordings. In total, 41 concussions were reported (incidence rate of 0.44/1000 hours of match exposure [95% CI: 0.40 to 0.49]) of which 36 were identified and analysed on video sequences. The commonest playing action leading to concussion was aerial challenge (61%) and the main mechanism was head-to-head impact (47%). Following the head impact, 28% of concussed players were not medically assessed on-pitch and 53% returned to play the same match. Head-to-head impact was not associated with systematic medical assessment, nor with foul play. In conclusion, the main cause of concussions involved head-to-head impact occurring when two players challenge for heading the ball in the air. The detection of potential concussive head impacts and the immediate management of players possibly concussed during matches remain insufficient according to the international recommendations. Some rules changes, with particular vigilance in case of head-to-head impact, should be discussed.
#3 Behind the mask: demedicalising race and mental health in professional football
Reference: Lancet Psychiatry. 2020 Oct 9;S2215-0366(20)30418-1. doi: 10.1016/S2215-0366(20)30418-1. Online ahead of print.
Authors: Michael Bennett
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7546649/pdf/main.pdf
#4 Evaluation of a Reactive Agility Assessment Device in Youth Football Players
Reference: J Strength Cond Res. 2020 Oct 9. doi: 10.1519/JSC.0000000000003867. Online ahead of print.
Authors: Jay R Hoffman
Summary: The purpose of this study was to examine the reliability and validity of the Blazepod reactive agility device on sport-specific movements in competitive youth football players. Thirty-one male athletes (16.7 ± 1.5 years; 179.4 ± 7.0 cm; 75.0 ± 21.0 kg), all members of a youth tackle football team, volunteered to participate in this study. Subjects performed 3 reactive agility drills (side shuffle reactive agility, 1-m reactive agility, and 3-m reactive agility) at least 72 hours apart. In addition, all subjects also performed 3 traditional agility exercises: proagility, T drill, and L drill. These sessions were part of the offseason conditioning program for the football team that involved sport-specific drills. All assessments occurred following a warm-up and conducted in the same order on each occasion. To assess the validity of the reactive agility drills, the head coach was asked to rank the football playing and agility ability of the players participating in the study. The intraclass correlation coefficient values indicated that all 3 reactive agility drills displayed excellent reliability (r's ranging from 0.833 to 0.884). The measurement error was smaller than the individual variability, indicating that measurement error had a very limited effect on the results. Subjective rankings for agility significantly correlated with each of the agility and reactive agility measurements. Results of this study indicate that the Blazepod reactive agility device is a reliable measure of reactive agility performance and are consistent with the coach's perception of the athlete's agility performance, thus demonstrating construct validity.
#5 Explicit and implicit activation of gender stereotypes additively impair soccer performance and learning in women
Reference: Eur J Sport Sci. 2020 Oct 13;1-21. doi: 10.1080/17461391.2020.1833087. Online ahead of print.
Authors: Priscila Lopes Cardozo, Leon Flôres Cibeira, Luiz Carlos Rigo, Suzete Chiviacowsky
Summary: Studies involving the manipulation of instructions regarding the negative characteristics of a group or comparisons with members of another group (explicit activation of stereotypes) have shown that age, weight, and gender stereotypes can be harmful to motor performance and learning. To date, however, no study has observed whether implicit stereotype threats, such as the sex of the coach or experimenter, can also influence the acquisition of motor skills. In the present study, the individual and combined impact of implicit and explicit influences of gender stereotype on women's soccer performance and learning was examined. In a 2 × 2 design, 60 women were divided into four groups according to the presence or absence of explicit (ES) and implicit (IS) stereotypes: ES/IS, ES, IS, and control. The groups with implicit activation practiced in the presence of a male experimenter. The groups with explicit activation received instructions activating the gender negative stereotype. The control group practiced without stereotype activations. The results showed that both explicit and implicit activation additively impaired soccer performance and learning, with both main effects being significant for practice and retention. The ES/IS group showed lower scores on the task relative to the other groups, while the ES and IS groups showed worse scores compared with the control group. The findings suggest that stigmatized populations may be forced to cope with more than one social identity threat while learning sport motor skills and indicate the importance of further studies testing strategies to minimize the deleterious effects of negative stereotypes.
#6 PassVizor: Toward Better Understanding of the Dynamics of Soccer Passes
References: IEEE Trans Vis Comput Graph. 2020 Oct 13;PP. doi: 10.1109/TVCG.2020.3030359.
Authors: Xiao Xie, Jiachen Wang, Hongye Liang, Dazhen Deng, Shoubin Cheng, Hui Zhang, Wei Chen, Yingcai Wu
Summary: In soccer, passing is the most frequent interaction between players and plays a significant role in creating scoring chances. Experts are interested in analyzing players' passing behavior to learn passing tactics, i.e., how players build up an attack with passing. Various approaches have been proposed to facilitate the analysis of passing tactics. However, the dynamic changes of a team's employed tactics over a match have not been comprehensively investigated. To address the problem, we closely collaborate with domain experts and characterize requirements to analyze the dynamic changes of a team's passing tactics. To characterize the passing tactic employed for each attack, we propose a topic-based approach that provides a high-level abstraction of complex passing behaviors. Based on the model, we propose a glyph-based design to reveal the multi-variate information of passing tactics within different phases of attacks, including player identity, spatial context, and formation. We further design and develop PassVizor, a visual analytics system, to support the comprehensive analysis of passing dynamics. With the system, users can detect the changing patterns of passing tactics and examine the detailed passing process for evaluating passing tactics. We invite experts to conduct analysis with PassVizor and demonstrate the usability of the system through an expert interview.
#7 Does acute soccer heading cause an increase in plasma S100B? A randomized controlled trial
Reference: PLoS One. 2020 Oct 23;15(10):e0239507. doi: 10.1371/journal.pone.0239507. eCollection 2020.
Authors: Megan E Huibregtse, Madeleine K Nowak, Joseph E Kim, Rachel M Kalbfell, Alekhya Koppineni, Keisuke Ejima, Keisuke Kawata
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7584162/pdf/pone.0239507.pdf
Summary: The purpose of this study was to test the effect of subconcussive head impacts on acute changes in plasma S100B. In this randomized controlled trial, 79 healthy adult soccer players were randomly assigned to either the heading (n = 41) or kicking-control groups (n = 38). The heading group executed 10 headers with soccer balls projected at a speed of 25 mph, whereas the kicking-control group performed 10 kicks. Plasma samples were obtained at pre-, 0h post-, 2h post- and 24h post-intervention and measured for S100B. The primary hypothesis was that there would be a significant group difference (group-by-time interaction) in plasma S100B at 2h post-intervention. Secondary hypotheses included (1) no significant group differences in plasma S100B concentrations at 0h post- and 24h post-intervention; (2) a significant within-group increase in S100B concentrations in the heading group at 2h post-intervention compared to pre-intervention; and (3) no significant within-group changes in plasma S100B in the kicking-control group. Data from 68 subjects were available for analysis (heading n = 37, kicking n = 31). There were no differences in S100B concentrations between heading and kicking groups over time, as evidenced by nonsignificant group-by-time interaction at 2h post-intervention (B = 2.20, 95%CI [-22.22, 26.63], p = 0.86) and at all the other time points (0h post: B = -11.05, 95%CI [-35.37, 13.28], p = 0.38; 24h post: B = 16.11, 95%CI [-8.29, 40.51], p = 0.20). Part of the secondary outcome, the heading group showed elevation in plasma S100B concentrations at 24h post-intervention compared to pre-heading baseline (B = 19.57, 95%CI [3.13, 36.02], p = 0.02), whereas all other within-group comparisons in both remained nonsignificant. The data suggest that 10 bouts of acute controlled soccer headings do not elevate S100B concentrations up to 24-hour post-heading. Further dose-response studies with longer follow-up time points may help determine thresholds of acute soccer heading exposure that are related to astrocyte activation.
#8 The impact of team preferences on soccer offside judgments in laypersons: a quasi-experimental study
Reference: Cogn Res Princ Implic. 2020 Oct 23;5(1):50. doi: 10.1186/s41235-020-00253-2.
Authors: Peter Wühr, Frowin Fasold, Daniel Memmert
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7584714/pdf/41235_2020_Article_253.pdf
Summary: The present study uses a quasi-experimental design to investigate the impact of team preferences on the accuracy of offside judgments. In Experiments 1 and 2, supporters of two German soccer clubs (i.e., Borussia Dortmund and FC Schalke 04) judged offsides in artificial scenes from a match between the clubs. We expected that supporters of both clubs would less frequently report the offside position of a forward from the preferred team. The results of Experiment 1 partly confirmed the predictions. Both groups reported the offside position of a yellow forward less frequently than that of a blue forward, and this effect was much larger for supporters of Borussia Dortmund than for supporters of Schalke 04. The difference between groups could be attributed to team preferences. The weaker effect of team preference in supporters of Schalke 04 was attributed to an unexpected perceptual effect that increased the accuracy of offside judgments for blue forwards in both groups. Experiments 2 and 3 showed the presumed effect of team preferences and the perceptual effect, respectively, in isolation. In summary, the results of our experiments provide evidence for (a) an effect of team preferences and (b) an effect of shirt-background contrast on offside judgments in soccer.
#9 Neural correlates of cognitive processing capacity in elite soccer players
Reference: Biol Psychol. 2020 Oct 19;107971. doi: 10.1016/j.biopsycho.2020.107971. Online ahead of print.
Authors: Chun-Hao Wang, Chih-Chun Lin, David Moreau, Cheng-Ta Yang, Wei-Kuang Liang
Summary: Although great progress has been made in our understanding of perceptual-cognitive expertise in team sports, the neurocognitive mechanisms underlying such cognitive advantage in the face of multiple, sometimes conflicting, channels of information are not well understood. Two electroencephalographic indices associated with perceptual decisions, the P3 component of event-related potential and alpha inter-trial phase coherence (ITPC), were measured and compared across elite soccer players and non-athletic controls while performing a redundant-target task. Specifically, we adopted an effective diagnostic tool, Systems Factorial Technology, to assess participants' workload capacity. Soccer players exhibited larger workload capacity while making faster decisions compared with controls. Moreover, this larger workload capacity was associated with modulations of P3 and alpha ITPC when processing two targets relative to one target and one distractor, an effect that was not observed in controls. Together, the present findings offer a possible mechanistic explanation of perceptual-cognitive expertise in the context of team sports.
#10 Technical determinants of success in professional women's soccer: A wider range of variables reveals new insights
Reference: PLoS One. 2020 Oct 22;15(10):e0240992. doi: 10.1371/journal.pone.0240992. eCollection 2020.
Authors: Laura M S de Jong, Paul B Gastin, Maia Angelova, Lyndell Bruce, Dan B Dwyer
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7580913/pdf/pone.0240992.pdf
Summary: Knowledge of optimal technical performance is used to determine match strategy and the design of training programs. Previous studies in men's soccer have identified certain technical characteristics that are related to success. These studies however, have relative limited sample sizes or limited ranges of performance indicators, which may have limited the analytical approaches that were used. Research in women's soccer and our understanding of optimal technical performance, is even more limited (n = 3). Therefore, the aim of this study was to identify technical determinants of match outcome in the women's game and to compare analytical approaches using a large sample size (n = 1390 team performances) and range of variables (n = 450). Three different analytical approaches (i.e. combinations of technical performance variables) were used, a data-driven approach, a rational approach and an approach based on the literature in men's soccer. Match outcome was modelled using variables from each analytical approach, using generalised linear modelling and decision trees. It was found that the rational and data-driven approaches outperformed the literature-driven approach in predicting match outcome. The strongest determinants of match outcome were; scoring first, intentional assists relative to the opponent, the percentage of shots on goal saved by the goalkeeper relative to the opponent, shots on goal relative to the opponent and the percentage of duels that are successful. Moreover the rational and data-driven approach achieved higher prediction accuracies than comparable studies about men's soccer.
#11 Changes in resting-state functional brain connectivity associated with head impacts over one men's semi-professional soccer season
Reference: J Neurosci Res. 2020 Oct 21. doi: 10.1002/jnr.24742. Online ahead of print.
Authors: Hélène Cassoudesalle, Adrien Petit, Sandra Chanraud, Hervé Petit, Jérôme Badaut, Igor Sibon, Patrick Dehail
Summary: Soccer, as a contact sport, exposes players to repetitive head impacts, especially through heading the ball. The question of a long-term brain cumulative effect remains. Our objective was to determine whether exposure to head impacts over one soccer season was associated with changes in functional brain connectivity at rest, using magnetic resonance imaging (MRI). In this prospective cohort study, 10 semi-professional men soccer players, aged 18-25 years, and 20 age-matched men athletes without a concussion history and who do not practice any contact sport were recruited in Bordeaux (France). Exposure to head impacts per soccer player during competitive games over one season was measured using video analysis. Resting-state functional magnetic resonance imaging data were acquired for both groups at two times, before and after the season. With a seed-based analysis, resting-state networks that have been intimately associated with aspects of cognitive functioning were investigated. The results showed a mean head impacts of 42 (±33) per soccer player over the season, mainly intentional head-to-ball impacts and no concussion. No head impact was found among the other athletes. The number of head impacts between the two MRI acquisitions before and after the season was associated with increased connectivity within the default mode network and the cortico-cerebellar network. In conclusion, our findings suggest that the brain functioning changes over one soccer season in association with exposure to repetitive head impacts.
#12 Sleep Restriction in Elite Soccer Players: Effects on Explosive Power, Wellbeing, and Cognitive Function
Reference: Res Q Exerc Sport. 2020 Oct 21;1-8. doi: 10.1080/02701367.2020.1834071. Online ahead of print.
Authors: W Abbott, A Brett, A W Watson, H Brooker, T Clifford
Summary: The aim was to investigate the cognitive, physical, and perceptual effects of sleep restriction (SR) in soccer players following a night match. In a crossover design, nine male soccer players from the English Premier League 2 (age, 21 ± 5 years; height, 1.80 ± 0.75 m; body mass, 74.2 ± 6.8 kg) recorded their sleep quality and quantity with sleep logs and a subjective survey after two night matches (19:00); one where sleep duration was not altered (CON) and one where sleep was restricted by a later bed-time (SR). Countermovement jump height (CMJ), subjective wellbeing (1-5 likert scale for mood, stress, fatigue, sleep, and soreness), and cognitive function were measured at baseline and the morning following the match (+12 h; M + 1). Bed-time was later in SR than CON (02:36 ± 0.17 vs. 22:43 ± 29; P = .0001; ηp2 = 0.999) and sleep duration was shorter in SR than CON (5.37 ± 0.16 vs. 8.59 h ± 0.36; P = .0001; ηp2 = 0.926). CMJ decreased by ~8% after the match in both SR and CON (P = .0001; ηp2 = 0.915) but there were no differences between the conditions (P > .05; ηp2 = 0.041-0.139). Wellbeing was rated worse after both matches (P = .0001; ηp2 = 0.949) but there were no differences between the trials (P > .05; ηp2 = 0.172-257). SR did not influence cognitive function (P > .05; interaction effects, ηp2 = 0.172-257). SR following a nighttime soccer match does not impair CMJ performance, subjective wellbeing, or cognitive function the following morning.
#13 Reliability of Change-of-Direction Economy in Soccer Players
Reference: Int J Sports Physiol Perform. 2020 Oct 28;1-7. doi: 10.1123/ijspp.2019-0877. Online ahead of print.
Authors: Filippo Dolci, Andrew E Kilding, Tania Spiteri, Paola Chivers, Ben Piggott, Andrew Maiorana, Nicolas H Hart
Summary: The purpose was to evaluate the reliability of new change-of-direction-economy tests (assessing energetic efficiency when performing continuous shuttle runs) compared with common running-economy tests in soccer players Methods: Sixteen subelite, male soccer players were recruited to perform a testing battery involving running economy (RE), 10-m shuttle-running economy (SRE10), and 20-m shuttle-running economy (SRE20) at 8.4 km·h-1 mean speed on 2 different days within 48 hours. SRE10 and SRE20 consisted of continuous shuttle runs interspersed with 180° directional changes. During the RE, SRE20, and SRE10 tests, respiratory exchange ratio and oxygen uptake were collected and used to calculate the movement-economy values over any running condition as oxygen cost and energetic cost. The secondary variables (carbon dioxide production, heart rate, minute ventilation, and blood lactate) were also monitored during all tests. Depending on expression (oxygen cost or energetic cost), reliability was established for RE (CV: 5.5%-5.8%; ICC = .77-.88), SRE10 (CV: 3.5%-3.8%; ICC = .78-.96), and SRE20 (CV: 3.5%-3.8%; ICC = .66-.94). All secondary physiological variables reported good reliability (CV < 10%), except for blood lactate (CV < 35.8). The RE, SRE10, and SRE20 tests show good reliability in soccer players, whereas blood lactate has the highest variability among physiological variables during the economy tests. The assessment of change-of-direction economy through performing 20- and 10-m shuttle runs is reliable and can be applied to evaluate soccer players' energetic movement efficiency under more soccer-specific running conditions.
#14 Male and female soccer players exhibit different knee joint mechanics during pre-planned change of direction
Reference: Sports Biomech. 2020 Oct 29;1-14. doi: 10.1080/14763141.2020.1830160. Online ahead of print.
Authors: Christopher Thomas, Thomas Dos'Santos, Paul Comfort, Paul A Jones
Summary: Change of direction manoeuvres is important in soccer and associated with non-contact anterior cruciate ligament injury, yet it is not known how the mechanics differentiate between males and females during 180° turns. Twenty-eight soccer players (14 males and 14 females) performed 180° turns with ground reaction forces collected over penultimate and final contacts. A two-way (contact × limb) multivariate analysis of variance (MANOVA) were run to examine differences between contact (penultimate and final) or limb (dominant and non-dominant) for sagittal plane hip, knee and ankle peak angles and moments, and frontal plane knee abduction moments and angles between sexes. Average horizontal GRF was increased on the dominant limb, compared to non-dominant and for the final contact compared to the penultimate contact. Knee abduction angles were increased in females compared to males, while the opposite was true for knee abduction moments. Statistically significant differences were evident, with increases in peak vertical GRF, peak hip flexion angle, peak knee flexion angle, peak knee extensor moment, and peak ankle dorsiflexion angle observed in the penultimate contact compared to final contact. The results indicate the penultimate contact during turns helps reduce loading on the final contact, yet male and female soccer players exhibit different knee joint mechanics during pre-planned change of direction.
#15 Short-Term Detraining Does Not Impair Strength, Speed, and Power Performance in Elite Young Soccer Players
Reference: Sports (Basel). 2020 Oct 25;8(11):E141. doi: 10.3390/sports8110141.
Authors: Lucas A Pereira, Tomás T Freitas, Bruno Pivetti, Pedro E Alcaraz, Ian Jeffreys, Irineu Loturco
Download link: https://www.mdpi.com/2075-4663/8/11/141/htm
Summary: This study aimed to examine the effects of short-term detraining on the strength, speed, and jump capacities of under-20 soccer players. Twenty-four elite under-20 soccer players from the same professional club were assessed pre and post 26 days of detraining. The measurements were performed in the following order: countermovement jump (CMJ); 10 m linear sprint velocity; and one-repetition maximum test (1RM) in the horizontal leg-press exercise. To analyze the differences between pre- and post-tests, a paired T-test was applied. The significance level was set as p < 0.05. Soccer players exhibited a significant increase in CMJ performance (p = 0.02) and no significant differences in 10 m sprint velocity and 1RM leg-press were found after the short-term training cessation (p = 0.61; p = 0.55, respectively). We demonstrated that a short-term detraining period was capable of promoting a significant increase in the vertical jump height without inducing negative effects on the strength and speed capabilities of elite under-20 soccer players. Practitioners and sport scientists should be aware of these findings to program more effective training strategies at the beginning of the subsequent training cycle.
#16 Reproducibility and inter-observer agreement of Greulich-Pyle protocol to estimate skeletal age among female adolescent soccer players
Reference: BMC Pediatr. 2020 Oct 26;20(1):494. doi: 10.1186/s12887-020-02383-4.
Authors: Yuri V Faustino-da-Silva, Diogo V Martinho, Manuel J Coelho-E-Silva, João Valente-Dos-Santos, Jorge Conde, Tomás G Oliveira, Enio R V Ronque, Ricardo R Agostinete, Rômulo A Fernandes, Lauren B Sherar
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7586680/pdf/12887_2020_Article_2383.pdf
Summary: Skeletal age (SA) is considered the best method of assessing biological maturation. The aim of this study was to determine intra-observer (reproducibility) and inter-observer agreement of SA values obtained via the Greulich-Pyle (GP) method. In addition, the variation in calculated SAs by alternative GP protocols was examined. The sample was composed of 100 Portuguese female soccer players aged 12.0-16.7 years. SAs were determined using the GP method by two observers (OB1: experience < 100 exams using GP; OB2: experience > 2000 exams using several methods). The radiographs were examined using alternative GP protocols: (wholeGP) the plate was matched to the atlas as an overall approach; (30-boneGP) bone-by-bone inspections of 30-bones; (GPpmb) bone-by-bone inspections of the pre-mature bones only. For the 30-boneGP and GPpmb approaches, SA was calculated via the mean (M) and the median (Md). Reproducibility ranged 82-100% and 88-100% for OB1 and OB2, respectively. Inter-observer agreement (100 participants multiplied by 30 bones) was 92.1%. For specific bones, agreement rates less than 90% were found for scaphoid (81%), medial phalange V (83%), trapezium (84%) and metacarpal V (87%). Differences in wholeGP SAs obtained by the two observers were moderate (d-cohen was 0.79). Mean differences between observers when using bone-by bone SAs were trivial (30-boneGP: d-cohen less than 0.05; GPpmb: d-cohen less than 0.10). The impact of using the mean or the median was negligible, particularly when analyses did not include bones scored as mature. The GP appeared to be a reasonably reproducible method to assess SA and inter-observer agreement was acceptable. There is evidence to support a recommendation of only scoring pre-mature bones during later adolescence. Further research is required to examine whether these findings are consistent in younger girls and in boys.
The aim of this study was to provide reference data of variation in external training loads for weekly periods within annual season.
The objective of this study was to determine whether there is a decrease in the physical performance of the players in the most demanding passages (MDP) during periods of competition congestion.
Following studies were retrieved for this week:
#1 Capturing and Quantifying Tactical Behaviors in Small-Sided and Conditioned Games in Soccer: A Systematic Review
Reference: Res Q Exerc Sport. 2020 Oct 8;1-15. doi: 10.1080/02701367.2020.1823307. Online ahead of print.
Authors: Nuno Coito , Keith Davids, Hugo Folgado , Teresa Bento, Bruno Travassos
Summary: The aim was to systematically describe and analyze the tracking systems, the variables, and the statistical methods used to evaluate the players and teams' tactical behavior in small-sided and conditioned games (SSCGs). A search was done in Web of Science, PubMed, Science Direct, and Scielo databases to identify manuscripts published between 2008 and 2019 that manipulated small-sided and conditioned games (SSCGs) and analyzed tactical behaviors of players and teams. rom 349 articles identified, 31 were selected for review. To collect positional data, the global positioning system (GPS), the local position measurement (LPM) system, and TACTO were identified as reliable tracking systems. Twenty-one positional variables were identified to evaluate tactical behaviors, grouped into five main categories: team balance, playing space, width and length of playing space, and interpersonal distance. Tactical behavior patterns were analyzed using approximate entropy, sample entropy, Shannon entropy, and patterns of coordination between players and teams were analyzed using relative phase and running correlation. The tracking systems analyzed were reliable but revealed different advantages and disadvantages of their use. Authors should define the use of each tracking system based on their purpose and level of precision required for analysis. A great duplication was observed on the variables used with similar purposes of tactical analysis. The identification of the variables according to their purpose of analysis will allow a better understanding of their use in the future.
#2 Quantifying the Peak Physical Match-Play Demands of Professional Soccer Substitutes Following Pitch-Entry: Assessing Contextual Influences
Reference: Res Q Exerc Sport. 2020 Oct 8;1-12.
Authors: Samuel P Hills, Stephen Barrett, Bradley Thoseby , Liam P Kilduff , Martin J Barwood, Jon N Radcliffe, Carlton B Cooke, Mark Russell
Summary: The purpose was to quantify the peak post-pitch-entry physical responses of soccer substitutes while assessing contextual influences. Peak responses may be important performance indicators for substitutes introduced to provide a physical impact. Thirty-three professional substitutes wore Microelectromechanical Systems during 44 matches (4 ± 3 observations·player-1). Post-pitch-entry relative peak values for total and high-speed (> 5.5 m·s-1) distances, average acceleration, and PlayerLoad™ were calculated using rolling averages over 60-s to 600-s. Linear mixed models assessed contextual influences (position, substitution timing, scoreline, and location). Substitutes introduced during the final ~15 min of match-play covered less high-speed distance than first-half substitutes (~2.8-3.1 m·min-1) over 480-s to 600-s epochs, and less than 60:00-74:59 min substitutes (~1.7-1.8 m·min-1) during 540-s and 600-s epochs. Average acceleration during all except 180-s epochs was lower for 75:00+ min substitutes compared with first-half replacements (~0.27-0.43 m·s-2), and lower than 60:00-74:59 min substitutes during 60-s (~0.13 m·s-2). Substitutes introduced when their team was winning recorded greater distances over 120-s to 600-s (~6.2-7.7 m·min-1), and higher PlayerLoad™ values during 120-s, 180-s, 300-s, and 480-s epochs (~2.7-3.6 arbitrary units·min-1), compared with when scores were level at pitch-entry. Irrespective of substitution timing, substitute midfielders exceeded the total distance of substitute attackers (~5.9-16.2 m·min-1) for all except 360-s and 600-s epochs, and defenders (~13.3-26.7 m·min-1) during epochs < 300-s. This study provides benchmark data for practitioners tailoring training and recovery protocols, particularly "top-up" conditioning, to the competitive demands of soccer substitutes. Knowing how contextual factors influence substitutes' peak match-play responses may help managers/coaches assess the efficacy of substitution strategies.
#3 Varying Demands and Quality of Play Between In-Conference and Out-of-Conference Games in Division I Collegiate Women's Soccer
Reference: J Strength Cond Res. 2020 Oct 5. doi: 10.1519/JSC.0000000000003841. Online ahead of print.
Authors: Brittany N Bozzini, Bridget A McFadden, Alan J Walker , Shawn M Arent
Summary: The purpose of this study was to assess differences in physical workloads, physiological responses, and performance variables between in-conference (IC) and out-of-conference (OC) games during a collegiate women's soccer season. Female field players (N = 11), who played a minimum of 45 minutes for >50% of games, were evaluated using an integrative GPS and HR monitoring system to determine training load (TL), exercise energy expenditure (EEE), total distance covered (DIS), sprints, time spent in HR zones 4 and 5 (HRZ4 = 80-89% HRmax; HRZ5 = 90-100% HRmax), and distance covered in speed zones 4 and 5 (DISZ4 = 15.0-19.9 km·h; DISZ5 = ≥20 km·h). In addition, percent passing accuracy (PA%), dribbling success (DS%), tackling success (TS%), and challenges won (CW%) were generated for all games. Workload data were analyzed as a rate per minute playing time (PT) per game to account for differences in game duration and PT between OC (n = 7) and IC games (n = 11). Repeated-measures multivariate analyses of variance with univariate follow-ups and effect sizes (Hedges' g) were conducted to compare conditions (OC vs. CON) (p < 0.05). There were significantly greater TL, DIS, EEE, and HRZ5 per minute PT in OC versus IC games (Hedges' g: TL = 0.48; DIS = 0.20, EEE = 0.55; HRZ5 = 0.83; p < 0.05). Further analysis found significant differences in first half play favoring OC games (p < 0.05), but not second half play (p > 0.05). Based on these findings, OC games seem to be more demanding compared to IC, particularly during first half play. Emphasis should be placed on tailoring TL to the accumulating in-season demands through athlete-monitoring technology to prevent declines in performance in the latter half of the season.
#4 Effects of Moderate-to-Heavy Sled Training Using Different Magnitudes of Velocity Loss in Professional Soccer Players
Reference: J Strength Cond Res. 2020 Oct 1. doi: 10.1519/JSC.0000000000003813. Online ahead of print.
Authors: Rafael Grazioli, Irineu Loturco, Pedro Lopez, Igor Setuain, Jean Goulart, Filipe Veeck, Martinho Inácio, Mikel Izquierdo, Ronei S Pinto, Eduardo L Cadore
Summary: This study investigated the effects of a 11-week moderate-to-heavy sled training intervention with different magnitudes of velocity loss on sprint and jump performance, mechanical muscle function, and body composition in professional soccer players. Seventeen players (age 25.8 ± 4.3 years; height 180.0 ± 8.6 cm; weight 77.7 ± 9.7 kg) were randomly allocated into 2 groups, based on different magnitudes of velocity loss: 10% of velocity decrease (G10, n = 8) and 20% of velocity decrease (G20, n = 9). The velocity-based sled training consisted of 20-m resisted sprints with a progressive loading increase from 45 to 65% of body-mass throughout the intervention. Pre-intervention and postintervention sprint and jump performance, hamstring and quadriceps peak torque and isometric rate of torque development, and lower-limb lean mass measured by dual X-ray absorptiometry were assessed and compared. Two-way repeated measures analysis of variance revealed a significant time-effect for decreases in 10- and 20-m sprint times (p = 0.018 and p = 0.033, respectively), but without a time-group interaction. The G10 showed greater beneficial effects than G20 for both 10-m (-5.5 ± 3.3%, magnitude-based inference [MBI]: possibly vs. -1.7 ± 5.9%, MBI: possibly trivial) and 20-m (-2.5 ± 2.1%, MBI: possibly vs. -1.4 ± 3.7%, MBI: likely trivial) sprint times. Moreover, there was a significant time effect for countermovement jump height and quadriceps isometric peak torque, which decreased significantly after training (p = 0.019 and p = 0.010, respectively), with no within-group effect of time vs. group interaction for these respective outcomes. The novel velocity-based sled model proposed here, especially under lower magnitudes of velocity loss, was able to significantly improve linear sprint performance in professional soccer players.
#5 Performance on sprint, agility and jump tests have moderate to strong correlations in youth football players but performance tests are weakly correlated to neuromuscular control tests
Reference: Knee Surg Sports Traumatol Arthrosc. 2020 Oct 8. doi: 10.1007/s00167-020-06302-z.
Authors: Sofi Sonesson, Hanna Lindblom, Martin Hägglund
Download link: https://link.springer.com/article/10.1007%2Fs00167-020-06302-z
Summary: This study aimed at evaluating the correlation between seven different performance tests and two neuromuscular control tests in youth football players and to evaluate the influence of sex and age groups on test results. One-hundred and fifteen football players (66 boys, 49 girls) mean age 14 ± 0.7 (range 13-16) years from youth teams were tested at the start of the second half of the competitive season. A test battery including agility t-test, 505 agility test, single-leg hop for distance test, side-hop test, countermovement jump test, 10-m sprint test, 20-m sprint test, tuck jump assessment (TJA) and drop vertical jump (DVJ) was completed. Correlations between the seven different performance tests of agility, jump and sprint ability were generally moderate to strong (r = 0.534-0.971). DVJ did not correlate with the performance tests (rho = 0.004 to - 0.101) or with TJA total score (rho = 0.127). There were weak to moderate correlations between TJA total score and the performance tests (r = - 0.323-0.523). Boys performed better than girls in all performance tests (p < 0.001) and in TJA total score (p = 0.002). In boys, older players performed better than younger players in the majority of the tests, while there was no clear age influence among girls. Sprint performance was moderately to strongly correlated with agility and jump performance, and performance tests were weakly to moderately correlated to TJA, while DVJ did not correlate with the other tests. Boys performed better than girls on performance tests and TJA. An age effect on performance was evident in boys but not in girls.
#6 Football - Novel Approaches to Tackle Diabetes
Reference: Exp Clin Endocrinol Diabetes. 2020 Oct 7. doi: 10.1055/a-1262-6352. Online ahead of print.
Authors: Karsten Müssig, Henning E Adamek
Summary: Balanced diet and regular physical activity are of key importance to the prevention of the development and progression of non-communicable diseases. In 2050, 50% of the European population is expected to be obese. Cardiovascular diseases, diabetes mellitus, cancer, as well as joint impairments, will further increase. Therefore, programmes are critical to the improvement of the population's health status in the long run. New ways have to be found that allow addressing more people than with the current approaches. Football has a great potential to attract people at risk for or with already existing non-communicable diseases, such as type 2 diabetes, to participate in health-promoting programmes. The novel football version, walking football was developed for elderly players, aiming at avoiding injuries and physical overload. The present article gives a brief overview on the metabolic effects of recreational football, particularly walking football, as well as health-promoting programmes offered by professional football clubs in humans at risk for or with already existing non-communicable diseases.
#7 Flywheel squats versus free weight high load squats for improving high velocity movements in football. A randomized controlled trial
Reference: BMC Sports Sci Med Rehabil. 2020 Oct 2;12:61. doi: 10.1186/s13102-020-00210-y. eCollection 2020.
Authors: Edvard H Sagelv, Sigurd Pedersen, Lars Petter R Nilsen, Andrea Casolo, Boye Welde, Morten B Randers, Svein Arne Pettersen
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7532637/pdf/13102_2020_Article_210.pdf
Summary: High load (HL: > 85% of one repetition maximum (1RM)) squats with maximal intended velocity contractions (MIVC) combined with football sessions can be considered a relevant and time-efficient practice for maintaining and improving high velocity movements in football. Flywheel (FW) resistance exercise (RE) have recently emerged with promising results on physical parameters associated with football performance. In this randomized controlled trial over 6 weeks, 38 recreationally active male football players randomly performed RE with MIVCs two times per week as either 1) FW squats (n = 13) or 2) barbell free weight (BFW) HL squats (n = 13), where a third group served as controls (n = 12). All three groups conducted 2-3 football sessions and one friendly match a week during the intervention period. Pre- to post changes in 10-m sprint, countermovement jump (CMJ) and 1RM partial squat were assessed with univariate analyses of variance. The FW and BFW group equally improved their 10-m sprint time (2 and 2%, respectively, within group: both p < 0.001) and jump height (9 and 8%, respectively, within group: both p < 0.001), which was superior to the control group's change (between groups: both p < 0.001). The BFW group experienced a larger increase (46%) in maximal squat strength than the FW group (17%, between groups: p < 0.001), which both were higher than the control group's change (both p < 0.001). Squats carried out with FWs or BFWs where both are performed with MIVCs and combined with football sessions, were equally effective in improving sprint time and jump height in football players. The BFW group experienced a more than two-fold larger increase in maximal partial squat strength than the FW group in maximal partial squat strength. This presents FW RE as an alternative to BFW HL RE for improving high velocity movements in football.
#8 Mass Gathering Emergency Medicine Organization for the Union of European Football Associations' Under-21 Championship 2019 in Bologna, Italy
Reference: Disaster Med Public Health Prep. 2020 Oct 7;1-4. doi: 10.1017/dmp.2020.291. Online ahead of print.
Authors: Guglielmo Imbriaco, Alfonso Flauto, Tiziano Bussolari, Fiorella Cordenons, Giovanni Gordini
Summary: Football events represent a type of Mass Gathering Events (MGE) where crowd behavior, temperature and Heat Index, absence of free water, and alcohol consumption can lead to an increased need for medical assistance in participants. This report describes the environmental issues, organization, and healthcare assistance provided during the four matches of the Union of European Football Associations' (UEFA) Under-21 tournament held in Bologna in June, 2019. The four matches had a total of 72655 spectators; 31 patients required medical assistance with a mean Patient Presentation Rate (PPR) of 0.41; Mean Transport To Hospital Rate (TTHR) of 0.04; with PPR and TTHR comparable with literature findings. Majority of patients suffered from minor injuries and illnesses, and were treated directly in stadium medical sites. Medical assistance involved volunteer rescuers, emergency nurses, and physicians; resources were efficiently allocated and provided effective care to every patient.Climate factors, heat and humidity, the absence of free water, and increased alcohol consumption appear to be associated with increased requests for medical assistance. The retrospective analysis of a wider range of environmental factors, and the historical experience developed during similar MGEs suggest the need for a more comprehensive, improved approach for adequately assessing risk and planning the necessary healthcare resources.
#9 Does Distance Produce Beauty? The Influence of COVID-19 Lockdown on the Coach-Athlete Relationship in a Chinese Football School
Reference: Front Psychol. 2020 Sep 11;11:560638. doi: 10.3389/fpsyg.2020.560638. eCollection 2020.
Authors: Juan Li, Hongyan Gao, Pan Liu, Caixia Zhong
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7516042/pdf/fpsyg-11-560638.pdf
Summary: This paper examined the relationship between coaches and youth athletes in China by comparing data collected before and after the lockdown. A total of 221 youth athletes aged 13-19 years in one professional football school completed coach-athlete relationship questionnaires. The rank-sum test was used to verify the differences in the data. The results of the Mann-Whitney U test showed that mean value of the three dimensions of the coach-athlete relationship (closeness, commitment, and complementarity) increased after the COVID-19 lockdown. The results also showed that athletes of different age categories showed different changes in the coach-athlete relationship after the lockdown, and the changes were not significantly related to the severity of the COVID-19 epidemic. The theoretical and practical implications are discussed.
#10 The Influence of Emotion in the Management of Amateur Football Organizations
Reference: Front Psychol. 2020 Sep 4;11:2218. doi: 10.3389/fpsyg.2020.02218. eCollection 2020.
Authors: Melany Hebles , Vicente Javier Prado-Gascó, Orlando Llanos-Contreras, Mario Alguacil
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7499803/pdf/fpsyg-11-02218.pdf
Summary: This article is oriented to the analysis of organizational and emotional variables in amateur sporting organizations. The general objective is to analyze the influence of organizational variables such as service quality, transactional leadership, and transformational leadership and emotional variables such as affective commitment, emotional attachment investment, and emotional attachment dividend to predict the credibility that members of amateur sporting organizations perceive, as well as their degree of identification and loyalty. The opinions of 203 members of Chilean amateur football teams [169 men and 34 women, with ages between 18 and 68 years (mean = 32.75 years, DT = 9.92)] have been analyzed through a self-completed questionnaire. To reach the objectives, two types of differential but complementary analyses, in the form of hierarchical regression models (from hereon, HRMs) and qualitative comparative analysis (from hereon, QCA), were performed. The results obtained suggest that the organizational variables are better predictors than the emotional variables in all of the cases. In the same way, the inclusion of the emotional variables improves the predictive capacity of the proposed models to explain identification and loyalty, but not in the case of credibility. In general, the variables considered seem to explain 37% of the credibility, 56% of loyalty, and 65% of identification. On the other hand, considering the results of the QCA, no variable turned out to be necessary. However, different combinations of variables (conditions) were observed that were able to explain between 47 and 91% of the cases of the variables analyzed. In general, based on these results, it was observed that the emotional variables were important in interaction with other organizational ones since they are present in the three combinations that most explain identification and loyalty and are also present in the three combinations that most explain credibility. This study contributes to the literature by supporting the importance of managing emotions in order for sporting organizations to be more successful.
#11 Differentiation Between Tendinous, Myotendinous and Myofascial Injuries by L-BIA in Professional Football Players
Reference: Front Physiol. 2020 Sep 4;11:574124. doi: 10.3389/fphys.2020.574124. eCollection 2020.
Authors: Lexa Nescolarde, Joaquim Terricabras, Sandra Mechó, Gil Rodas, Javier Yanguas
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7500181/pdf/fphys-11-574124.pdf
Summary: The aim was to differentiate by localized bioimpedance (L-BIA) measurements 24 h after injury, between tendinous, myotendinous junction (MTJ), and myofascial junction (MFJ) injuries, previously diagnosed by MRI exam. To evaluate by L-BIA, the severity of MTJ injuries graded from 1 to 3, and to determine the relationship between days to return to play (RTP) and L-BIA measurements. 3T MRI and tetra polar L-BIA was used to analyzed 37 muscle injuries 24 h after injury in 32 male professional football players, (23.5 ± 1.5 kg m-2; 1.8 ± 0.1 m; 20-30 year.) between the 2016-2017 and 2017-2018 seasons. Muscle injuries were classified by The British Athletics Muscle Injury Classification (BAMIC). Percentage difference of L-BIA parameters [resistance (R), reactance (Xc), and phase angle (PA)] of the injured side were calculated considering contralateral non-injured side as the reference value. According to BAMIC classification and by MRI exam, we found tendinous (n = 4), MTJ (n = 26), and MFJ (n = 7) muscle injuries. In addition, MTJ injuries were grouped according to the severity of injury in grade 1 (n = 11), grade 2 (n = 8), and grade 3 (n = 7). Significant decrease (P < 0.01) was found in the L-BIA parameters R, Xc, and PA, in both MTJ and MFJ as well as in the different grades of MTJ injuries. In particular, in Xc (P < 0.001), which is related to muscle cell disruption. Regarding days to RTP, there was statistical significance among the three different grades of MTJ injuries (P < 0.001), especially when grade 1 was compared to grade 3 and grade 2 compared to 3. L-BIA is a complementary method to imaging diagnostic techniques, such as MRI and US, to quantify MTJ and MFJ injuries. In addition, the increase in the severity of the MTJ injury resulted in higher changes of the Xc parameter and longer time to RTP.
#12 Short and long lever adductor squeeze strength values in 100 elite youth soccer players: Does age and previous groin pain matter?
Reference: Phys Ther Sport. 2020 Oct 6;46:243-248. doi: 10.1016/j.ptsp.2020.10.001. Online ahead of print.
Authors: Matthew D DeLang, J Craig Garrison, Joseph P Hannon, Ryan P McGovern, John Christoforetti, Kristian Thorborg
Summary: The purpose was to examine adductor squeeze strength in elite youth soccer players by investigating the relationship of age and previous one-year groin pain on adductor squeeze force outputs, and to provide reference values for youth players. Elite youth soccer players (n = 100; age 14.5 ± 1.9 years; height 168.0 ± 10.7 cm; mass 60.7 ± 13.0 kg) participated. Adductor squeeze tests were captured in short and long lever positions, and groin pain assessed via subjective retrospective questionnaire. Multiple linear regressions were computed to compare the effects of age and previous one-year groin pain on adductor squeeze strength. Raw adductor squeeze force values (N) had a moderate positive relationship with age (short r = 0.517, p < 0.001; long r = 0.457, p < 0.001), but not when force is normalized to body mass (N/kg; short r = 0.014, p = 0.444; long r = -0.173, p = 0.043). Previous groin pain did not have an effect on short or long lever squeeze strength. Reference values for long lever adductor squeeze strength (3.59 ± 0.77 Nm/kg) are provided. Age and previous groin pain do not have an effect on adductor squeeze strength values in elite youth soccer players, so comparing values to the present adolescent cohort can be quickly interpreted without adjustment for age or previous injury.
#13 The role of alcohol in the link between national football (soccer) tournaments and domestic abuse - Evidence from England
Reference: Soc Sci Med. 2020 Oct 22;268:113457. doi: 10.1016/j.socscimed.2020.113457. Online ahead of print.
Authors: Anna Trendl, Neil Stewart, Timothy L Mullett
Summary: Domestic abuse is increasingly recognised as a serious public health concern worldwide. Previous research has suggested a link between national football (soccer) tournaments and domestic abuse. While hypothesized to be a significant factor, the role alcohol plays in this relationship has not yet been explored quantitatively. In this study, using 10 years' worth of crime data (from 2010 to 2019) from the second largest police force in England (West Midlands Police), we explored the effect of England draws, losses, and wins in national football tournaments on the number of alcohol and non-alcohol-related domestic abuse cases reported to the police. Results from a series of negative binomial regression analyses show that the number of reported alcohol-related domestic abuse cases increases by 47%, 95% confidence interval [26%-71%], following an England football victory. This effect is limited to alcohol-related cases. The estimate translates into a 0.53, 95% CI [0.3-0.8], increase in the daily rate of alcohol-related cases per 100,000 individuals. The England win effect survives various robustness checks (including the re-analysis of a dataset from another geographical area in England), and its time course is strongly consistent with a causal link between England's football victories and an increase in alcohol-related domestic abuse. We also found a comparable increase in the number of other (not classified as domestic abuse) alcohol-related violent crimes on England win days. Further research is required to understand the exact causal pathway between national football tournaments, alcohol consumption, and violent behaviours in domestic settings.
#14 A New Strategy to Integrate Heath-Carter Somatotype Assessment with Bioelectrical Impedance Analysis in Elite Soccer Player
Reference: Sports (Basel). 2020 Oct 27;8(11):E142. doi: 10.3390/sports8110142.
Authors: Francesco Campa, Tindaro Bongiovanni, Catarina N Matias, Federico Genovesi, Athos Trecroci, Alessio Rossi, F Marcello Iaia, Giampietro Alberti, Giulio Pasta, Stefania Toselli
Download link: https://www.mdpi.com/2075-4663/8/11/142/htm
Summary: Easy-to-apply and quick methods for evaluate body composition are often preferred when assessing soccer teams. This study aimed to develop new equations for the somatotype quantification that would reduce the anthropometric measurements required by the Heath and Carter method, integrating the somatotype assessment to the bioelectrical impedance analysis (BIA). One hundred and seventy-six male elite soccer players (age 26.9 ± 4.5 years), registered in the Italian first division (Serie A), underwent anthropometric measurements and BIA. Endomorphy, mesomorphy, and ectomorphy were obtained according to the Heath and Carter method, while fat mass (FM) and fat free mass (FFM) estimated using a BIA-derived equation specific for athletes. The participants were randomly split into development (n = 117) and validation groups (n = 59, 1/3 of sample). The developed models including resistance2/stature, FM%, FFM, contracted arm and calf circumference, triceps, and supraspinal skinfolds had high predictive ability for endomorphy (R2 = 0.83, Standard Error of Estimate (SEE) = 0.16) mesomorphy (R2 = 0.80, SEE = 0.36), and ectomorphy (endomorphy (R2 = 0.87, SEE = 0.22). Cross validation revealed R2 of 0.80, 0.84, 0.87 for endomorphy, mesomorphy, and ectomorphy, respectively. The proposed strategy allows the integration of somatotype assessment to BIA in soccer players, reducing the number of instruments and measurements required by the Heath and Carter approach.
#15 Effects of Unloaded vs. Ankle-Loaded Plyometric Training on the Physical Fitness of U-17 Male Soccer Players
Reference: Int J Environ Res Public Health. 2020 Oct 27;17(21):E7877. doi: 10.3390/ijerph17217877.
Authors: Mehrez Hammami, Nawel Gaamouri, Katsuhiko Suzuki, Ridha Aouadi, Roy J Shephard, Mohamed Souhaiel Chelly
Download link: https://www.mdpi.com/1660-4601/17/21/7877/htm
Summary: The aim of this study was to compare the impact of two differing plyometric training programs (loaded plyometrics (with 2.5% of body mass placed above the ankle joint) vs. unloaded plyometrics), performed biweekly for 10 weeks, on the physical fitness of elite junior male soccer players. Participants aged 16.0 ± 0.5 years were randomly assigned between unloaded plyometrics (UP; n = 12), loaded plyometrics (LP; n = 14) and control (C; n = 12) groups. Two-way analyses of performance (group x time) were assessed by 40-m sprint times; 9-3-6-3-9 m sprints with 180° turns (S180°); 9-3-6-3-9 m sprints with backward and forward running (SBF); and 4 × 5 m sprints (S4 × 5 m); four jump tests; measures of static and dynamic balance; repeated change of direction tests and the Yo-Yo intermittent recovery test. Both LP and UP enhanced sprinting performance relative to C (p < 0.05) but performance increased more in LP relative to UP (p < 0.05) in all sprints except 40 m. Change of direction times were also significantly shortened by LP relative to UP (p < 0.05) and C (p < 0.01) in all tests, with no significant differences between UP and C. Jumps heights increased similarly in both LP and UP relative to C (p < 0.05), with no significance between LP and UP. LP and UP also enhanced repeated change of direction scores relative to C (p < 0.01) with greater changes in LP than in UP (p < 0.01). Finally, LP enhanced some balance scores relative to UP (p < 0.05) and C (p < 0.05). We conclude that the introduction of 10 weeks of in-season loaded plyometrics into the regimen of U17 male soccer players yields gains in several physical performance scores relative to either unloaded plyometrics or the control training regimen.
The study aimed at comparing the effects of two training approaches on prepubescent soccer players' sprint performance.
The aim was to investigate if making the skill aquisition phase more difficult or easier would enhance performance in soccer juggling and if this practice has a positive intertask transfer effect to ball reception performance.
Following studies were retrieved for this week:
#1 Concussion in soccer: a comprehensive review of the literature
Reference: Concussion. 2020 Jul 1;5(3):CNC76. doi: 10.2217/cnc-2020-0004.
Authors: James Mooney, Mitchell Self, Karim ReFaey, Galal Elsayed, Gustavo Chagoya, Joshua D Bernstock, James M Johnston
Summary: Sports-related concussion has been examined extensively in collision sports such as football and hockey. However, historically, lower-risk contact sports such as soccer have only more recently garnered increased attention. Here, we review articles examining the epidemiology, injury mechanisms, sex differences, as well as the neurochemical, neurostructural and neurocognitive changes associated with soccer-related concussion. From 436 titles and abstracts, 121 full texts were reviewed with a total of 64 articles identified for inclusion. Concussion rates are higher during competitions and in female athletes with purposeful heading rarely resulting in concussion. Given a lack of high-level studies examining sports-related concussion in soccer, clinicians and scientists must focus research efforts on large-scale data gathering and development of improved technologies to better detect and understand concussion.
#2 The Effects of Long-Term Magnesium Creatine Chelate Supplementation on Repeated Sprint Ability (RAST) in Elite Soccer Players
Reference: Nutrients. 2020 Sep 28;12(10):E2961. doi: 10.3390/nu12102961.
Authors: Adam Zajac, Artur Golas, Jakub Chycki, Mateusz Halz, Małgorzata Magdalena Michalczyk
Download link: https://www.mdpi.com/2072-6643/12/10/2961/pdf
Summary: The aim of the study was to evaluate the effects of 16 weeks of a low dose of magnesium creatine chelate supplementation on repeated sprint ability test (RAST) results in elite soccer players. Twenty well-trained soccer players participated in the study. The players were divided randomly into two groups: the supplemented group (SG = 10) and placebo group (PG = 10). Out of the 20 subjects selected for the study, 16 (SG = 8, PG = 8) completed the entire experiment. The SG ingested a single dose of 5500 mg of magnesium creatine chelate (MgCr-C), in 4 capsules per day, which was 0.07 g/kg/d. The PG received an identical 4 capsules containing corn starch. Before and after the study, the RAST was performed. In the RAST, total time (TT), first and sixth 35 m sprint length (s), average power (AP) and max power (MP) were measured. Additionally, before and after the test, lactate LA (mmol/L) and acid-base equilibrium pH (-log(H+)), bicarbonates HCO3- (mmol/L) were evaluated. Also, in serum at rest, creatinine (mg/dL) concentration was measured. After the study, significantly better results in TT, AP and MP were observed in the SG. No significant changes in the RAST results were observed in the PG. After the study, significant changes in the first 35 m sprint, as well as the sixth 35 m sprint results were registered in the SG, while insignificant changes occurred in the PG. A significantly higher creatinine concentration was observed. Also, a higher post-RAST concentration of LA, HCO3- and lower values of pH were observed in April, May and June compared with baseline values. The long timeframe, i.e., 16 weeks, of the low dose of magnesium creatine chelate supplementation improved the RAST results in the SG. Despite the long period of MgCr-C supplementation, in the end of the study, the creatinine level in the SG reached higher but still reference values.
#3 Is It High Time to Increase Elite Soccer Substitutions Permanently?
Reference: Int J Environ Res Public Health. 2020 Sep 25;17(19):E7008. doi: 10.3390/ijerph17197008.
Authors: Gustavo R Mota, Izabela Aparecida Dos Santos, Rhaí André Arriel, Moacir Marocolo
Download link: https://www.mdpi.com/1660-4601/17/19/7008/pdf
Summary: Rules determine how team sport matches occur. Match-induced fatigue is specific to each sport, and may be associated with injury incidence. For example, the injury rate in soccer is distinctly higher during matches than in training sessions. Understanding the differences between team sports rules might be useful for enhancing rules (e.g., safer sport). Therefore, this study aimed to evaluate the impact of the rule-induced physical demands between soccer, futsal, basketball, and handball, focusing on substitution rules. Data from the elite team sports' rules (e.g., absolute and relative court dimensions; the number of players, substitutions allowed, total game time, time-outs) were collected, including the changes due to the coronavirus disease (COVID-19) pandemic in soccer substitutions, and comparisons were performed. The data showed that soccer has higher rule-induced physical demands: e.g., substantially lower substitution rate, higher dimensions in absolute (eight to fifteen times), and relative (four to eight times) values. Simulations also showed that soccer has extremely large differences, even considering COVID-19 substitution changes (from three to up to five). We conclude that elite soccer has remarkably higher overall rule-induced physical demands than elite futsal, basketball and handball, and increasing soccer substitutions permanently (e.g., unlimited) might mitigate overall soccer demands.
#4 Diagnostic performance of the Strength and Pain Assessment (SPA) score for non-contact muscle injury screening in male soccer players
Reference: Phys Sportsmed. 2020 Sep 29;1-7. doi: 10.1080/00913847.2020.1824986. Online ahead of print.
Authors: Luca Semperboni, Chiara Vignati, Maria Giulia Ballatore, Anita Tabacco, Chiara Busso, Marco A Minetto
Summary: The aims of this study were to develop a clinical-feature based scoring system for muscle injury screening and to assess its diagnostic accuracy when large number of injuries are suspected. A prospective diagnostic accuracy study was performed according to the Standards for Reporting of Diagnostic Accuracy (STARD) criteria. The diagnostic accuracy of the Strength and Pain Assessment (SPA) score (index test) was assessed in relation to muscle ultrasonography (reference standard). A large (n = 175) number of male soccer players met the inclusion/exclusion criteria: clinical assessment (i.e., evaluation of pain onset modality, location, distribution, impact on performance, and manual muscle strength testing) and ultrasonography were performed in all players after 48 hours from the sudden or progressive onset of muscle pain during or after a soccer competition. 91 of 175 cases (52%) were classified as functional muscle disorders, while signs of muscle tear were observed in the remaining 84 of 175 (48%) cases that were classified as structural muscle injuries. The median (1st - 3rd quartile) value of the SPA score was significantly (P < 0.001) lower in the functional disorder group [9 (9-10)] compared to the structural injury group [12 (12-13)]. The area under the Receiver Operating Characteristic curve for different cutoff points of the SPA score was 0.977 (95% confidence intervals: 0.957-0.998) and the optimal cutoff value of the SPA score providing the greatest sensitivity and specificity (respectively, 99% and 89%) was 11. This study found that the SPA score has high diagnostic accuracy for structural muscle injuries and could be used as a valid screening tool in soccer players presenting with sudden or progressive onset of muscle pain during or after a competition.
#5 Effects of Field Position on Fluid Balance and Electrolyte Losses in Collegiate Women's Soccer Players
Reference: Medicina (Kaunas). 2020 Sep 24;56(10):E502. doi: 10.3390/medicina56100502.
Authors: Haoyan Wang, Kate S Early, Bailey M Theall, Adam C Lowe, Nathan P Lemoine Jr, Jack Marucci, Shelly Mullenix, Neil M Johannsen
Download link: https://www.mdpi.com/1010-660X/56/10/502/pdf
Summary: Research investigating hydration strategies specialized for women's soccer players is limited, despite the growth in the sport. The purpose of this study was to determine the effects of fluid balance and electrolyte losses in collegiate women's soccer players. Eighteen NCAA Division I women's soccer players were recruited (age: 19.2 ± 1.0 yr; weight: 68.5 ± 9.0 kg, and height: 168.4 ± 6.7 cm; mean ± SD), including: 3 forwards (FW), 7 mid-fielders (MD), 5 defenders (DF), and 3 goalkeepers (GK). Players practiced outdoor during spring off-season training camp for a total 14 practices (WBGT: 18.3 ± 3.1 °C). The main outcome measures included body mass change (BMC), sweat rate, urine and sweat electrolyte concentrations, and fluid intake. Results were analyzed for comparison between low (LOW; 16.2 ± 2.6° C, n = 7) and moderate risk environments for hyperthermia (MOD; 20.5 ± 1.5 °C, n = 7) as well as by field position. The majority (54%) of players were in a hypohydrated state prior to practice. Overall, 26.7% of players had a %BMC greater than 0%, 71.4% of players had a %BMC less than -2%, and 1.9% of players had a %BMC greater than -2% (all MD position). Mean %BMC and sweat rate in all environmental conditions were -0.4 ± 0.4 kg (-0.5 ± 0.6% body mass) and 1.03 ± 0.21 mg·cm-2·min-1, respectively. In the MOD environment, players exhibited a greater sweat rate (1.07 ± 0.22 mg·cm-2·min-1) compared to LOW (0.99 ± 0.22 mg·cm-2·min-1; p = 0.02). By position, DF had a greater total fluid intake and a lower %BMC compared to FW, MD, and GK (all p < 0.001). FW had a greater sweat sodium (Na+) (51.4 ± 9.8 mmol·L-1), whereas GK had the lowest sweat sodium (Na+) (30.9 ± 3.9 mmol·L-1). Hydration strategies should target pre-practice to ensure players are adequately hydrated. Environments deemed to be of moderate risk of hyperthermia significantly elevated the sweat rate but did not influence fluid intake and hydration status compared to low-risk environments. Given the differences in fluid balance and sweat responses, recommendations should be issued relative to soccer position.
#6 Use of Numerically Blinded Ratings of Perceived Exertion in Soccer: Assessing Concurrent and Construct Validity
Reference: Int J Sports Physiol Perform. 2020 Sep 28;1-7. doi: 10.1123/ijspp.2019-0740. Online ahead of print.
Authors: Ric Lovell, Sam Halley, Jason Siegler, Tony Wignell, Aaron J Coutts, Tim Massard
Summary: The purpose was to examine the concurrent and construct validity of numerically blinded ratings of perceived exertion (RPEs). A total of 30 elite male youth soccer players (age 16.7 [0.5] y) were monitored during training and matches over a 17-wk in-season period. The players' external loads were determined via raw 10-Hz global positioning system. Heart rate (HR) was collected continuously and expressed as Bannister and Edwards training impulses, and minutes >80% of the players predetermined the maximum HR by the Yo-Yo Intermittent Recovery Test Level 1. RPE was collected confidentially 10 to 15 min after training/matches using 2 methods: (1) a traditional verbal response to the 0 to 100 category-ratio "centiMax" scale (RPE) and (2) numerically blinded RPE centiMax scale (RPEblind) with the response selected manually via a 5 × 7-in tablet "slider." The RPE and RPEblind were divided by 10 and multiplied by the duration to derive the sessional RPE. Linear mixed models compared ratings, and within-subject repeated-measures correlations assessed the sessional RPE versus HR and external load associations. There were no differences between the RPE and RPEblind (0.19; 95% confidence intervals, -0.59 to 0.20 au, P = .326) or their session values (13.5; 95% confidence intervals, -17.0 to 44.0 au, P = .386), and the ratings were nearly perfectly correlated (r = .96). The associations between the sessional RPE versus HR and external load metrics were large to very large (r = .65-.81), with no differences between the RPE methods (P ≥ .50). The RPEblind also reduced verbal anchor clustering and integer bias by 11% and 50%, respectively. RPEblind demonstrated concurrent and construct validity versus the traditional method, and may be used in situations where practitioners have concerns regarding the authenticity of athlete ratings.
#7 Profiling the Post-match Top-up Conditioning Practices of Professional Soccer Substitutes: An Analysis of Contextual Influences
Reference: J Strength Cond Res. 2020 Oct;34(10):2805-2814. doi: 10.1519/JSC.0000000000003721.
Authors: Samuel P Hills, Stephen Barrett, Matt Busby, Liam P Kilduff, Martin J Barwood, Jon N Radcliffe, Carlton B Cooke, Mark Russell
Summary: Soccer practitioners implement "top-up" conditioning sessions to compensate for substitutes' limited match-play exposure. Although perceived to be valuable for reducing injury risk and augmenting positive physical adaptations, little research has considered the demands of post-match top-up training. To quantify post-match top-up responses, 31 professional soccer players wore 10 Hz microelectromechanical systems after 37 matches whereby they were selected in the match-day squad as substitutes (184 observations; 6 ± 5 observations·player). Linear mixed models and effect sizes (ES) assessed the influence of contextual factors on 23 physical performance variables. Top-ups lasted 17.13 ± 7.44 minutes, eliciting total and high-speed distances of 1.7 ± 6.2 km and 0.4 ± 1.7 km, respectively. Each contextual factor (i.e., position, substitution timing, match location, result, time of day, stage of the season, and fixture density) influenced at least 4 of the dependent variables profiled (p ≤ 0.05). Top-up duration; total, moderate-speed, and low-speed distance; and the number of repeated high-intensity efforts were greater for unused vs. used substitutes (ES: 0.38-0.73, small to moderate). Relative to away matches, home top-ups elicited heightened total, low-speed, and high-speed distances, alongside more moderate-speed accelerations and decelerations, and repeated high-intensity efforts (ES: 0.25-0.89, small to moderate). Although absolute and relative running distances were generally the highest when the fixture density was low, the greatest acceleration and deceleration demands were observed during the most congested fixture periods. Late-season top-ups typically elicited lower absolute physical responses than early and mid-season sessions. These data provide important information for practitioners when considering the aims and design of substitute top-up conditioning sessions, particularly with reference to contextual influences.
#8 Effects of Maturation on Physical Fitness Adaptations to Plyometric Drop Jump Training in Male Youth Soccer Players
Reference: J Strength Cond Res. 2020 Oct;34(10):2760-2768. doi: 10.1519/JSC.0000000000003151.
Authors: Tiago Vera-Assaoka, Rodrigo Ramirez-Campillo, Cristian Alvarez, Felipe Garcia-Pinillos, Jason Moran, Paulo Gentil, David Behm
Summary: Effects of maturation on physical fitness adaptations to plyometric drop jump training in male youth soccer players. J Strength Cond Res 34(10): 2760-2768, 2020-The objective of this study was to compare the effects of maturation on physical fitness adaptations to a twice weekly, 7-week plyometric drop jump training program. Seventy-six young male soccer players (aged 10-16 years) participated in this randomized controlled trial. Before and after the intervention, a physical fitness test battery was applied (countermovement jump; drop jump from 20 to 40 cm; 5 multiple bounds test; 20-m sprint time; change of direction speed; 2.4-km running time-trial; 5 repetition maximum [RM] squat; and maximal kicking distance). Participants were randomly divided into an active soccer-control group (CG) with Tanner stage maturation of 1-3 (CG-early; n = 16) or Tanner stage 4-5 (CG-late; n = 22), and to plyometric drop jump training groups with Tanner stage 1-3 (plyometric jump training [PJT]-early; n = 16) or 4-5 (PJT-late; n = 22). The analysis of variance and effect size (ES) measures revealed that when compared with their age-matched controls, the PJT-early (ES = 0.39-1.58) and PJT-late (ES = 0.21-0.65) groups showed greater improvements (p < 0.05) in sprint time, 2.4-km running time-trial, change of direction speed, 5RM squat, jumping, and kicking distance. The PJT-early exceeded the PJT-late group with greater (p < 0.05) improvements in drop jump from 20 cm (ES = 1.58 vs. 0.51) and 40 cm (ES = 0.71 vs. 0.4) and kicking distance (ES = 0.95 vs. 0.65). Therefore, a 7-week plyometric drop jump training program was effective in improving physical fitness traits in both younger and older male youth soccer players, with greater jumping and kicking adaptations in the less-mature athletes.
#9 Does an Optimal Relationship Between Injury Risk and Workload Represented by the "Sweet Spot" Really Exist? An Example From Elite French Soccer Players and Pentathletes
Reference: Front Physiol. 2020 Aug 28;11:1034. doi: 10.3389/fphys.2020.01034. eCollection 2020.
Authors: Adrien Sedeaud, Quentin De Larochelambert, Issa Moussa, Didier Brasse , Jean-Maxence Berrou, Stephanie Duncombe, Juliana Antero, Emmanuel Orhant, Christopher Carling, Jean-Francois Toussaint
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7485291/pdf/fphys-11-01034.pdf
Summary: The aim was to examine the relationships between the occurrence and severity of injuries using three workload ratios (ACWR, EWMA, REDI) in elite female soccer players and international male and female pentathletes. Female soccer players in the U16 to U18 national French teams (n = 24) and international athletes (n = 12, 4 women and 8 men) in the French modern pentathlon team were monitored throughout an entire season. The Acute Chronic Workload Ratio (ACWR), the Exponentially Weighted Moving Averages (EWMA), and the Robust Exponential Decreasing Index (REDI) were calculated for internal load by the ROE method in soccer and external load in pentathlon. The occurrence and severity of injuries (determined according to time-loss) were quantified in the sweet spot zone [0.8; 1.3] and compared to the other zones of load variation: [0; 0.8], [1.3; 1.5], [1.5; +8], using the three ratios. Over the study period, a total of sixty-six injuries (2.75 per athlete) were reported in the soccer players and twelve in pentathletes (1 per athlete). The cumulative severity of all injuries was 788 days lost in soccer and 36 in pentathlon: respectively, 11.9 days lost per injury in soccer player and 3.0 per pentathlete. The mean values across the three methods in soccer showed a higher number of injuries detected in the [0; 0.8] workload ratio zone: 22.3 ± 6.4. They were 17.3 ± 3.5 in the sweet spot ([0.8-1.3] zone) and 17.6 ± 5.5 in the [1.5; +8] zone. In comparison to the [1.5; +8] zone, soccer players reported a higher number of days lost to injuries in the presumed sweet spot and in the [0-0.8] zone: 204.7 ± 28.7 and 275.0 ± 120.7 days, respectively. In pentathletes, ten of the twelve injuries (83.3%) occurred in the presumed sweet spot. REDI was the only method capable of tracking workloads over all-time series. In the present cohort of elite soccer players and pentathletes, acute chronic workload calculations showed an association with injury occurrence and severity but did not provide evidence supporting existence of a sweet spot diminishing injury risk.
#10 Factors Associated with Ball Velocity and Low Back Pain During Kicking in Adolescent Soccer Players
Reference: Open Access J Sports Med. 2020 Sep 7;11:133-143. doi: 10.2147/OAJSM.S262990. eCollection 2020.
Authors: Michio Tojima, Seira Takei , Suguru Torii
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7490067/pdf/oajsm-11-133.pdf
Summary: The factors associated with low back pain (LBP) and the relationship between LBP and ball velocity during kicking motion of adolescent soccer players remain largely unknown. This study aims to clarify the relationship between increasing ball velocity and LBP in adolescent soccer players. Adolescent soccer players were divided into two groups according to the presence and absence of LBP (LBP group, n=38 and NBP (no back pain) group, n=29, respectively). Real-time kick motion was measured using a three-dimensional motion analysis system and the angle of the lumbar spine, hip, and center of mass (COM) were calculated. Regression analysis was used to identify factors associated with ball velocity and LBP. In addition, Pearson's correlation coefficients were determined between the angle of the lumbar spine and hip, and ball velocity and position of COM in the extracted phase from regression analysis. The major factor associated with increasing ball velocity was the rotation angle of both hips (Adjusted R2=0.244) and vertical position of COM during kicking (Adjusted R2=0.262). Furthermore, the factors associated with LBP were the flexion angle of kick-side hip (OR=1.126) and abduction angle of both hips (kick-side OR=1.124; support-side OR=0.872). The factors for ball velocity and LBP were related to the maximum hip extension phase. In the hip extension phase of kicking, compared with the NBP group, the LBP group showed lesser extension and external rotation of the kick-side hip angle. In the hip flexion phase of kicking, the ball velocity was correlated with vertical (r=0.56)/anterior (r=0.46) position of COM in the NBP group. To compensate for this restricted hip motion, the LBP group could extend and rotate their lumbar spine, which may likely cause stress to this region.
#11 Impact of football matches on number of visits to an emergency department
Reference: Emergencias. 2020 Sep;32(5):345-348.
Authors: Sendoa Ballesteros Peña, Irrintzi Fernández Aedo, Gorka Vallejo de la Hoz
Summary: The purpose was to analyze the impact of a local football team's matches on patient demand for hospital emergency department care in Bilbao, in the Spanish province of Biscay. We retrieved the number of patients coming to the emergency department on the days and hours of matches played by Bilbao's Athletic Club during the 2017-2019 and 2018-2019 seasons and compared the caseloads with those on the same days of the weeks before and after the matches (control days). Ninety-five match days were studied. Nineteen of the matches were considered key events. Visits by adults to the emergency department fell by a statistically significant 7.5% (95% CI, 4.6%-11.6%) when matches were being played in Bilbao. The decrease was 8.4% (95% CI, 5.3%-12.6%) when matches were played away. The decrease in pediatric emergencies was 32.7% (95% CI, 7.4%-68.3%) in the hours while important matches were played outside the city. The impact of football on the number of visits to our hospital emergency department was modest, except during important away matches.
#12 Kinematic Analysis of the Postural Demands in Professional Soccer Match Play Using Inertial Measurement Units
Reference: Sensors (Basel). 2020 Oct 22;20(21):E5971. doi: 10.3390/s20215971.
Authors: José M Oliva-Lozano, Elisa F Maraver, Víctor Fortes, José M Muyor
Download link: https://www.mdpi.com/1424-8220/20/21/5971/htm
Summary: The development of wearable sensors has allowed the analysis of trunk kinematics in match play, which is necessary for a better understanding of the postural demands of the players. The aims of this study were to analyze the postural demands of professional soccer players by playing position. A longitudinal study for 13 consecutive microcycles, which included one match per microcycle, was conducted. Wearable sensors with inertial measurement units were used to collect the percentage (%) of playing time spent and G-forces experienced in different trunk inclinations and the inclination required for different speeds thresholds. The inclination zone had a significant effect on the time percentage spent on each zone (p < 0.001, partial eta-squared (ηp2 = 0.85) and the G-forces experienced by the players (p < 0.001, ηp2 = 0.24). Additionally, a significant effect of the speed variable on the trunk inclination zones was found, since trunk flexion increased with greater speeds (p < 0.001; ηp2 = 0.73), except for midfielders. The players spent most of the time in trunk flexion between 20° and 40°; the greatest G-forces were observed in trunk extension zones between 0° and 30°, and a linear relationship between trunk inclination and speed was found. This study presents a new approach for the analysis of players' performance. Given the large volumes of trunk flexion and the interaction of playing position, coaches are recommended to incorporate position-specific training drills aimed to properly prepare the players for the perception-action demands (i.e., visual exploration and decision-making) of the match, as well as trunk strength exercises and other compensatory strategies before and after the match.
#13 Long-term influence of technical, physical performance indicators and situational variables on match outcome in male professional Chinese soccer
Reference: J Sports Sci. 2020 Oct 27;1-11. doi: 10.1080/02640414.2020.1836793. Online ahead of print.
Authors: Changjing Zhou, Alberto Lorenzo Calvo, Sam Robertson, Miguel-Ángel Gómez
Summary: This study aimed to determine whether the role of technical, physical performance indicators and situational variables in determining match outcome has varied from a long-term analysis (seasons 2012 to 2017) of the Chinese Soccer Super League (CSL). The sample included 1,429 matches where 17 technical performance-related indicators, 11 physical performance-related indicators and two situational variables (match location and quality of opposition) were analysed. Three binary logistic regression models (inclusion of different variables) were used to measure the level of association between factors and match outcome over the six seasons studied. Results of models 1 and 2 revealed that shots on target, possession, total distance in ball possession, total distance out of ball possession, and match location exerted a decreased influence on winning the matches from 2012 to 2014 seasons. However, these indicators play a more important role in winning matches from 2014 to 2017 seasons. Additionally, the quality of opposition has a continuously increased negative effect on the match outcome. In model 3, more variables, such as high-speed distance, high-speed out of ball possession, had a meaningful influence on winning the match. These results provide valuable information about performance indicators and situational variables on winning the matches from a long-term approach.
#14 Electromyographic Comparison of Flywheel Inertial Leg Curl and Nordic Hamstring Exercise Among Soccer Players
Reference: Int J Sports Physiol Perform. 2020 Oct 28;1-6. doi: 10.1123/ijspp.2019-0921. Online ahead of print.
Authors: Helene Pedersen, Atle Hole Saeterbakken, Markus Vagle, Marius Steiro Fimland, Vidar Andersen
Summary: The Nordic hamstring exercise (NHE) has been shown to considerably reduce hamstring injuries among soccer players. However, as the load in the NHE is the person's own bodyweight, it is a very heavy exercise and difficult to individualize. The flywheel inertial leg curl (FLC) could be an alternative since the eccentric overload is based on the amount of work produced in the concentric movement. Therefore, the primary aim of this study was to compare the activation in the hamstrings at long muscle lengths in the NHE and the FLC in amateur soccer players. Fifteen male amateur soccer players performed 5 repetitions in each exercise in a randomized and counterbalanced order. The concentric and eccentric movements were divided into lower and upper phases. Surface EMG was measured distally, proximally, and in the middle, at both muscles. In the lower phase in the eccentric movement, there were no significant differences between the 2 exercises (P = .101-.826). In the lower concentric movement, the FLC led to higher activation in all parts of both the biceps femoris (31%-52%, P < .001) and the semitendinosus (20%-35%, P = .001-.023). Both exercises activated the hamstrings similarly at long muscle lengths during eccentric contractions (Nordic hamstring, nonsignificantly higher). However, when performing concentric contractions, the FLC induced higher activations. Therefore, the FLC could be a useful alternative to the NHE and particularly suitable for weaker athletes before progressing to NHE.
The aims of this investigation were to report team average and positional changes to match play physical performance across an European Championsleague season while statistically controlling for situational and contextual variables.
This study aimed to analyse the effect of different starting stance widths and knee flexion angles on movement time, center of mass trajectory and velocity in goalkeepers' diving saves.
Following studies were retrieved for this week:
#1 Monitoring Cardiorespiratory Fitness in Professional Soccer Players: Is It Worth the Prick?
Reference: Int J Sports Physiol Perform. 2020 Oct 1;1-5. doi: 10.1123/ijspp.2019-0911. Online ahead of print.
Authors: Martin Buchheit, Ben M Simpson, Mathieu Lacome
Summary: The aim was to compare between-tests changes in submaximal exercise heart rate (HRex, 3 min, 12 km/h) and the speed associated with 4 mmol/L of blood lactate (V4mmol) in soccer players to get insight into their level of agreement and respective sensitivity to changes in players' fitness. A total of 19 elite professional players (23  y) performed 2 to 3 graded incremental treadmill tests (3-min stages interspersed with 1 min of passive recovery, starting speed 8 km/h, increment 2 km/h until exhaustion or 18 km/h if exhaustion was not reached before) over 1.5 seasons. The correlation between the changes in HRex and V4mmol was examined. Individual changes in the 2 variables were compared (>2 × typical error considered "clear"). The changes in HRex and V4mmol were largely correlated (r = .82; 90% confidence interval, .65-.91). In more than 90% of the cases, when a clear individual change in HRex was observed, it was associated with a similar clear change in V4mmol (the same direction, improvement, or impairment of fitness) and conversely. When it comes to testing players submaximally, the present results suggest that practitioners can use HRex or V4mmol interchangeably with confidence. However, in comparison with a field-based standardized warm-up run (3-4 min, all players together), the value of a multistage incremental test with repeated blood lactate samplings is questionable for a monitoring purpose given its time, labor, cost, and poorer player buy-in.
#2 Birth sex ratio in the offspring of professional male soccer players: influence of exercise training load
Reference: Hum Reprod. 2020 Oct 2;deaa225. doi: 10.1093/humrep/deaa225. Online ahead of print.
Authors: D Vaamonde, A C Hackney, J M Garcia Manso, E Arriaza Ardiles, M Vaquero
Summary: This is the first study assessing the influence of exercise training load on the offspring sex ratio of children from male professional athletes, observing a bias toward more females being born as a result of both high-intensity and high-volume loads, with intensity having the greatest effect. There is a relatively constant population sex ratio of males to females among various species; however, certain events and circumstances may alter this population sex ratio favoring one sex over the other. Seventy-five male professional soccer players from First Division soccer teams. Offspring variables were sex of the offspring, number of children and order of birth. Exercise training variables were volume and intensity. Total offspring was 122 children (52 males (42.6%), 70 females (57.4%)). Analysis revealed that increase in either the volume (P < 0.001) or intensity (P < 0.001) of training by the players shifted the birth offspring ratio more toward females. Within the sample of females born, more births (i.e. number) were observed as a consequence of training at the highest intensity (45 out of 70; P < 0.001), no such pattern occurred within males (P > 0.05). When female versus male births were compared within each intensity, only the high-intensity comparison was significant (45 (75%) females vs 15 (25%) males, P < 0.001). While this is the first study assessing differences in the sex ratio of the offspring of male athletes (i.e. soccer players), we acknowledge there are limitations and confounders within our approach; e.g. small sample size, ethnic background and variations in the timing of intercourse relative to ovulation as well as in sex hormone levels. As such, we propose that future research is needed to confirm or refute our findings. It is recommended that such work expand on the measurements obtained and conduct direct assessment of sperm characteristics. The findings of the study support the fact that different stressors on the body may alter the sex of the offspring. While in the present study the stressor is the excessive training load of soccer players, other events may lead to similar results. The bias in offspring sex ratio may have important implications for demography and population dynamics, as well as genetic trait inheritance.
#3 Myositis Ossificans of the Adductor Longus in a Soccer Player
Reference: J Orthop Sports Phys Ther. 2020 Oct;50(10):586. doi: 10.2519/jospt.2020.9573.
Authors: Michael Zarro, Kathleen Tamberrino, E McKenzie Bane
Summary: A 20-year-old male collegiate soccer goalkeeper presented to an athletic trainer during the season complaining of right (dominant kicking leg) groin pain. The athletic trainer identified a mass and hematoma and suspected myositis ossificans. The patient was referred to the team physician, who ordered radiographs and magnetic resonance imaging to confirm the diagnosis and rule out other injuries. Imaging demonstrated an adductor longus muscle strain with myositis ossificans.
#4 Prevalence of concomitant knee injuries associated with anterior cruciate ligament tear in kabaddi and football players
Reference: J Clin Orthop Trauma. 2020 Oct;11(Suppl 5):S784-S788. doi: 10.1016/j.jcot.2020.05.037. Epub 2020 Jun 6.
Authors: Ravi Gupta, Anil Kapoor, Gladson DavidMasih
Summary: There is little literature available about the type of sports and concomitant knee injury. The aim was to help in better prediction of concomitant knee injuries in football and kabaddi players. Five hundred and seventeen male athletes [Football (n = 226) and Kabaddi players (n = 291)] aged between 16 and 35 years were enrolled in the study. These were categorized into five groups depending upon the time interval between injury and surgery (0-3 months, 3-6 months, 6-9 months, 9-12 months, 12-18 months and 18-24 months). Meniscal and chondral damage present at the time of ACL reconstruction was documented. The overall incidence of meniscal tear was more in kabaddi players (220/291) as compared to football players (144/226; p = 0.003). The incidence of both menisci tear was more in kabaddi as compared to football (p = 0.02). Incidence of lateral meniscus tear (147/291) in kabaddi was more as compared to football (84/226; p = 0.002). The incidence of condylar damage was comparable in both groups. Medial femoral condyle was more commonly injured in both the sports irrespective of time frame. The chances of meniscus injuries were more in kabaddi players compared to football players in ACL deficient knee. The time interval between injury and surgery had a direct correlation with meniscus and chondral injuries.
#5 Accuracy of maturity prediction equations in individual elite male football players
Reference: Ann Hum Biol. 2020 Jun;47(4):409-416. doi: 10.1080/03014460.2020.1783360.
Authors: Jan Willem Ajw Teunissen, Nikki Rommers, Johan Pion, Sean P Cumming, Roland Rössler, Eva D'Hondt, Matthieu Lenoir, Geert J P Savelsbergh, Robert M Malina
Download link: https://www.tandfonline.com/doi/abs/10.1080/03014460.2020.1783360?needAccess=true#aHR0cHM6Ly93d3cudGFuZGZvbmxpbmUuY29tL2RvaS9wZGYvMTAuMTA4MC8wMzAxNDQ2MC4yMDIwLjE3ODMzNjA/bmVlZEFjY2Vzcz10cnVlQEBAMA==
Summary: Equations predicting age at peak height velocity (APHV) are often used to assess somatic maturity and to adjust training load accordingly. However, information on the intra-individual accuracy of APHV in youth athletes is not available. The purpose of this study is to assess the accuracy of predication equations for the estimation of APHV in individual youth male football players. Body dimensions were measured at least every three months in 17 elite youth male football players (11.9 ± 0.8 years at baseline) from the 2008-2009 through the 2011-2012 seasons. APHV was predicted at each observation with four suggested equations. Predicted APHV was compared to the player's observed APHV using one-sample-t-tests and equivalence-tests. Longitudinal stability was assessed by comparing the linear coefficient of the deviation to zero. Predicted APHV was equivalent to the observed APHV in none of the players. A difference with a large effect size (Cohen's d > 0.8) was noted in 87% of the predictions. Moreover, predictions were not stable over time in 71% of the cases. None of the evaluated prediction equations is accurate for estimating APHV in individual players nor are predictions stable over time, which limits their utility for adjusting training programmes.
#6 The Influence of Recruitment Age and Anthropometric and Physical Characteristics on the Development Pathway of English Academy Football Players
Reference: Int J Sports Physiol Perform. 2020 Sep 29;1-9. doi: 10.1123/ijspp.2019-0534. Online ahead of print.
Authors: Mark R Noon, Emma L J Eyre, Matthew Ellis, Tony D Myers, Rhys O Morris, Peter D Mundy, Ryan Penny, Neil D Clarke
Summary: The purpose was to investigate the influence of recruitment age on retention and release across the development pathway and to explore the influence of anthropometric and physical characteristics on retention and release at different ages throughout the development pathway and the likelihood of obtaining a professional contract. Following receipt of ethics approval, a cross-sectional study tracking 4 cohorts of players over 5 years assessed 76 male youth football players (11-16 y) from an English football academy on 3 occasions annually in anthropometry, countermovement jump height, and linear (30 and 15 m) and multidirectional sprint time. Players were categorized based on their start and release date. Starting early (ie, before U12) in an academy was a key indicator of obtaining a professional contract, representing 87% of the players signed. Bayesian regression models suggest that the majority of differences in physical characteristics between players that were released and retained are trivial, small, and/or uncertain. Players who attained a professional contract at 18 had slower 15- and 30-m sprint times at U13 to U15 (P > 0 = .87-.99), slower multidirectional sprint times at U14 (P > 0 = .99), and lower countermovement jump height at U13 to U16 (P > 0 = .88-.99) compared with players who did not gain a contract. Players recruited early have an increased likelihood of gaining a professional contract. Physical assessments lack utility when used in isolation as a talent-identification tool.
#7 Football spectatorship and selected acute cardiovascular events: lack of a population-scale association in Poland
Reference: Kardiol Pol. 2020 Sep 21. doi: 10.33963/KP.15606. Online ahead of print.
Authors: Jenny E Simon, Łukasz A Małek, Andrzej Śliwczyński, Witold Śmigielski, Karol Korczak, Wojciech Drygas
Download link: https://www.mp.pl/kardiologiapolska/en/node/15606/pdf
Summary: The status of football spectatorship-induced emotional stress as a risk factor for acute cardiovascular (CV) events remains in dispute. Aims: To examine the relation between football spectatorship and the incidence of selected acute CV events across the Polish male population. Events occurring in male patients aged 35 and older across Poland during three tournaments (the 2012 and 2016 European Championships - EC and the 2018 World Cup - WC) were retrospectively analysed through hospital admission codes obtained from the National Health Fund. Of interest were the following primary diagnoses: acute myocardial infarction (AMI, I21), sudden cardiac arrest (SCA, I46), sudden arrhythmias (SA, I47 - I49). The same dates in the years before and after the tournaments constituted the reference periods. A total of 255,383 patients were included in this study. There were no significant differences in the incidence of events between the combined exposure and reference periods: RR = 1.05 (95% CI 0.97 to 1.14, P = 0.20) for AMI, RR = 1.08 (95% CI 0.87 to 1.35, P = 0.47) for SCA, and RR = 1.02 (95% CI 0.98 to 1.06, P = 0.32) for SA. Individual tournament analyses revealed a higher incidence of AMI (RR = 1.20, 95% CI 1.12 - 1.30, P < 0.001) during WC. However, day-by-day analysis of WC did not find a higher incidence of AMI on match vs. match-free days. The emotional stress evoked by football spectatorship is insufficiently potent to precipitate a population-scale increase in selected acute CV events.
#8 Comparing football bettors' response to social media marketing differing in bet complexity and account type - An experimental study
Reference: J Behav Addict. 2020 Sep 26. doi: 10.1556/2006.2020.00056. Online ahead of print.
Authors: Scott Houghton, Mark Moss
Download link: https://akjournals.com/downloadpdf/journals/2006/aop/article-10.1556-2006.2020.00056/article-10.1556-2006.2020.00056.xml
Summary: The current study aimed to assess how sports bettors respond to advertised bets on social media and whether this differs dependent upon bet complexity and social media account type. Employing a 3 × 2 repeated measures design, 145 regular football bettors were recruited to take part in an online study requiring them to rate bets advertised upon social media, providing indications of their likelihood to bet, confidence in the bet and how much they would stake on the bet. Advertised bets differed in terms of complexity (low, medium and high) and each bet was presented separately on both an operator account and an affiliate account. Data analysis highlighted a significant interaction between bet complexity and account type, with bettors rating themselves as being more likely to bet and more confident in bets which were presented on an affiliate account for medium complexity bets but not for low or high complexity bets. This study provides initial evidence that affiliate marketing of sports betting increases bettor's confidence in certain types of bets. This heightens previously addressed concerns around affiliate marketing, given that affiliates are financially incentivised to attract custom toward gambling operators. Future research should explore risk factors for increased uptake of affiliate marketing, and the impact on gambling behaviour.
#9 Inertial flywheel knee- and hip-dominant hamstring strength exercises in professional soccer players: Muscle use and velocity-based (mechanical) eccentric overload
Reference: PLoS One. 2020 Oct 2;15(10):e0239977. doi: 10.1371/journal.pone.0239977. eCollection 2020.
Authors: Luis Suarez-Arrones, F Javier Núñez, Pilar Lara-Lopez, Valter Di Salvo, Alberto Méndez-Villanueva
Download link: https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0239977&type=printable
Summary: The primary aim of the present study was to analyze mechanical responses during inertial knee- and hip-dominant hamstring strengthening exercises (flywheel leg-curl and hip-extension in conic-pulley), and the secondary aim was to measure and compare regional muscle use using functional magnetic resonance imaging. Mean power, peak power, mean velocity, peak velocity and time in the concentric (CON) and eccentric (ECC) phases were measured. The transverse relaxation time (T2) shift from pre- to post-exercise were calculated for the biceps femoris long (BFl) and short (BFs) heads, semitendinosus (ST) and semimembranosus (SM) muscles at proximal, middle and distal areas of the muscle length. Peak and mean power in flywheel leg-curl were higher during the CON than the ECC phase (p<0.01). ECC peak power was higher than CON phase (p<0.01) in conic-pulley hip-extension exercise, while mean power was higher during the CON than ECC phase (p<0.01). Flywheel leg-curl showed a higher T2 values in ST and BFs and BFl (p<0.05), while the conic-pulley hip-extension had a higher T2 values in the proximal region of the ST and BFl (p<0.05). In conclusion, ECC overload was only observed in peak power during the conic-pulley hip-extension exercise. Flywheel leg-curl involved a greater overall use of the 4 muscle bellies, more specifically in the ST and BFs, with a selective augmented activity (compared with the conic-pulley) in the 3 regions of the BFs, while conic-pulley hip-extension exercise selectively targeted the proximal and medial regions of the BFl. Physiotherapists and strength and conditioning coaches should consider this when optimizing the training and recovery process for hamstring muscles, especially after injury.
#10 Post-competition recovery strategies in elite male soccer players. Effects on performance: A systematic review and meta-analysis
Reference: PLoS One. 2020 Oct 2;15(10):e0240135. doi: 10.1371/journal.pone.0240135. eCollection 2020.
Authors: Albert Altarriba-Bartes, Javier Peña, Jordi Vicens-Bordas, Raimon Milà-Villaroel, Julio Calleja-González
Download link: https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0240135&type=printable
Summary: The main aim of the present review was to update the available evidence on the value interest of post-competition recovery strategies in male professional or semi-professional soccer players to determine its effect on post-game performance outcomes, physiological markers, and wellness indicators. A structured search was carried out following the PRISMA guidelines using six online databases: Pubmed, Scopus, SPORTDiscus, Web of Science, CINAHL and Cochrane Central Register of Controlled Trials. The risk of bias was completed following the Cochrane Collaboration Guidelines. Meta-analyses of randomized controlled trials were conducted to determine the between and within-group effects of different recovery strategies on performance, physiological markers and wellness data. Final meta-analyses were performed using the random-effects model and pooled standardized mean differences (SMD). Five randomized controlled trials that used Compression Garments (n = 3), Cold Water Immersion (n = 1), and acute Sleep Hygiene Strategy (n = 1) were included. Greater CMJ values at 48h for the intervention group (SMD = 0.70; 95% CI 0.14 to 1.25; p = 0.001; I2 = 10.4%) were found. For the 20-m sprint and MVC, the results showed no difference either at 24h or 48h. For physiological markers (CK and CRP) and wellness data (DOMS), small to large SMD were present in favor of the intervention group both at 24h (-0.12 to -1.86) and 48h (-0.21 to -0.85). No heterogeneity was present, except for MVC at 24h (I2 = 90.4%; p = 0.0012) and CALF DOMS at 48h (I2 = 93.7%; p = 0.013). The use of recovery strategies offers significant positive effects only in jumping performance (CMJ), with no effects on the 20-m sprint or MVC. Also, the use of recovery strategies offers greater positive effects on muscle damage (physiological markers and wellness data), highlighting the importance of post-match recovery strategies in soccer.
The aims were to analyse the physical response of professional soccer players during training considering the contextual factors of match location, season period and quality of opposition.
The purpose was to investigate long corner kicks within the English Premier League that entered the goal area (6-yard box) or the critical are (6-12 yards from the goal-line in the width of the goal area) with the defining outcome occurring after the first contact.
Following studies were retrieved for this week:
#1 How to Use Global Positioning Systems (GPS) Data to Monitor Training Load in the "Real World" of Elite Soccer
Reference: Front Physiol. 2020 Aug 20;11:944. doi: 10.3389/fphys.2020.00944. eCollection 2020.
Authors: Guillaume Ravé, Urs Granacher, Daniel Boullosa, Anthony C Hackney, Hassane Zouhal
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7468376/?report=reader
#2 Successful return to professional men's football (soccer) competition after the COVID-19 shutdown: a cohort study in the German Bundesliga
Reference: Br J Sports Med. 2020 Sep 24;bjsports-2020-103150. doi: 10.1136/bjsports-2020-103150. Online ahead of print.
Authors: Tim Meyer, Dietrich Mack, Katrin Donde, Oliver Harzer, Werner Krutsch, Annika Rössler, Janine Kimpel, Dorothee von Laer, Barbara C Gärtner
Download link: https://bjsm.bmj.com/content/bjsports/early/2020/09/23/bjsports-2020-103150.full.pdf
Summary: The aim was to evaluate the restart of the German Bundesliga (football (soccer)) during the COVID-19 pandemic from a medical perspective. Participants were male professional football players from the two highest German leagues and the officials working closely with them. Our report covers nine match days spread over 9 weeks (May to July 2020). Daily symptom monitoring, PCR testing for SARS-CoV-2 RNA twice weekly, and antibody tests (on two occasions-early during the phase in May 2020 and in the week of the last match) were conducted. Target variables were: (1) onset of typical COVID-19 symptoms, (2) positive PCR results, and (3) IgG seroconversion against SARS-CoV-2. All detected seroconversions were controlled by neutralisation tests. Suspicious symptoms were reported for one player; an immediate additional PCR test as well as all subsequent diagnostic and antibody tests proved negative for coronavirus. Of 1702 regularly tested individuals (1079 players, 623 officials members), 8 players and 4 officials tested positive during one of the first rounds of PCR testing prior to the onset of team training, 2 players during the third round. No further positive results occurred during the remainder of the season. 694 players and 291 officials provided two serum samples for antibody testing. Nine players converted from negative/borderline to positive (without symptoms); two players who initially tested positive tested negative at the end of the season. 22 players remained seropositive throughout the season. None of the seroconversions was confirmed in the neutralisation test. Professional football training and matches can be carried out safely during the COVID-19 pandemic. This requires strict hygiene measures including regular PCR testing.
#3 Characteristics of Soccer Players Undergoing Primary Hip Arthroscopy for Femoroacetabular Impingement: A Sex- and Competitive Level-Specific Analysis
Reference: Am J Sports Med. 2020 Sep 23;363546520958697. doi: 10.1177/0363546520958697. Online ahead of print.
Authors: Niv Marom, Matthew S Dooley, Joost A Burger, Brenda Chang, Struan H Coleman, Anil S Ranawat, Bryan T Kelly, Danyal H Nawabi
Summary: Radiographic features of femoroacetabular impingement (FAI) are prevalent in kicking athletes, especially soccer players. However, there remains a paucity of data on the characteristics of symptomatic soccer players with an established diagnosis of FAI. The purpose was to report on patient demographics, injury, and clinical and radiographic characteristics in a large cohort of soccer players who underwent primary hip arthroscopy for FAI and to perform a sex- and competition level-specific analysis of these data. An institutional hip preservation registry containing 3318 consecutive primary hip arthroscopies for FAI performed between March 2010 and January 2016 was retrospectively reviewed for patients identified as soccer players. Patient demographics, injury characteristics, and clinical and radiographic findings were recorded, and sex- and competition level-specific differences were analyzed. A total of 421 hips (336 soccer players) were identified, including 257 (61.0%) men and 164 (39.0%) women. Of these, 105 (24.9%) were reported as highly competitive, 194 (46.1%) as competitive, 75 (17.8%) as recreational, and 47 (11.2%) did not report a level. The majority of the 336 soccer players (231 hips; 55%) reported chronic hip pain lasting >6 months with no acute injury at the initial visit. Alpha angle, coronal center-edge angle, and femoral version on computed tomography scan measured 64.5°± 12°, 32.3°± 9°, and 13.7°± 10° (mean ± SD), respectively. There were 230 (55%) hips with a type 2 anterior inferior iliac spine (AIIS), 78 (18.5%) with a type 1 AIIS, and 19 (4.5%) with a type 3 AIIS. When compared with male athletes, female athletes had more hip internal rotation on physical examination (14.9° vs 8°; P < .001), lower alpha angles (57.5° vs 68.5°; P < .001), and lower-grade AIIS morphology (P = .003). Acute injury as the reason for hip symptoms was most likely in the highly competitive group (P < .001). Female soccer players were more likely to have less severe clinical and radiographic findings than were male soccer players. Acute injury as the cause of hip symptoms was more common in highly competitive players. Focusing on soccer players with an established FAI diagnosis, the findings of this study suggest that there are sex- and competition level-based differences in the presentation, physical examination, and imaging characteristics among the players. These findings can better guide clinicians in the diagnostic evaluation of symptomatic soccer players with FAI and in tailoring treatment recommendations to specific cohorts.
#4 Soccer-related head injuries-analysis of sentinel surveillance data collected by the electronic Canadian Hospitals Injury Reporting and Prevention Program
Reference: Paediatr Child Health. 2019 Aug 30;25(6):378-384. doi: 10.1093/pch/pxz116. eCollection 2020 Oct.
Authors: Sarah Zutrauen, Steven McFaull, Minh T Do
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7492621/pdf/pxz116.pdf
Summary: Participating in sports is a great way to gain physical, psychological, and social benefits. However, it also carries the risk of injury. Soccer is one of the most popular sports worldwide, and in recent years, there have been concerns about potential vulnerabilities to head injuries. The aim was to investigate soccer-related head injuries (SRHIs), using data from the electronic Canadian Hospitals Injury Reporting and Prevention Program (eCHIRPP) surveillance system. Specifically, we aim to compare characteristics of SRHI cases to all head injury cases within the eCHIRPP database. Descriptive analyses of emergency department (ED) injury surveillance data (2011 to 2017) for individuals aged 5 to 29 years from all participating eCHIRPP sites. Computation of proportionate injury ratios (PIR) comparing SRHIs to all head injuries reported to eCHIRPP, and 95% confidence intervals (CI). A total of 3,970 SRHIs were reported to eCHIRPP. Injuries were from contact with another player, the ball, ground, goal-post, and other causes. Of the injuries caused by contact with the ball, 9% were from purposely directing the ball with the head (heading). A higher proportion of concussions (PIR=1.32, 95% confidence interval [CI]: 1.27 to 1.37) and minor closed head injuries (PIR=1.20, 95% CI: 1.15 to 1.26) were observed in soccer players. Higher proportions of head injuries occurred in organized soccer and soccer played outdoors. However, admission to the ED for a SRHI was rare (PIR=0.40, 95% CI: 0.30 to 0.55). Overall, elevated proportions of brain injuries were observed among soccer players, however, these injuries were unlikely to result in a hospital admission. Moreover, purposely heading the ball contributed to few ED visits.
#5 Maturity-associated considerations for training load, injury risk, and physical performance within youth soccer: One size does not fit all
Reference: J Sport Health Sci. 2020 Sep 19;S2095-2546(20)30119-8. doi: 10.1016/j.jshs.2020.09.003. Online ahead of print.
Authors: Chris Towlson, Jamie Salter, Jack D Ade, Kevin Enright, Liam D Harper, Richard M Page, James J Malone
Summary: Biological maturation can be defined as the timing and tempo of progress to achieve a mature state. The estimation of age of peak height velocity (PHV) or percentage of final estimated adult stature attainment (%EASA) is typically used to inform the training process in young athletes. In youth soccer, maturity-related changes in anthropometric and physical fitness characteristics are diverse among individuals, particularly around PHV. During this time, players are also at an increased risk of sustaining an overuse or growth-related injury. As a result, the implementation of training interventions can be challenging. The purpose of this review is to (1) highlight and discuss many of the methods that can be used to estimate maturation in the applied setting and (2) discuss the implications of manipulating training load around PHV on physical development and injury risk. We also have provided key stakeholders with a practical online tool for estimating player maturation status (see online supplementary maturity estimation tool(s)). Whilst estimating maturity using predictive equations is useful in guiding the training process, practitioners should be aware of its limitations. To increase the accuracy and usefulness of data, it is also vital that sports scientists implement reliable testing protocols at predetermined time-points.
#6 The brains of elite soccer players are subject to experience-dependent alterations in white matter connectivity
Reference: Cortex. 2020 Sep 1;132:79-91. doi: 10.1016/j.cortex.2020.07.016. Online ahead of print.
Authors: Zai-Fu Yao, Ilja G Sligte, David Moreau, Shulan Hsieh, Cheng-Ta Yang, K Richard Ridderinkhof, Neil G Muggleton, Chun-Hao Wang
Summary: Soccer is the only major sport with voluntary unprotected head-to-ball contact. It is crucial to determine if head impact through long-term soccer training is manifested in brain structure and connectivity, and whether such alterations are due to sustained training per se. Using diffusion tensor imaging, we documented a comprehensive view of soccer players' brains in a sample of twenty-five right-handed male elite soccer players aged from 18 to 22 years and twenty-five non-athletic controls aged 19-24 years. Importantly, none had recalled a history of concussion. We performed a whole-brain tract-based spatial statistical analysis, and a tract-specific probabilistic tractography method to measure the differences of white matter properties between groups. Whole-brain integrity analysis showed stronger microstructural integrity within the corpus callosum tract in soccer players compared to controls. Further, tract-specific probabilistic tractography revealed that the anterior part of corpus callosum may be the brain structure most relevant to training experience, which may put into perspective prior evidence showing corpus callosum alteration in retired or concussed athletes practicing contact sports. Intriguingly, experience-related alterations showed left hemispheric lateralization of potential early signs of concussion-like effects. In sum, we concluded that the observed gains and losses may be due to a consequence of engagement in protracted soccer training that incurs prognostic hallmarks associated with minor injury-induced neural inflammation.
#7 Player load in male elite soccer: Comparisons of patterns between matches and positions
Reference: PLoS One. 2020 Sep 21;15(9):e0239162. doi: 10.1371/journal.pone.0239162. eCollection 2020.
Authors: Terje Dalen, Tore Kristian Aune, Geir Håvard Hjelde, Gertjan Ettema, Øyvind Sandbakk, David McGhie
Download link: https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0239162&type=printable
Summary: Our primary aim was to explore the development of player load throughout match time (i.e., the pattern) using moving 5-min windows in an elite soccer team and our secondary aim was to compare player load patterns between different positions within the same team. The dataset included domestic home matches (n = 34) over three seasons for a Norwegian Elite League team. Player movements (mean ± SD age 25.5 ± 4.2 years, height 183.6 ± 6.6 cm, body mass 78.9 ± 7.4 kg) were recorded at 20 Hz using body-worn sensors. Data for each variable (player load, player load per meter, total distance, accelerations, decelerations, sprint distance, high-intensity running distance) were averaged within positions in each match, converted to z-scores and averaged across all matches, yielding one time series for each variable for each position. Pattern similarity between positions was assessed with cross-correlations. Overall, we observed a distinct pattern in player load throughout match time, which also occurred in the majority of individual matches. The pattern shows peaks at regular intervals (~15 min), each followed by a period of lower load, declining until the next peak. The same pattern was evident in player load per meter. The cross-correlation analyses support the visual evidence, with correlations ranging 0.88-0.97 (p < .001) in all position pairs. In contrast, no specific patterns were discernible in total distance, accelerations, decelerations, sprint distance and high-intensity running distance, with cross-correlations ranging 0.65-0.89 (p < .001), 0.32-0.64 (p < .005), 0.18-0.65 (p < .005 in nine position pairs), 0.02-0.38 (p < .05 in three pairs) and 0.01-0.52 (p < .05 in three pairs), respectively. This study demonstrated similarity in player load patterns between both matches and positions in elite soccer competition, which could indicate a physical "pacing pattern" employed by the team.
#8 The validity of small-sided games in predicting 11-vs-11 soccer game performance
Reference: PLoS One. 2020 Sep 21;15(9):e0239448. doi: 10.1371/journal.pone.0239448. eCollection 2020.
Authors: Tom L G Bergkamp, Ruud J R den Hartigh, Wouter G P Frencken, A Susan M Niessen, Rob R Meijer
Download link: https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0239448&type=printable
Summary: Predicting performance in soccer games has been a major focus within talent identification and development. Past research has mainly used performance levels, such as elite vs. non-elite players, as the performance to predict (i.e. the criterion). Moreover, these studies have mainly focused on isolated performance attributes as predictors of soccer performance levels. However, there has been an increasing interest in finer grained criterion measures of soccer performance, as well as representative assessments at the level of performance predictors. In this study, we first determined the degree to which 7-vs-7 small-sided games can be considered as representative of 11-vs-11 games. Second, we assessed the validity of individual players' small-sided game performance in predicting their 11-vs-11 game performance on a continuous scale. Moreover, we explored the predictive validity for 11-vs-11 game performance of several physiological and motor tests in isolation. Sixty-three elite youth players of a professional soccer academy participated in 11 to 17 small-sided games and six 11-vs-11 soccer games. In-game performance indicators were assessed through notational analysis and combined into an overall offensive and defensive performance measure, based on their relationship with game success. Physiological and motor abilities were assessed using a sprint, endurance, and agility test. Results showed that the small-sided games were faster paced, but representative of 11-vs-11 games, with the exception of aerial duels. Furthermore, individual small-sided game performance yielded moderate predictive validities with 11-vs-11 game performance. In contrast, the physiological and motor tests yielded small to trivial relations with game performance. Altogether, this study provides novel insights into the application of representative soccer assessments and the use of continuous criterion measures of soccer performance.
#9 Match metabolic power over different playing phases in a young professional soccer team
Reference: J Sports Med Phys Fitness. 2020 Aug;60(8):1170-1171. doi: 10.23736/S0022-4707.20.10879-X.
Authors: Andrea Licciardi, Gabriele Grassadonia, Andrea Monte, Luca P Ardigò
Summary: To fully describe soccer match-play metabolic demands, we must consider the different playing phases and namely ball possession (Wp), non-possession (Wnp), and inactive
(Bi). Therefore, we aimed at estimating metabolic expenditure featuring the different playing phases by using GPS devices on 21 young players. Metabolic powers and playing phases collection was
carried out by using GPS receivers and applying the “metabolic-GPS” approach. Match average metabolic powers resulted significantly different over different playing phases (p=0.008 and d=0.67,
moderate). In particular match metabolic powers resulted higher during Wp and Wnp compared with Bi. During victories (V) compared with losses (L), Wp match average metabolic power resulted lower,
while Bi power resulted higher. Our measured total distances covered per match (TD) resulted lower during Vs – significantly compared with draws and not significantly compared with Ls. We can
hypothesize that 1) Wp is a team’s very demanding task and V can be achieved by limiting it as much as possible and 2) V can be achieved by limiting TDs as much as possible. Accurate soccer
workload assessment over both training and matches confirms to be relevant for players physical performance assessment and physical preparation optimization.
#10 Short-term effects of maximal dynamic exercise on flow-mediated dilation in professional female soccer players
Reference: J Sports Med Phys Fitness. 2020 Aug;60(8):1159-1166. doi: 10.23736/S0022-4707.20.10681-9.
Authors: Daniela K Andaku, Bruno Archiza, Flávia R Caruso, Renata Trimer, André C Amaral, José C Bonjorno Jr, Claudio R de Oliveira, Shane A Phillips, Ross Arena, Audrey Borghi-Silva
Summary: Endothelial function assessment may provide important insights into the cardiovascular function and long-term effects of exercise training. Many studies have investigated the possible negative effects on cardiovascular function due to extreme athletic performance, leading to undesirable effects. The purposes of this study were to investigate the acute effects of maximal intensity exercise on endothelium-dependent vasodilation, and to understand the patterns of flow-mediated dilation (FMD) change following maximal exercise in elite female athletes with a high-volume training history. Twenty-six elite female soccer players (mean age, 22±4 years; BMI, 21±2 kg/m<sup>2</sup>; VO<inf>2max</inf>, 41±4 mL/kg/min) were evaluated. Brachial artery FMD was determined using high-resolution ultrasound at rest, and after 15 and 60 min of maximal cardiopulmonary exercise (CPX) testing on a treadmill. Flow velocity was measured at baseline and during reactive hyperemia at the same periods. Rest FMD was 12.4±5.5%. Peak diameter in response to reactive hyperemia was augmented after 15 min of CPX (3.5±0.4 vs. 3.6±0.4 mm, P<0.05), returning to resting values after 60 min. However, %FMD did not change among time periods. There were two characteristic patterns of FMD response following CPX. Compared to FMD at rest, half of the subjects responded with an increased FMD following maximum exercise (10.5±6.1 vs. 17.8±7.5%, P<0.05). The other subjects demonstrated a reduced FMD response following maximum exercise (14.2±4.3 vs. 10.9±3.2%, P<0.01). These results indicate that elite female soccer players presented robust brachial artery FMD at rest, with a heterogeneous FMD response to acute exercise with a 50% FMD improvement rate.
#11 Gender differences in instep soccer kicking biomechanics, investigated through a 3D human motion tracker system
Reference: J Sports Med Phys Fitness. 2020 Aug;60(8):1072-1080. doi: 10.23736/S0022-4707.20.10676-5.
Authors: Bruno Ruscello, Mario Esposito, Gianmarco Siligato, Laura Lunetta, Lorenzo Marcelli, Laura Pantanella, Paolo R Gabrielli, Stefano D'ottavio
Summary: This study aims at describing and comparing each other male and female soccer players kicking instep a stationary ball. The different measures we collected by the 3D motion capture system Movit G1 and the High-Speed Camera (240 fps) were considered as dependent variables, whereas the gender was considered as the independent one. Twenty soccer well trained non-professional players: 10 men (age: 25.3±6.5 yrs; height 1.80±0.07 m; body mass 76.9±13.2 kg) and 10 women (age: 19±3.34 yrs; height 1.64±0.07 m; body mass 58.2±7.2 kg) volunteered to participate in the study. Gender differences were found, with a statistical significance (P<0.05) or interesting magnitude (Cohen d>0.5). The most relevant ones were the differences in hip extension of the kicking leg when the foot of the supporting one touches the ground, just before the impact on the ball (independent sample t-Test; P=0.03; Cohen d=1.64) and the speed of the ball, reached immediately after kicking (P<0.001;d=1.23). These results, together with the greater pelvic acceleration shown by men compared to women, highlight the need to develop a gender-differentiated training model, in order to customize the kicking technique in women and to reduce the likelihood, currently higher than for men, of kicking related injuries.
#12 Reducing Injuries in Soccer (Football): an Umbrella Review of Best Evidence Across the Epidemiological Framework for Prevention
Reference: Sports Med Open. 2020 Sep 21;6(1):46. doi: 10.1186/s40798-020-00274-7.
Authors: Oluwatoyosi B A Owoeye, Mitchell J VanderWey, Ian Pike
Download link: https://sportsmedicine-open.springeropen.com/track/pdf/10.1186/s40798-020-00274-7
Summary: Soccer is the most popular sport in the world. Expectedly, the incidence of soccer-related injuries is high and these injuries exert a significant burden on individuals and families, including health and financial burdens, and on the socioeconomic and healthcare systems. Using established injury prevention frameworks, we present a concise synthesis of the most recent scientific evidence regarding injury rates, characteristics, mechanisms, risk and protective factors, interventions for prevention, and implementation of interventions in soccer. In this umbrella review, we elucidate the most recent available evidence gleaned primarily from systematic reviews and meta-analyses. Further, we express the exigent need to move current soccer injury prevention research evidence into action for improved player outcomes and widespread impact through increased attention to dissemination and implementation research. Additionally, we highlight the importance of an enabling context and effective implementation strategies for the successful integration of evidence-based injury prevention programs into real-world soccer settings. This narrative umbrella review provides guidance to inform future research, practice, and policy towards reducing injuries among soccer players.
#13 Correlation of T2* relaxation times of the retropatellar cartilage with tibial tuberosity-trochlea groove distance in professional soccer players
Reference: Sci Rep. 2020 Sep 18;10(1):15355. doi: 10.1038/s41598-020-72299-7.
Authors: Kai-Jonathan Maas, M Warncke, C Behzadi, G H Welsch, G Schoen, M G Kaul, G Adam, P Bannas, F O Henes
Download link: https://www.nature.com/articles/s41598-020-72299-7.pdf
Summary: The tibial tuberosity-trochlear groove (TT-TG) distance is a radiographic measurement that is used to quantify malalignment of the patellofemoral joint (PFJ) in cross-sectional imaging. There is an ongoing debate about the impact of the TT-TG-distance on lateral patellar instability and the initiating of cartilage degeneration. In this prospective study, the association of T2* relaxation times and TT-TG distances in professional soccer players was analyzed. 36 knees of 18 professional soccer players (age: 21 ± 2.8 years) were evaluated. Participants underwent knee MRI at 3 T. For qualitative image analysis, fat-saturated 2D PD-weighted Fast Spin Echo (FSE) and T1-weighted FSE sequences were used. For quantitative analysis, T2* measurements in 3D data acquisitions were performed. In a qualitative analysis there was no structural cartilage damage and no abnormalities of the patellar and trochlea shape. The highest T2* values (26.7 ± 5.9 ms) were observed in the central compartment of the patella. The mean TT-TG distance was 10 ± 4 mm (range 3-20 mm). There was no significant correlation between TT-TG distance and T2* relaxation times in all three compartments of the retropatellar cartilage. Our study shows that so long as patellar and trochlear morphology is normal, TT-TG distance alone does not affect the tissue structure of the retropatellar cartilage in professional soccer players.
#14 Differential Ratings of Perceived Match and Training Exertion in Girls' Soccer
Reference: Int J Sports Physiol Perform. 2020 Sep 18;1-9. doi: 10.1123/ijspp.2019-0595. Online ahead of print.
Authors: Matthew D Wright, Francisco Songane, Stacey Emmonds, Paul Chesterton, Matthew Weston, Shaun J Mclaren
Summary: The aim was to understand the validity of differential ratings of perceived exertion (dRPE) as a measure of girls’ training and match internal loads. Using the centiMax scale (CR100), session dRPE for breathlessness (sRPE-B) and leg muscle exertion (sRPE-L) were collected across a season of training (soccer, resistance, and fitness) and matches from 33 players (15  y). Differences and associations between dRPE were examined using mixed and general linear models. The authors’ minimal practical important difference was 8 arbitrary units (AU). Mean (AU [SD] ∼16) sRPE-B and sRPE-L were 66 and 61 for matches, 51 and 49 for soccer, 86 and 67 for fitness, and 45 and 58 for resistance, respectively. Session RPE-B was rated most likely harder than sRPE-L for fitness (19 AU; 90% confidence limits: ±7) and most likely easier for resistance (−13; ±2). Match (5; ±4) and soccer (−3; ±2) differences were likely to most likely trivial. The within-player relationships between sRPE-B and sRPE-L were very likely moderate for matches (r = .44; 90% confidence limits: ±.12) and resistance training (.38; ±.06), likely large for fitness training (.51; ±.22), and most likely large for soccer training (.56; ±.03). Shared variance ranged from 14% to 35%. Practically meaningful differences between dRPE following physical training sessions coupled with low shared variance in all training types and matches suggest that sRPE-B and sRPE-L represent unique sensory inputs in girls’ soccer players. The data provide evidence for the face and construct validity of dRPE as a measure of internal load in this population.
This study analyses the differential perceived match load accumulated by professional soccer players depending on participation in several consecutive matches.
This study aims to quantify and analyze the differences in position-specific performances in games played with three or four defensive players.
Following studies were retrieved for this week:
#1 Effects of Combined Power Band Resistance Training on Sprint Speed, Agility, Vertical Jump Height, and Strength in Collegiate Soccer
Reference: Int J Exerc Sci. 2020 Aug 1;13(4):950-963. eCollection 2020.
Authors: Edgar T Katushabe, Mark Kramer
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7449328/pdf/ijes-13-4-950.pdf
Summary: Soccer involves explosive physical actions requiring strength, power, and agility for optimal performance. Such attributes may be trained several ways, of which power-band resistance training has received limited attention regarding the potential for performance improvement in soccer players. This study serves to determine the effect of power-band resistance training on 1-repetition maximal (1RM) strength, speed, standing vertical jump (SVJ) height, and agility of collegiate soccer players. Seventeen male players (age: 20.47 ± 1.85 years, height: 1.77 ± 0.08 m, mass: 70.49 ± 4.15 kg) were matched and randomly allocated into either a conventional resistance group (CON, n = 8), or a power-band resistance training group (EXP, n = 9). Following a 6-week intervention, participants were re-assessed relative to their baseline values, showing improvements in 1RM squat mass (CON: +31.57%; EXP: +34.61%), 1RM deadlift mass (CON: +15.44%; EXP: +13.72%), and SVJ height (CON: +4.15%; EXP: +6.35%). Power-band resistance training produced greater results compared to conventional training in 1RM squat mass, even when between-group baseline values were controlled for (ANCOVA, F(1,14)=5.32, p = 0.037, η2p=.28). No other between-group differences were evident, showing no clear methodological superiority. Power-band resistance training shows potential as an effective training methodology compared to conventional resistance training to improve performance variables in university soccer players.
#2 Perception of Affordances in Soccer: Kicking for Power Versus Kicking for Precision
Reference: Res Q Exerc Sport. 2020 Sep 14;1-9. doi: 10.1080/02701367.2020.1812494. Online ahead of print.
Authors: Alper Tunga Peker, Veysel Böge, George Bailey, Jeffrey B Wagman, Thomas A Stoffregen
Summary: We investigated youth soccer players' perception of affordances for different types of kicks. In the Power task, players judged the maximum distance they could kick the ball. In the Precision task, players judged how close to a designated target line they could kick the ball. Following judgments, players performed each task. Both judgments and performance were assessed immediately before and immediately after players competed in a regulation soccer match, thereby permitting us to assess possible effects of long-term experience on perceptual sensitivity to short-term changes in ability. We compared players from two league groups: U16 (mean age = 15.45 years, SD = 0.52 years) versus U18 (mean age = 17.55 years, SD = 0.52 years). As expected, for the Power task actual kicking ability was greater for the U18 group (p < .05). In statistically significant interactions, we found that judgments of Power kicking ability differed before versus after match play, but only for the U16 group. We found no statistically significant effects for the Precision task. We identified interactions between long-term and short-term soccer experience which revealed that the effects of long-term experience on affordance perception were not general. Two additional years of playing experience (in the U18 group, relative to the U16 group) did not lead to an overall improvement in the perception of kicking-related affordances. Rather, variation in long-term experience was associated with changes in affordance perception which were situation-specific, being manifested only after playing a soccer match, and not before.
#3 Comparisons of Accelerometer Variables Training Monotony and Strain of Starters and Non-Starters: A Full-Season Study in Professional Soccer Players
Reference: Int J Environ Res Public Health. 2020 Sep 9;17(18):E6547. doi: 10.3390/ijerph17186547.
Authors: Hadi Nobari, Rafael Oliveira, Filipe Manuel Clemente, Jose Carmelo Adsuar, Jorge Pérez-Gómez, Jorge Carlos-Vivas, João Paulo Brito
Download link: https://www.mdpi.com/1660-4601/17/18/6547/pdf
Summary: The purpose of this study was two-fold: (1) to describe weekly average values for training monotony (TM) and training strain (TS) and their variations across the full soccer season, based on the number of accelerations and decelerations; (2) to analyze the differences between starter and non-starter players on weekly average TM and TS values for the pre-season and three in-season periods. In total, 21 professional soccer players were evaluated over 48 weeks during the full-season. The TM and TS were calculated based on the number of accelerations and decelerations at zone 1, zone 2 and zone 3, respectively. The results revealed that starters presented higher values compared to non-starters throughout the full season for all variables analyzed (all, p < 0.05). Generally, there were higher values in the pre-season. Specifically, accelerations at zones 1, 2 and 3 revealed moderate to very large significance of the starters compared to non-starters over the full-season. Decelerations at zone 1, 2 and 3 presented moderate to nearly optimally significant greater weekly averages for starters compared to non-starters during the full season. In conclusion, the TM and TS values were higher for starters compared to non-starters through the full-season, which confirms that the training session does not provide a sufficient load to non-starter soccer players during the full-season.
#4 Anxiety and Depressive Symptoms During the COVID-19 Emergency Period: A Comparative Cross-Sectional Study in Professional Football
Reference: Clin J Sport Med. 2020 Sep 15. doi: 10.1097/JSM.0000000000000886. Online ahead of print.
Authors: Vincent Gouttebarge, Imtiaz Ahmad, Margo Mountjoy, Simon Rice, Gino Kerkhoffs
Summary: The primary objective of our study was to establish the prevalence of anxiety and depressive symptoms among professional football (ie, soccer; hereinafter "football") players during the COVID-19 emergency period, drawing comparisons with players assessed before exposure to the COVID-19 emergency period. A total of 468 female (mean age: 22.8 years) and 1134 male (mean age: 26.0 years) players participated in this study. The non-COVID-19 comparison group consisted of 132 female (mean age: 23.1 years) and 175 male (mean age: 24.8 years) professional footballers. Anxiety symptoms were measured with the validated Generalized Anxiety Disorder 7 and depressive symptoms with the validated Patient Health Questionnaire 9. Both instruments have been widely used in both clinical and research settings among different populations, showing excellent psychometric properties. During the COVID-19 emergency period, the 2-week prevalence of symptoms consistent with a diagnosis of generalized anxiety disorder and depression was 18.2% and 21.6%, respectively, among female professional footballers and 15.5% and 12.9%, respectively, among male players. The 2-week prevalence of anxiety and depressive symptoms among professional footballers was significantly higher during the COVID-19 emergency period than before the global pandemic (P < 0.01). Differences were most pronounced for those worried about the playing future. The COVID-19 emergency period is associated with increased symptoms of anxiety and depression in professional footballers, especially among those worried about their future as players.
#5 Deconstructing celebratory acts following goal scoring among elite professional football players
Reference: PLoS One. 2020 Sep 16;15(9):e0238702. doi: 10.1371/journal.pone.0238702. eCollection 2020.
Authors: Assaf Lev, Yair Galily, Omer Eldadi, Gershon Tenenbaum
Download link: https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0238702&type=printable
Summary: Goal celebration in sport is mostly spontaneous and is manifested via vocal expressions and bodily gestures aimed at communicating emotions. The aim of this study is to deconstruct the celebratory acts among elite professional football players in the European Champions League following scoring a goal, and to capture the multiple acts and functions of the celebrations. In examining the 2018/19 season of the European Champions League tournament, we draw attention to the players' celebrations and their corresponding social and individual functions. All goals/celebrations (K = 366) were used for the analyses. To analyze the goal celebration acts, a socio-psychological model was established which is comprised of several theories. To describe the goal celebration acts across the competition stages (e.g., preliminary and final), match location (i.e., home or away), time phase (0-15, 15-45, 45-75, 75-90, 90+ minutes), scoring mode (i.e., prior to the goal, after the goal), and players' continent origin (Europe, Africa, Asia, South/Central, and North America), the number and percent of all the celebratory acts were counted and presented in their respective mode (i.e., single, double, and team). The main findings indicate that (a) most of the goal celebration acts were performed interactively by the scoring player and his teammates, (b) the interactive modes of celebration lasted longer than the modes which were performed non-interactively, (c) the celebration lasted longer following goal scoring in the final stage than in the preliminary stage, (d) the celebration duration lasted the longest time when the goal was scored during the overtime phase (90+ min) of the final but not the preliminary stage, and (e) players from Africa and South America demonstrated religious acts more than their European counterparts. We assert that our conceptual model enables the categorization of a variety of personal and social meanings to the celebrations on the field during the most thrilling moments of the game.
#6 Passing Networks and Tactical Action in Football: A Systematic Review
Reference: Int J Environ Res Public Health. 2020 Sep 11;17(18):E6649. doi: 10.3390/ijerph17186649.
Authors: Sergio Caicedo-Parada, Carlos Lago-Peñas, Enrique Ortega-Toro
Download link: https://www.mdpi.com/1660-4601/17/18/6649/pdf
Summary: The aim of this study is to examine the most significant literature on network analyses and factors associated with tactical action in football. A systematic review was conducted on Web of Science, taking into account the PRISMA guidelines using the keyword "network", associated with "football" or "soccer". The search yielded 162 articles, 24 of which met the inclusion criteria. Significant results: (a) 50% of the studies ratify the importance of network structures, quantifying and comparing properties to determine the applicability of the results instead of analyzing them separately; (b) 12.5% analyze the process of offensive sequences and communication between teammates by means of goals scored; (c) the studies mainly identify a balance in the processes of passing networks; (d) the variables allowed for the interpretation of analyses of grouping metrics, centralization, density and heterogeneity in connections between players of the same team. Finally, a systematic analysis provides a functional understanding of knowledge that will help improve the performance of players and choose the most appropriate response within the circumstances of the game.
#7 Effect of football activity and physical fitness on information processing, inhibitory control and working memory in adolescents
Reference: BMC Public Health. 2020 Sep 14;20(1):1398. doi: 10.1186/s12889-020-09484-w.
Authors: Ryan A Williams, Simon B Cooper, Karah J Dring, Lorna Hatch, John G Morris, Caroline Sunderland, Mary E Nevill
Download link: https://bmcpublichealth.biomedcentral.com/track/pdf/10.1186/s12889-020-09484-w
Summary: Whilst an acute bout of exercise has been shown to enhance subsequent cognition, including in adolescents, the effects of team games (of which Football is the most popular) has received little attention. Therefore, this study examined: the effect of an acute bout of outdoor Football activity on information processing, inhibitory control, working memory and circulating brain-derived neurotrophic factor (BDNF) in adolescents; the effect of physical fitness on cognition and; the moderating effect of physical fitness on the acute exercise responses. Following familiarisation, 36 adolescents (16 girls) took part in two trials (60-min Football and 60-min seated rest) separated by 7-d in a counterbalanced, crossover design. Information processing and inhibitory control (Stroop Test), and working memory (Sternberg Paradigm) were assessed 30-min before exercise/rest and immediately, 45- and 90-min post-exercise/rest. Capillary blood samples were obtained before exercise/rest and up to 120-min post-exercise/rest. The median split of distance covered on the MSFT was used to divide the group into high- and low-fit groups. Performance on the cognitive function tasks was similar between Football and seated rest (trial*time interactions; all p > .05). However, the high-fit group had overall quicker response times on both levels of the Stroop Task and all three levels of the Sternberg Paradigm (main effect of fitness; all p < .001). Furthermore, the exercise-cognition relationship was moderated by physical fitness, with improvements in working memory response times seen post-exercise, only in the high-fit group (trial*time*fitness interaction, p < .05). Circulating BDNF was unaffected by the Football activity and physical fitness (p > .05). The present study shows that higher levels of physical fitness are beneficial for cognitive function and provides novel evidence that an ecologically valid, and popular, form of exercise is beneficial for working memory following exercise, in high-fit participants only.
#8 Game format alters the physiological and activity demands encountered during small-sided football games in recreational players
Reference: J Exerc Sci Fit. 2021 Jan;19(1):40-46. doi: 10.1016/j.jesf.2020.05.001. Epub 2020 May 28.
Authors: Emilija Stojanović, Nenad Stojiljković, Ratko Stanković, Aaron T Scanlan, Vincent J Dalbo, Zoran Milanović
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7475126/pdf/main.pdf
Summary: Conditioning in the form of football small-sided games (SSG) is being increasingly utilized as a health-promoting and performance-enhancing activity. The aim of this study was to quantify and compare the physiological responses and activity demands encountered during 3-a-side, 4-a-side, and 5-a-side football SSG in recreational players. Heart rate, blood lactate (BLa), rating of perceived exertion (RPE) and activity demands were measured across 2 × 20-min football sessions played on a 40 × 20-m pitch in 12 recreationally active college students. Data were collected over a period of two weeks using a repeated-measures crossover design. Mean heart rate was higher (moderate) during 5-a-side than 4-a-side (p = 0.02) and 3-a-side SSG (p < 0.001). BLa tended to be higher (small) in 3-a-side compared to 4-a-side (p = 0.12) and 5-a-side SSG (p = 0.46). The total distance covered was lower (large) during 5-a-side than 4-a-side SSG (p = 0.02), while the total number of accelerations (p = 0.01) and decelerations (p = 0.02) were higher (large) during 5-a-side than 4-a-side SSG. These data suggest: 1) 5-a-side SSG require a greater intermittent workload and exacerbated HR responses; 2) 4-a-side SSG require more sustained activity (distance); and 3) 3-a-side SSG result in higher BLa compared to other SSG formats. The observed intermittent workload and exacerbated HR response in 5-a-side SSG were likely due to greater turnover rates with more frequent interceptions. Sustained activity in 4-a-side SSG might be underpinned by format-specific structures permitting optimal team work, while isolated guarding of players in 3-a-side SSG may have exacerbated BLa responses.
#9 The prevalence of non-contact muscle injuries of the lower limb in professional soccer players who perform Salah regularly: a retrospective cohort study
Reference: J Orthop Surg Res. 2020 Sep 24;15(1):440. doi: 10.1186/s13018-020-01955-5.
Authors: Eduard Bezuglov, Oleg Talibov, Mikhail Butovskiy, Anastasiya Lyubushkina, Vladimir Khaitin, Artemii Lazarev, Evgeny Achkasov, Zbigniew Waśkiewicz, Thomas Rosemann, Pantelis T Nikolaidis, Beat Knechtle, Nicola Maffulli
Download link: https://josr-online.biomedcentral.com/track/pdf/10.1186/s13018-020-01955-5
Summary: The present study assessed the prevalence of non-contact muscle injuries of the lower limbs, including hamstring injuries, in professional Russian soccer players who regularly perform Salah, an obligatory Muslim prayer performed 5 times a day. Using a retrospective cohort study design, 68 professional male soccer players (excluding goalkeepers), 34 of whom were Muslims regularly performing Salah (exposure group) and 34 were randomly chosen non-Muslim players (control group), were included in the study. The groups were similar in their playing leagues, field positions, age (27 ± 3.1 vs 28 ± 4.2 years), and body mass index (22 ± 1.2 vs 23 ± 0.92 kg/m2). The incidence of hamstring injury was significantly lower in the exposure group (2 vs 14, p = 0.0085). A declining trend for the number of muscle injuries (either hamstring or not) was observed in the exposure group (11 vs 27, p = 0.0562). Two players in the exposure group and 11 in the control group (p = 0.0115, OR 0.1307, 95% CI 0.0276 to 0.5698) suffered a hamstring injury, with no statistically significant difference in the occurrence of other injuries. The total amount of the training and play days missed because of hamstring and other muscle injuries was significantly lower in the exposure group (24 vs 213 days, p = 0.0043, and 200 vs 344 days, p = 0.0066, respectively). The prevalence of non-contact muscle injuries, including hamstring injuries, was lower in professional Russian soccer players who regularly performed Salah.
#10 Effects of Tetraselmis chuii Microalgae Supplementation on Ergospirometric, Haematological and Biochemical Parameters in Amateur Soccer Players
Reference: Int J Environ Res Public Health. 2020 Sep 21;17(18):E6885. doi: 10.3390/ijerph17186885.
Authors: Víctor Toro, Jesús Siquier-Coll, Ignacio Bartolomé, María C Robles-Gil, Javier Rodrigo, Marcos Maynar-Mariño
Download link: https://www.mdpi.com/1660-4601/17/18/6885/pdf
Authors: This study aimed to analyse the effects of Tetraselmis chuii (TC) microalgae supplementation during thirty days on ergospirometric, haematological and biochemical parameters in amateur soccer players. Thirty-two amateur soccer players divided into a control group (CG; n = 16; 22.36 ± 1.36 years; 68.36 ± 3.53 kg) and a supplemented group (SG; n = 16; 22.23 ± 2.19 years; 69.30 ± 5.56 kg) participated in the double-blind study. SG ingested 200 mg of the TC per day, while CG ingested 200 mg per day of lactose powder. Supplementation was carried out for thirty days. The participants performed a maximal treadmill test until exhaustion. The ergospirometric values at different ventilatory thresholds and haematological values were obtained after the test. Heart rate decreased after supplementation with TC (p < 0.05). Oxygen pulse, relative and absolute maximum oxygen consumption increased in SG (pre vs. post; 19.04 ± 2.53 vs. 22.08 ± 2.25; 53.56 ± 3.26 vs. 56.74 ± 3.43; 3.72 ± 0.35 vs. 3.99 ± 0.25; p < 0.05). Haemoglobin and mean corpuscular haemoglobin increased in SG (pre vs. post; 15.12 ± 0.87 vs. 16.58 ± 0.74 p < 0.01; 28.03 ± 1.57 vs. 30.82 ± 1.21; p < 0.05). On the other hand, haematocrit and mean platelet volume decreased in SG (p < 0.05). TC supplementation elicited improvements in ergospirometric and haematological values in amateur soccer players. TC supplementation could be valuable for improving performance in amateur athletes.
#11 Area per player in small-sided games to replicate the external load and estimated physiological match demands in elite soccer players
Reference: PLoS One. 2020 Sep 23;15(9):e0229194. doi: 10.1371/journal.pone.0229194. eCollection 2020.
Authors: Andrea Riboli, Giuseppe Coratella, Susanna Rampichini, Emiliano Cé, Fabio Esposito
Download link: https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0229194&type=printable
Summary: The current study determined the area-per-player during small- or large-sided games with or without goalkeeper that replicates the relative (m·min-1) total distance, high-intensity running distance, sprint distance and metabolic power covered during official matches. Time-motion analysis was performed on twenty-five elite soccer-players during 26 home-matches. A total of 2565 individual samples for SSGs using different pitch sizes and different number of players were collected and classified as SSGs with (SSG-G) or without goalkeeper (SSG-P). A between-position comparison was also performed. The area-per-player needed to replicate the official match demands was largely higher in SSG-G vs SSG-P for total distance [187±53 vs 115±35 m2, effect size (ES): 1.60 95%CI 0.94/2.21], high-intensity running distance [262±72 vs 166±39 m2, ES: 1.66(0.99/2.27)] and metabolic power [177±42 vs 94±40, ES: 1.99(1.31/2.67)], but similar for sprint distance [(316±75 vs 295±99 m2, ES: 0.24(-0.32/0.79)] with direction of larger area-per-player for sprint distance > high-intensity running > total distance ≌ metabolic power for both SSG-G and SSG-P. In SSG-G, forwards required higher area-per-player than central-defenders [ES: 2.96(1.07/4.35)], wide-midfielders [ES: 2.45(0.64/3.78)] and wide-defenders [ES: 3.45(1.13/4.99)]. Central-midfielders required higher area-per-player than central-defenders [ES: 1.69(0.20/2.90)] and wide-midfielders [ES: 1.35(-0.13/2.57)]. In SSG-P, central defenders need lower area-per-player (ES: -6.01/-0.92) to overall replicate the match demands compared to all other positions. The current results may be used to gain knowledge of the SSGs relative to the match demands. This imply manipulating SSGs using higher or lower ApP, the presence of the goalkeeper or design specific rules to increase or decrease the position-specific demands with respect to the desired external load outcomes.
#12 Effects of an Initial Muscle Strength Level on Sports Performance Changes in Collegiate Soccer Players
Reference: Sports (Basel). 2020 Sep 15;8(9):E127. doi: 10.3390/sports8090127.
Authors: Ai Ishida, Kyle Rochau, Kyle P Findlay, Brandon Devero, Marco Duca, Michael H Stone
Download link: https://www.mdpi.com/2075-4663/8/9/127/pdf
Summary: The purposes of this study were to investigate effects of partial block periodized strength training on physical performance and to examine relationships between initial muscle strength measured with isometric mid-thigh pull (IMTP) and performance changes after 7 weeks of strength training. Seventeen collegiate male soccer players participated. Initial muscle strength was determined using IMTP while physical performance included 10 m and 20 m sprints and static vertical jump with a polyvinyl chloride pipe (SJ0), 20 kg barbell (SJ20), and barbell loaded to 40 kg bar (SJ40). Performance testing was performed at three points: before first week (baseline), fourth week (T1), and seventh week (T2). Statistically small to moderate changes were found from baseline to T2 in peak power (PP; p < 0.001, ES = 0.49), net impulse (NI; p < 0.001, ES = 0.49), peak velocity (PV; p < 0.001, ES = 0.62), allometrically scaled PP (PPa; p < 0.001, ES = 0.62) in SJ20 and jump height (JH) in SJ40 (p < 0.001, ES = 0.36). Moderate to large correlations were found between isometric peak force and the changes from baseline to T2 in SJ20 PP (p = 0.04, r = -0.49), SJ20 PF (p = 0.03, r = -0.52), PPa (p = 0.04, r = -0.50), and SJ20 allometrically scaled peak force (p = 0.04, r = -0.49). Properly structured strength training maximizes task-specific physical performance. Initial muscle strength negatively affects the magnitudes of adaptations to physical performance.
The study assessed whether a new, closed-skill dribbling or sprinting task could predict attacking performance.
The aims of the study were to determine the effectiveness of indirect free kicks, identify variables associated with a successful outcome.
Following studies were retrieved for this week:
#1 Effect of skill-based training vs. small-sided games on physical performance improvement in young soccer players
Reference: Biol Sport. 2020 Sep;37(3):305-312. doi: 10.5114/biolsport.2020.96319. Epub 2020 Jun 26.
Authors: Mustafa Karahan
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7433329/pdf/JBS-37-96319.pdf
Summary: Recently, there has been increasing attention to research related to the effect of skill-based or game-based training on soccer players' physical performance. Therefore, this study aimed to compare the effectiveness of skill-based training (SBT) at maximum intensity versus the small-sided game (SSG) on the physical performance characteristics of young soccer players during the pre-season period. Twenty-two male soccer players (mean age 15.3 ± 3 years) were randomly assigned to either an SBT or SSG fully controlled intervention programme, running parallel for eight weeks and held twice a week. On three non-consecutive days before and after training players completed a test battery consisting of the 20 m sprint, T-run, countermovement jump, running anaerobic sprint test (RAST) and 20 m shuttle run. Data were analysed with a two-way ANOVA test for repeated measures. SBT and SSG interventions induced a significant improvement in the anaerobic power (10.9% vs 6.2%), explosive power (8.5% vs 5.6%), VO2max (6.7% vs 6.5%) and vertical jump (5.3% vs 2.9%), respectively. When the improvements in the physical performance variables of both groups are compared, the SBT group achieved greater improvement than the SSG group in anaerobic power (by 4.7%), in explosive power (by 2.8%), in vertical jumping (by 2.3%), in the 20 m sprint (by 2.2%) and T-test scores (by 1.7%). However, improvements in the VO2max were similar in both groups. The results of the present study suggest that SBT at maximum intensity may be more effective than SSG in improving the physical performance characteristics of young soccer players in the pre-competitive season.
#2 Curve sprinting in soccer: relationship with linear sprints and vertical jump performance
Reference: Biol Sport. 2020 Sep;37(3):277-283. doi: 10.5114/biolsport.2020.96271. Epub 2020 Jun 9.
Authors: Irineu Loturco, Lucas A Pereira, Alberto Fílter, Jesús Olivares-Jabalera, Valter P Reis, Victor Fernandes, Tomás T Freitas, Bernardo Requena
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7433323/pdf/JBS-37-96271.pdf
Summary: We examined the relationships among linear speed, vertical jumping ability and curve sprint (CS) performance. Moreover, the correlations between linear and curvilinear sprint velocities and CS deficit were tested. Twenty-eight under-20 soccer players performed squat and countermovement jumps, 17-m linear sprint (with split times at 5 and 10 m), and a CS test for both sides. For the first time, the new proposed CS deficit was calculated as the difference between 17-m velocity and CS test velocity. Pearson's product moment of correlation was performed to determine the relationships among the distinct variables tested. Significance level was set at P < 0.05. Large to very large relationships between linear sprint speed and CS performance were observed, on both the "good" and "weak" sides. In addition, moderate to large correlations between linear and curve sprint abilities and vertical jumps were found. Finally, the CS deficit was negatively associated with the CS good side performance. Linear sprint and CS velocities for both good and weak sides were closely related. The CS deficit was only related to the CS weak side performance, and the vertical jumping ability was significantly associated with both linear and curvilinear sprint velocities. The present results suggest that training methods capable of improving linear sprint and vertical jumping abilities may also improve CS performance.
#3 Changes in γH2AX and H4K16ac levels are involved in the biochemical response to a competitive soccer match in adolescent players
Reference: Sci Rep. 2020 Sep 2;10(1):14481. doi: 10.1038/s41598-020-71436-6.
Authors: Katarzyna Kozioł, Jacek Zebrowski, Gabriela Betlej, Ewelina Bator, Wojciech Czarny, Wojciech Bajorek, Bartłomiej Czarnota, Robert Czaja, Paweł Król, Aleksandra Kwiatkowska
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7468116/pdf/41598_2020_Article_71436.pdf
Summary: The aim of this study was to examine novel putative markers of the response to the competitive soccer match in adolescent players, such as changes in global levels of γH2AX and H4K16ac in the chromatin of peripheral mononuclear blood cells (PMBCs) and a Fourier-transform infrared spectroscopy (FTIR)-based biochemical fingerprint of serum. These characteristics were examined with reference to the physiological and metabolic aspects of this response. Immediately post-match we noticed: (1) a systemic inflammatory response, manifesting as peaks in leukocyte count and changes in concentrations of IL-6, TNFα, and cortisol; (2) a peak in plasma lactate; (3) onset of oxidative stress, manifesting as a decline in GSH/GSSG; (4) onset of muscle injury, reflected in an increase in CK activity. Twenty-four hours post-match the decrease in GSH/GSSG was accompanied by accumulation of MDA and 8-OHdG, macromolecule oxidation end-products, and an increase in CK activity. No changes in SOD1 or GPX1 levels were found. Repeated measures correlation revealed several associations between the investigated biomarkers. The FTIR analysis revealed that the match had the greatest impact on serum lipid profile immediately post-game. In turn, increases in γH2AX and H4K16ac levels at 24 h post-match indicated activation of a DNA repair pathway.
#4 Prospective analysis of craniofacial soccer incidents during FIFA competitions: an observational study
Reference: Braz Oral Res. 2020;34:e106. doi: 10.1590/1807-3107bor-2020.vol34.0106. Epub 2020 Aug 28.
Authors: Mateus de Azevedo Kinalski, Kaue Collares, Marcos Britto Correa
Download link: https://www.scielo.br/pdf/bor/v34/1807-3107-bor-34-e106.pdf
Summary: The aim of this prospective epidemiological study was to evaluate the occurrence of incidents involving the craniofacial region of soccer players during three official FIFA competitions. The craniofacial incidents were identified by video analysis of all 144 matches of two FIFA World Cups (2014/2018) and the 2017 FIFA Confederations Cup. Data collection included incident type, incident severity, site affected, incident cause and referee decision. The multivariate Poisson regression model was performed to analyze the associations between covariates. A total of 238 incidents were observed in the craniofacial region (1.6 incidents/match), representing a rate of 48.5 incidents per 1000 hours. At least 80.6% of the matches presented at least one incident, and, in more than 60%, the referee's decision was no foul. According to severity, 26.8% of the incidents were classified as having mild or high severity. Incidents involving lacerations or fracture presented higher severity compared with hits (IRR 3.45[95%CI: 1.89-6.30]). Head-to-head impacts showed an incidence of severe incidents twice as high as those involving upper extremities (IRR 2.01[95%CI:1.07-3.76]). A high number of craniofacial incidents were observed in the last FIFA competitions. Head-to-head impacts and lacerations or fractures were associated with higher incident severity.
#5 Can A Superimposed Whole-Body Electromyostimulation Intervention Enhance the Effects of a 10-Week Athletic Strength Training in Youth Elite Soccer Players?
Reference: J Sports Sci Med. 2020 Aug 13;19(3):535-546. eCollection 2020 Sep.
Authors: Oliver Ludwig, Joshua Berger, Torsten Schuh, Marco Backfisch, Stephan Becker, Michael Fröhlich
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7429429/pdf/jssm-19-535.pdf
Summary: Strength training in youth soccer has both a preventive and a sports-specific component. Whole-body electromyostimulation (WB-EMS) could represent an interesting time-saving add-on to classical strength exercises in performance-oriented soccer. The objective of this study was to find out whether a 10-week superimposed WB-EMS training might have a more positive impact on strength parameters in male youth elite soccer players than regular athletic strength exercises alone. A total of 30 male youth soccer players from a youth academy aged 15 to 17 years participated in the study. Before and after the intervention, the isometric extension and flexion forces of trunk and knee, and the hip abduction and adduction forces were tested. Twelve players (control group) absolved a conventional 20-minute strength training once a week for a period of ten weeks. Eighteen players absolved the same exercises but with superimposed WB-EMS. Blood creatine kinase concentration was measured for training control. ANOVAs, Friedman tests and post hoc t-tests were calculated (p = 0.05) to examine the strength development during the training period between the groups. While we could not find significant strength increases in the leg, hip and trunk muscles in the control group (<4%), the strength of the WB-EMS group improved significantly in 4 of the 6 muscle groups tested. In this group, the strength of knee flexors increased significantly by 20.68 ± 21.55%, knee extensors by 31.43 ± 37.02%, hip adductors by 21.70 ± 12.86% and trunk flexors by 33.72 ± 27.43%. The rates of strength increase are partly in line with other studies, partly clearly higher, which might be explained by the athletically active target group. A 10-week superimposed WB-EMS training improves the strength of certain leg, hip and trunk muscles in male adolescent elite soccer players to a greater extent than a pure athletic strength training of the same duration.
#6 Can Haematological and Hormonal Biomarkers Predict Fitness Parameters in Youth Soccer Players? A Pilot Study
Reference: Int J Environ Res Public Health. 2020 Aug 29;17(17):E6294. doi: 10.3390/ijerph17176294.
Authors: Fabrizio Perroni, Silvia Migliaccio, Paolo Borrione, Mario Vetrano, Stefano Amatori, Davide Sisti, Marco B L Rocchi, Gerardo Salerno, Riccardo Del Vescovo, Elena Cavarretta, Laura Guidetti, Carlo Baldari, Vincenzo Visco
Download link: https://www.mdpi.com/1660-4601/17/17/6294/pdf
Summary: The study aimed to investigate the correlations among immune, haematological, endocrinological markers and fitness parameters, and assess if the physiological parameters could be a predictor of fitness values. Anthropometric, physical evaluations (countermovement jump-CMJ, 10 m sprint, VO2max, repeated sprint ability-RSA total time and index) and determination of blood (IL-6, IL-10, IL-17A and tumour necrosis factor) and salivary (testosterone and cortisol) samples parameters in 28 young male soccer players (age: 13.0 ± 0.2 years, body mass index (BMI): 19.5 ± 2.2 kg/m2) were analysed. To evaluate the dependence of the variables related to athletic performance, multiple linear regression with backward stepwise elimination was considered. A significant regression equation was found in CMJ (F(5,16) = 9.86, p < 0.001, R2 adjusted = 0.679) and in the RSA index (F(5,16) = 15.39, p < 0.001, R2 adjusted = 0.774) considering only five variables, in a 10 m sprint (F(4,17) = 20.25, p < 0.001, R2 adjusted = 0.786) and in the RSA total time (F(4,17) = 15.31, p < 0.001, R2 adjusted = 0.732) considering only four variables and in VO2max (F(9,12) = 32.09, p < 0.001, R2 adjusted = 0.930) considering nine variables. Our study suggests the use of regression equations to predict the fitness values of youth soccer players by blood and saliva samples, during different phases of the season, short periods of match congestion or recovery from an injury.
#7 Fair Play as an Injury Prevention Intervention: Do Yellow Card Accumulation Policies Reduce High School Soccer Injuries?
Reference: Clin J Sport Med. 2020 Sep 15. doi: 10.1097/JSM.0000000000000877. Online ahead of print.
Authors: Peter K Kriz, Jingzhen Yang, Alan Arakkal, Timothy Keeley, R Dawn Comstock
Summary: The objective was to Evaluate yellow card policies' (YCPs) effectiveness in reducing competition contact injuries (CCIs). Soccer players from High School (HS) Reporting Information Online participating schools, 2005/06 to 2017/18. Athlete exposure (AE), CCIs from HS competitions collected from states with/without YCPs were used as independent variables. Rate and rate ratio (RR) of athlete-athlete CCIs recorded by athletic trainers were compared between states with/without YCPs and pre-YCPs/post-YCPs among the states with YCPs using Poisson regressions. Proportions of severe athlete-athlete CCIs were also described in states with/without YCPs. Fifteen states implemented YCPs between 2005/06 and 2017/18; 901 athlete-athlete CCIs occurred during 352 775 competition AEs in states with YCPs, and 3525 injuries during 1 459 708 competition AEs in states without YCPs. There was no significant difference in injury rates between schools in states with/without YCPs (RR 1.07; 95% confidence interval [CI]: 0.97-1.17). Among state with YCPs, injury rates were not significantly different between pre-YCP and post-YCP implementation (RR 1.15; 95% CI: 0.98-1.34). Although a significantly lower proportion of injuries resulting in >3 weeks' time loss (TL) occurred in states with YCPs (injury proportion ratio 0.81; 95% CI: 0.66-0.997), no significant differences were observed in proportions of other severe athlete-athlete CCIs between states with/without YCPs. Yellow card policies were ineffective in lowering HS soccer athlete-athlete CCI rates, although injuries resulting in >3 weeks' TL were less prevalent in states with YCPs. Implementation of YCPs alone, without proper enforcement, may not be a sufficient injury prevention strategy.
#8 Sportomics in professional soccer players: metabolomics results during preseason
Reference: J Sports Med Phys Fitness. 2020 Sep 16. doi: 10.23736/S0022-4707.20.11200-3. Online ahead of print.
Authors: Roberta Pintus, Tindaro Bongiovanni, Sara Corbu, Vincenzo C Francavilla, Angelica Dessí, Antonio Noto, Giovanni Corsello, Gabriele Finco, Vassilios Fanos, Flaminia C Marincola
Summary: Sportomics is the application of metabolomics to study the metabolism shifts of individuals that practice sports or do physical exercise. This aim is reached by the analysis of low molecular weight metabolites (< 1.5 kDa) present in biological fluids such as blood, saliva or urine. In this study, authors performed a 1H-NMR analysis of urine from 21 professional soccer players collected at 3 different time points during the pre-season preparation period before the beginning of Serie A Championship (First Division) in Italy. Urine profile changed during the observational period. In particular, significant variations were observed for trimethylamine-N-oxide, dimethylamine, hippuric acid, hypoxantine, guanidoacetic acid, 3-hydroxybutyric acid, citric acid and creatine. These modifications could be related to the diet, training and microbiota. For instance, trimethylamine-N-oxide and hippuric acid are both of dietary origins but are also related to the microbiota, while 3-hydroxy-butyric acid is associated with the type of physical exercise. This is the first sportomics study ever performed on professional soccer players, according to authors' knowledge. In the future, sportomics could be applied in a tailored way to choose the best diet and training program in the single individual to obtain the best possible performances and to prevent injuries of athletes.
#9 Incidence of injuries in young soccer players: epidemiological study in an Italian elite club
Reference: J Sports Med Phys Fitness. 2020 Sep 16. doi: 10.23736/S0022-4707.20.11157-5. Online ahead of print.
Authors: Gabriele Thiebat, Andrea Spreafico, Stefano Mazzoni, Giovanni Ravasio, Laura De Girolamo, Herbert Schoenhuber
Summary: Football is the most popular sport in the world, increasingly played by the youngsters. However, little epidemiological data exists regarding injuries in young players. The aim of this study was to describe the most common types and sites of injury among the different classes of a single professional football club. The present perspective study covered a three-season period, including 679 children divided in 9 age classes. All the athletes were managed by the same staff and for each injury, onset date, date of return to training, anatomic site and type of injury were recorded. The mean age of the population was 12.7 years old (Range 7.4- 16.9). A total 975 injuries were recorded without significant differences among seasons (p=0.682). The most affected classes were U17 and U16, while the lowest rate of injury was in U11. The most common injury in U9 and U10 affected foot & ankle, while in all the other classes thigh was the most frequently site involved. Focusing on the type of injury, the most common cause was traumatic (40.9%), followed by muscular diseases. The mean value of absence from soccer was 19.7 days (± 1.2). The highest rate of injuries occurred in September and August. In January and February, injuries were more frequent during competitions, whereas in the other months the rate was inverted. This study highlights that pre-season and the final phase of the season are more at risk of injury and the type of injury differs between classes.
#10 Morphology of possible regions in elite soccer players
Reference: Sports Biomech. 2020 Sep 16;1-14. doi: 10.1080/14763141.2020.1797862. Online ahead of print.
Authors: Nikolas Sten Knudsen, Thomas Bull Andersen
Summary: The popularity of spatio-temporal analyses in soccer is increasing. As many of these analyses depend on the regions a player can occupy in a certain amount of time (the possible regions), the understanding of this concepts is important for analyses to produce usable results. This study investigated how possible regions of soccer morph with varying times and running speeds. Twenty-four players from the Danish Superliga participated, and 13 players were analysed. The possible regions were analysed with times from 0.5 to 4 s (0.5 s increments) and initial velocities from 1 to 7 m/s (1 m/s increments). In this study, we showed that the possible regions can be described by ellipses (eccentricity of 0.5348 ± 0.1912). When comparing the possible region ellipses at every time and velocity pair, 1.95 % of the ellipses were not significantly different from the others. In conclusion, possible regions are unique in shape and size depending on player running speed and time available. However, as only few strikers participated, the results for this group should be interpreted with caution. Coaches can predict possible regions based on these parameters increasing precision of post-game analyses.
#11 Developmental differences of kinematic and muscular activation patterns in instep soccer kick
Reference: Sports Biomech. 2020 Sep 15;1-16. doi: 10.1080/14763141.2020.1815827. Online ahead of print.
Authors: Ali Onur Cerrah, Deniz Şimsek, Abdullah Ruhi Soylu, Hiroyuki Nunome, Hayri Ertan
Summary: Kinematic and neuromuscular activity differences amongst soccer players in different age groups were examined in this study. Thirty male soccer players evenly divided into three age groups (Group 1: age 12-13; Group 2: age 14-15; Group 3: age 16-17) were asked to perform instep kicks towards a target 11 m away. Their anthropometrics, instep kick kinematics, resultant ball velocities, both legs isokinetic strength, and electromyography (EMG) during kicking were compared amongst the three age groups. There were significant differences in height, body mass, body mass index, ball velocities, and isokinetic strength values amongst three age groups. Also, kicking kinematics including angular and linear velocities of hip, knee, ankle, and toe were significantly different (p < 0.05) amongst groups in several kicking phases. Furthermore, the activities of m. rectus femoris, m. vastus medialis, m. biceps femoris were significantly different amongst groups (p < 0.05). The ball velocities and leg strength parameters increased with age, neuromuscular activations, and kinematic parameters differed especially in leg-coking and forward swing phase of instep soccer kick. It should be concluded that an increase of resultant ball velocity of the instep kick is closely associated with chronical age, the development of leg muscle strength, and the neuromuscular activity of the kicking leg.
#12 Body Water Content and Morphological Characteristics Modify Bioimpedance Vector Patterns in Volleyball, Soccer, and Rugby Players
Reference: Int J Environ Res Public Health. 2020 Sep 10;17(18):E6604. doi: 10.3390/ijerph17186604.
Authors: Francesco Campa, Analiza M Silva, Catarina N Matias, Cristina P Monteiro, Antonio Paoli, João Pedro Nunes, Jacopo Talluri, Henry Lukaski, Stefania Toselli
Download link: https://www.mdpi.com/1660-4601/17/18/6604/pdf
Summary: Bioimpedance vector analysis (BIVA) is a widely used method based on the interpretation of raw bioimpedance parameters to evaluate body composition and cellular health in athletes. However, several variables contribute to influencing BIVA patterns by militating against an optimal interpretation of the data. This study aims to explore the association of morphological characteristics with bioelectrical properties in volleyball, soccer, and rugby players. 164 athletes belonging to professional teams (age 26.2 ± 4.4 yrs; body mass index (BMI) 25.4 ± 2.4 kg/m2) underwent bioimpedance and anthropometric measurements. Bioelectric resistance (R) and reactance (Xc) were standardized for the athlete's height and used to plot the vector in the R-Xc graph according to the BIVA approach. Total body water (TBW), phase angle (PhA), and somatotype were determined from bioelectrical and anthropometric data. No significant difference (p > 0.05) for age and for age at the start of competition among the athletes was found. Athletes divided into groups of TBW limited by quartiles showed significant differences in the mean vector position in the R-Xc graph (p < 0.001), where a higher content of body fluids resulted in a shorter vector and lower positioning in the graph. Furthermore, six categories of somatotypes were identified, and the results of bivariate and partial correlation analysis highlighted a direct association between PhA and mesomorphy (r = 0.401, p < 0.001) while showing an inverse correlation with ectomorphy (r = -0.416, p < 0.001), even adjusted for age. On the contrary, no association was observed between PhA and endomorphy (r = 0.100, p = 0.471). Body fluid content affects the vector length in the R-Xc graph. In addition, the lateral displacement of the vector, which determines the PhA, can be modified by the morphological characteristics of the athlete. In particular, higher PhA values are observed in subjects with a high mesomorphic component, whereas lower values are found when ectomorphy is dominant.
The aim of this study was to examine the performance indicators that differentiated between African and European teams in the 2018 FIFA World Cup
The aim of this study was to analyze in-game match statistics on the top-3 and bottom-3 teams ranked in LaLiga.
Following studies were retrieved for this week:
#1 Dose-Response Relationship Between External Load and Wellness in Elite Women's Soccer Matches: Do Customized Velocity Thresholds Add
Reference: Int J Sports Physiol Perform. 2020 Sep 4;1-7. doi: 10.1123/ijspp.2019-0660. Online ahead of print.
Authors: Dawn Scott, Dean Norris, Ric Lovell
Summary: The purpose was to examine the dose-response relationship between match-play high-speed running (HSR), very high-speed running (VHSR), and sprint (SPR) distances versus subsequent ratings of fatigue and soreness. Thirty-six outfield players competing in the professional National Women's Soccer League (NWSL, United States) with a minimum of five 90-minute match observations were monitored during the 2016 and 2017 seasons (408 match observations, 11 /player). HSR (≥3.47 m·s-1), VHSR (≥5.28 m·s-1), and SPR (≥6.25 m·s-1) were determined generically (GEN) in players using a 10-Hz global positioning system. HSR, VHSR, and SPR speed thresholds were also reconfigured according to player peak speed per se and in combination with the final velocity achieved in the 30:15 Intermittent Fitness Test (locomotor approach to establishing individual speed zones). On the morning following matches (match day [MD + 1]), players recorded subjective wellness ratings of fatigue and soreness using 7-point Likert scales. Fatigue (-2.32; 95% CI, -2.60 to -2.03 au; P < .0001) and soreness (-2.05; 95% CI, -2.29 to -1.81; P < .0001) ratings worsened on MD + 1. Standardized unit changes in HSRGEN (fatigue: -0.05; 95% CI, -0.11 to 0.02 and soreness: -0.02, 95% CI, -0.07 to 0.04) and VHSRGEN (fatigue: -0.06; 95% CI, -0.12 to 0.00 and soreness: -0.04; 95% CI, -0.10 to 0.02) had no influence on wellness ratings at MD + 1. Individualized speed thresholds did not improve the model fit. Subjective ratings of fatigue and wellness are not sensitive to substantial within-player changes in match physical performance. HSR, VHSR, and SPR thresholds customized for individual players' athletic qualities did not improve the dose-response relationship between external load and wellness ratings.
#2 The use of recovery strategies by Spanish first division soccer teams: a cross-sectional survey
Reference: Phys Sportsmed. 2020 Sep 3. doi: 10.1080/00913847.2020.1819150. Online ahead of print.
Authors: Albert Altarriba-Bartes, Javier Peña, Jordi Vicens-Bordas, Martí Casals, Xavier Peirau, Julio Calleja-González
Summary: Different active and passive post-exercise recovery techniques such as massage, foam rolling, stretching or ice baths among others, are used by elite athletes to promote effective physiological, physical, and mental restoration. However, limited research is available investigating the use of recovery strategies in professional soccer. As such, we aimed to explore and describe the use of strategies by professional teams throughout the season, describing competitive and preparatory phases. The present study collected data from all professional Spanish soccer teams who played in "LaLiga" (The Spanish first division), during the season 2018-2019 (n=20) and the ones promoted for the season 2019-2020 (n=3). A six-section online survey was responded once. Teams used different recovery protocols and combinations, although natural and physical strategies such as sleep/nap, food/fluid replacement, cold/ice bath/shower/immersion, and massage were always present. However, there is no agreement in the protocols and timings employed. Three physical strategies showed a higher presence in the recovery protocols after competition: cold/ice bath/shower/immersion, massage and foam rolling; always used by seventeen teams (74%), sixteen (70%) and thirteen (57%) respectively. The design and supervision of recovery are multidisciplinary tasks in 87% of the teams. Our findings also demonstrate that although there is a body of scientific evidence on recovery, a gap between theory and practice exists with 13% of the teams acknowledging that insufficient logistics and economic resources limit the use of some strategies, and two teams (9%) not periodizing or individualizing recovery. The investigation provided insight into the current use of recovery strategies by "LaLiga" teams, highlighting that all clubs used them to one extent or another, but also that significant variability responding to individualized perceptions exists. Moreover, this study provides relevant contextual information that may be useful for professional soccer staff concerning the use of recovery strategies.
#3 Differences in GPS variables according to playing formations and playing positions in U19 male soccer players
Reference: Res Sports Med. 2020 Sep 3;1-15. doi: 10.1080/15438627.2020.1815201. Online ahead of print.
Authors: Stefano Borghi, Davide Colombo, Antonio La Torre, Giuseppe Banfi, Matteo Bonato, Jacopo Antonino Vitale
Summary: The aims of this study were 1) to investigate Global Positioning System (GPS)-based match physical performance according to players' playing position in three different playing formations (4-4-2, 3-5-2, 4-3-3) and 2) to analyse the differences in match performance between 1st and 2nd half. Twenty-three U19 elite male soccer players (age: 18 ± 1 year, height: 1.80 ± 0.04 m, body mass: 70.65 ± 6.02 kg), categorized as Central Back (CB, n = 5), Full Back (FB, n = 4), Central Midfielders (CM, n = 4), Wingers (W, n = 3), Strikers (S, n = 7), were monitored using 10 Hz GPS during 31 competitive matches. The results showed that FB and W always had the highest very high-speed running distance and number of sprints in all playing formations. Significant decrease in all GPS variables was observed in the 2nd half of the match for all playing positions. Strength coaches should adopt specific training regimes in accordance with players' playing position.
#4 Using Optical Tracking System Data to Measure Team Synergic Behavior: Synchronization of Player-Ball-Goal Angles in a Football Match
Reference: Sensors (Basel). 2020 Sep 3;20(17):E4990. doi: 10.3390/s20174990.
Authors: Daniel Carrilho, Micael Santos Couceiro, João Brito, Pedro Figueiredo, Rui J Lopes, Duarte Araújo
Download link: https://www.mdpi.com/1424-8220/20/17/4990/pdf
Summary: The ecological dynamics approach to interpersonal relationships provides theoretical support to the use of kinematic data, obtained with sensor-based systems, in which players of a team are linked mainly by information from the performance environment. Our goal was to capture the properties of synergic behavior in football, using spatiotemporal data from one match of the 2018 FIFA WORLD CUP RUSSIA, to explore the application of player-ball-goal angles in cluster phase analysis. Linear mixed effects models were used to test the statistical significance of different effects, such as: team, half(-time), role and pitch zones. Results showed that the cluster phase values (synchronization) for the home team, had a 3.812×10-2±0.536×10-2 increase with respect to the away team (X2(41)=259.8, p<0.001) and that changing the role from with ball to without ball increased synchronization by 16.715×10-2±0.283×10-2 (X2(41)=12227.0, p<0.001). The interaction between effects was also significant. The player-team relative phase, the player-ball-goal angles relative frequency and the team configurations, showed that variations of synchronization might indicate critical performance changes (ball possession changes, goals scored, etc.). This study captured the ongoing player-environment link and the properties of team synergic behavior, supporting the use of sensor-based data computations in the development of relevant indicators for tactical analysis in sports.
#5 Football and COVID-19 risk: correlation is not causation
Reference: Clin Microbiol Infect. 2020 Sep 3;S1198-743X(20)30517-6. doi: 10.1016/j.cmi.2020.08.034. Online ahead of print.
Authors: Fares Ayoub, Toshiro Sato, Atsushi Sakuraba
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7470813/pdf/main.pdf
#6 Strength Conditioning Program to Prevent Adductor Muscle Strains in Football: Does it Really Help Professional Football Players?
Reference: Int J Environ Res Public Health. 2020 Sep 2;17(17):E6408. doi: 10.3390/ijerph17176408.
Authors: Javier F Núñez, Ismael Fernandez, Alberto Torres, Sergio García, Pablo Manzanet, Pascual Casani, Luis Suarez-Arrones
Download link: https://www.mdpi.com/1660-4601/17/17/6408/pdf
Summary: Coaches at the professional level are often concerned about negative side effects from testing and intensive resistance training periods, and they are not willing to base their training prescriptions on data obtained from semiprofessional or amateur football players. Consequently, the purpose of this study was to analyze the reliability and effectiveness of two adductor injury active prevention programs using the adductor/abductor ratio and deficit between legs, on the basis of adduction-abduction power output during the exercises proposed, in professional football players. Forty-eight professional football players undertook complementary strength training for the adductor and abductor muscles in their dominant and non-dominant legs, once or twice a week throughout the playing season. The volume of the session was determined by the adductor/abductor ratio and the deficit between legs in the last session training measured. The number and severity of muscle injuries per 1000 h of exposure were recorded. Both prevention programs showed a very low rate of adductor injury (0.27 and 0.07 injuries/1000 h) with mild-to-moderate severity, maintaining a balance in percentage asymmetry between dominant and non-dominant legs for adductor (10.37%) and in the adductor/abductor ratio (0.92) in top professional football players throughout the season. The strength conditioning program proposed can help to prevent adductor muscle injuries in top professional football players.
#7 An Investigation into the Relationship Between Heart Rate Recovery in Small-Sided Games and Endurance Performance in Male, Semi-professional Soccer Players
Reference: Sports Med Open. 2020 Sep 10;6(1):43. doi: 10.1186/s40798-020-00273-8.
Authors: Lars Reinhardt, Stephan Schulze, Eduard Kurz, René Schwesig
Summary: The ability to recover in the shortest possible time plays an important role especially in intermittent sports such as soccer. Evidence suggests that a well-developed endurance performance has positive effects on the repeated-sprint ability and thus also on the short-term recovery. However, it has not been clarified whether these relationships still exist in a soccer-specific situation. Therefore, the purpose of this investigation was to evaluate the ability of semi-professional soccer players to recover during standardized small-sided games (SSGs) as an endurance performance indicator. Eighteen male semi-professional soccer players (age, 23.5 ± 3.7 years) performed an incremental treadmill test (ITT) to determine their running velocity and heart rate at a fixed lactate threshold of 4 mmol L-1 (v4). Two days later, the players carried out six bouts of 4 vs. 4 SSGs (duration, 90 s; load to rest ratio, 1:1). A GPS-based tracking system was used to determine distances covered at four fixed speed zones (i.e., < 7.2 km/h, 7.2-14.4 km/h, 14.4-19.8 km/h, > 19.8 km/h) and total distance covered during the SSGs. Furthermore, the frequency of occurrence of accelerations (> 1.54 m s-2) was calculated. SSGs' internal load was quantified by average heart rate and blood lactate concentration after the SSGs. Their recovery ability was evaluated using heart rate recovery (HRR) after the last bout of the SSGs. A very large correlation (r = - .91) with an explained variance of 84% was found between HRR and v4. Further, a better performance in the ITT was also related with a higher number of accelerations executed during SSGs (r = .60). The total distance and distances in predefined speed zones did not show any association to v4. This study showed a strong relationship between HRR after standardized 4 vs. 4 SSGs and the soccer players' endurance performance in a laboratory setting. Thus, besides being associated with endurance capacity, v4 seems sufficient to evaluate the sport-specific ability to recover in soccer players.
#8 Effects of Plyometric Jump Training on Jump and Sprint Performance in Young Male Soccer Players: A Systematic Review and Meta-analysis
Reference: Sports Med. 2020 Sep 11. doi: 10.1007/s40279-020-01337-1. Online ahead of print.
Authors: Rodrigo Ramirez-Campillo, Daniel Castillo, Javier Raya-González, Jason Moran, Eduardo Sáez de Villarreal, Rhodri S Lloyd
Summary: Even from a young age, modern soccer requires high levels of physical fitness development, particularly jumping and sprinting. Plyometric jump training (PJT), combined with young athletes' regular soccer sessions, has the potential to improve jumping and sprinting. However, studies exploring the effects of PJT are generally limited by small sample sizes. This problem of underpowered studies may, thus, be resolved by pooling study results in a meta-analysis. The objective of this systematic review with meta-analysis (SRMA) was to assess the effects of plyometric jump training (PJT) on jumping and sprinting among young male soccer players. The SRMA included peer-reviewed articles that incorporated PJT in healthy players (i.e., < 23 years of age), a control group, and a measure of jumping or sprinting. Means and standard deviations of outcomes were converted to Hedges' g effect sizes (ES), using the inverse variance random-effects model. Moderator analyses were conducted for PJT duration, frequency, total number of sessions, participants' chronological age, and FIFA age categories (i.e., U-17 vs. U-20 vs. U-23). A multivariate random-effects meta-regression was also conducted. Thirty-three studies were included, comprising 1499 participants. PJT improved vertical jump tests (ES = 0.60-0.98; all p < 0.01) and linear sprint performance (ES = 0.60-0.98; p < 0.03). Interventions of > 7 weeks and > 14 PJT sessions induced greater effects compared to PJT with ≤ 7 weeks and ≤ 14 total sessions on 10-m sprint performance (between group p = 0.038). PJT is effective in improving jumping and sprinting performance among young male soccer players. Greater 10-m linear sprinting improvements were noted after interventions > 7-week duration and > 14 sessions, suggesting a greater return from exposure to longer PJT interventions, partially in support for the adoption of a long-term approach to athletic development in young athletes. However, with reference to the findings of the meta-regression, and those from the remaining subgroup and single factors analysis, a robust confirmation regarding the moderator role of participant's age or PJT configuration effects on young soccer player's fitness qualities needed.
#9 Anthropometric and physical performance profiling does not predict professional contracts awarded in an elite Scottish soccer academy over a 10-year period
Reference: Eur J Sport Sci. 2020 Sep 4;1-10. doi: 10.1080/17461391.2020.1808079. Online ahead of print.
Authors: Thomas P Craig, Paul Swinton
Summary: The purpose of this long-term retrospective analysis was to determine whether anthropometric and physical performance data could predict success in elite youth Scottish soccer players. Stature, body mass, sprint, jump and aerobic performance were collected from 512 players (U10 to U17) across a 10-year period. Players participated in an average of four profiling sessions (range: 1-14) and up to a maximum of three per year (August, December, and May) with standardisation applied to the surface, test order, time and protocols. One hundred players were awarded professional contracts. Associations between variables were quantified with mixed-effects linear models. Prediction was assessed with least absolute shrinkage and selection operator (LASSO) regression developed on a training set (2/3 data) and tested with proportion of error on a leave-out (1/3 data) test set. Confidence intervals were obtained through bootstrap LASSO samples. A strong relative age bias was identified with 50% of successful players born in the first quarter of the year. Successful players were on average taller and performed better in sprint and jump tests (p < 0.05). However, effects were small and even when variables were combined, proportion of errors identified were similar to random guessing (0.45[95%CI:0.41-0.49]). The results indicate that whilst successful players as youths demonstrate on average distinct anthropometric and physical profiles, these differences are unlikely to provide a reliable source to predict success within an already talented group. Practitioners should use data collected to guide exercise prescription but be aware of its substantive limitations in predicting success in isolation. Using robust statistical procedures, researchers and practitioners within soccer academies that are continually collecting data should assess whether accurate predictions can be made combining data across a holistic range of dimensions including physiological, technical, psychological, tactical skills and expertise from technical coaches. Academies should consider processes such as coach and scout education programmes to reduce the negative impacts of controllable factors such as the RAE. There are limitations of using anthropometric and physical performance profiling data to predict who will become a successful player. The information is still an important part of the talent development process with data being used to assist the creation and individual tailoring of physical training and appropriate recording and monitoring is encouraged.
#10 Injury Analysis in Professional Soccer by Means of Media Reports - Only Severe Injury Types Show High Validity
Reference: Open Access J Sports Med. 2020 Aug 7;11:123-131. doi: 10.2147/OAJSM.S251081. eCollection 2020.
Authors: Volker Krutsch, Stephan Grechenig, Oliver Loose, Leonard Achenbach, Johannes Zellner, Heiko Striegel, Volker Alt, Johannes Weber, Markus Braun, Stephan Gerling, Werner Krutsch
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7431944/pdf/oajsm-11-123.pdf
Summary: Injury data of professional soccer players obtained from media reports are frequently used in scientific research, but the accuracy of such data is still unclear. Injuries of professional soccer players of the German first and second league were documented by continuously screening media reports over one season (2015-2016). After the season, the validity of media-reported injuries was anonymously analyzed by the team physicians of 8 different soccer clubs. A total of 255 injuries of 240 players of 8 professional soccer teams had been published online, of which 146 were confirmed by the team doctors as correct, yielding a rate of 57.3% of confirmed media-reported injuries. In addition, 92 injuries without media registration were detected and added to the online statistics, resulting in 347 injuries and an overall weak validity of media-based data of 42.1%. Statistical analysis showed that the validity of media-reported injury data depended on both the individual soccer club and the body site affected by injury: publications on knee injuries (78.2%) had a higher validity than those on foot injuries (46.2%), and publications on severe injuries had a higher validity (joint dislocation: 100%; ligament rupture: 82.9%; fracture: 73.3%) than those on minor injuries. Publications on specific severe soccer injuries, such as anterior cruciate ligament (ACL) injuries, had a validity of 100%. Media-based injury data were only valid for a few severe injury types such as ACL injuries. In daily soccer routine and scientific research, media-based data should thus only be used in combination with specific criteria or verification processes.
#11 Comparison of symptomatic spondylolysis in young soccer and baseball players
Reference: J Orthop Surg Res. 2020 Sep 3;15(1):378. doi: 10.1186/s13018-020-01910-4.
Authors: Takuji Yokoe, Takuya Tajima, Hiroshi Sugimura, Shinichirou Kubo, Shotarou Nozaki, Nami Yamaguchi, Yudai Morita, Etsuo Chosa
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7469272/pdf/13018_2020_Article_1910.pdf
Summary: Spondylolysis is the main cause of low back pain (LBP) in young athletes. There are few studies analyzing the difference of spondylolysis among young athletes with different sports activities. The purpose of this study was to compare the clinical factors and distribution of the lesions of spondylolysis on magnetic resonance imaging (MRI) scans in young soccer and baseball players with symptomatic spondylolysis. The medical records of 267 young athletes aged 7 to 18 years old who underwent MRI to evaluate the cause of LBP between 2017 and 2020 were retrospectively reviewed to identify patients with spondylolysis. Of the young athletes with symptomatic spondylolysis, clinical factors and MRI findings in soccer and baseball players were retrospectively evaluated. The clinical factors were age, sex, interval from onset of LBP to MRI, and side of the dominant leg in the sports field. MRI findings included number, lumbar level, and side of the lesions. A total of 33 soccer players (mean age, 15.4 ± 1.4 years) and 49 baseball players (mean age, 15.4 ± 1.6 years) with symptomatic spondylolysis were enrolled. All patients were male. No significant differences were noted in age and the interval from onset of LBP to MRI between the groups. Soccer players had greater numbers of multiple (p < 0.001) and bilateral (p < 0.001) lesions than baseball players. The dominant side of the hand for pitching or batting was correlated with the contralateral-side lesions in baseball players (p = 0.001). The distribution of the lesions of spondylolysis differed in young soccer and baseball players. Pitching or batting with the dominant-side hand would be associated with contralateral-side lesions in baseball players. Sports-specific movements and the side of the dominant leg should be considered when treating young athletes with symptomatic spondylolysis.
#12 Heading in the right direction: A critical review of studies examining the effects of heading in soccer players
Reference: J Neurotrauma. 2020 Sep 3. doi: 10.1089/neu.2020.7130. Online ahead of print.
Authors: Taylor Snowden, Hannah Reid, Samantha Kennedy, Rebecca A Kenny, Amanda McQuarrie, Lynneth Stuart-Hill, Mauricio Garcia-Barrera, Jodie Gawryluk, Brian Ross Christie
Summary: The practice of heading in soccer has become a public concern due to the potential for subconcussive impacts to cause cumulative concussive-like effects; however experimental evidence for this hypothesis has been mixed. This systematic review used pre-defined search parameters to assess primary literature that examined changes in cognitive, behavioural, structural and/or biological processes after acute heading exposure in youth and young adult soccer players. The findings were synthesized into a concise and comprehensive summary of the research following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) format, and suggestions for standardization of acute heading protocols are described. A total of 1189 articles were considered for this review, with 19 articles meeting all of the inclusion criteria for full analysis. An attempt was made to identify methods with significant sensitivity and reliability by grouping studies based on their outcome measures. Due to lack of standardization across intervention types and data collection protocols, no sensitive and reliable methods could be conclusively identified to assess the effects of acute heading exposure in soccer players. Based on this review, there is not enough evidence to either support or refute the potential of effects of subconcussive events from acute soccer heading exposure. Recommendations for standardization of acute heading exposure studies based on the included literature are discussed. Standardization is required to better understand the impact of acute heading exposure in soccer players, while allowing for the development of guidelines that mitigate any potential risks and allowing athletes to remain active and develop their skills.
The aim was to examine strategic time-wasting, a behavior that help teams win games or tie games against superior opponents.
The aim was to investigate the association between injuries and training load indices in elite footballers.
Following studies were retrieved for this week:
#1 The Immediate Effect of Spinal Manipulation on Ball Velocity and Neuromuscular Function During an Instep Kick in Former Varsity Soccer
Players: A Feasibility Study
Reference: J Strength Cond Res. 2020 Aug 18. doi: 10.1519/JSC.0000000000003720. Online ahead of print.
Authors: Melissa Corso, Carmen Liang, Steve Tran, Scott Howitt, John Srbely, Silvano A Mior
Summary: Spinal manipulation (SM) has been shown to increase ball velocity (BV) in soccer players. Evidence suggests that SM modulates responses at spinal or cortical levels to enhance force production in asymptomatic populations. No studies have explored the underlying neuromuscular mechanisms contributing to changes in BV post-SM in soccer players. We assessed the feasibility of measuring change in BV and neuromuscular function after SM in former Varsity level soccer players with a pre-post study design. Three to 5 maximal instep kicks were performed before and after SM at the L3-5 level. Ball velocity was measured using high-speed camera. Activation of lower limb and trunk musculature was recorded with electromyography. Outcomes included ease of recruitment, scheduling and data capture, as well as expectation and perception of SM effect and adverse events (AE). Fifteen potential subjects were recruited over 1.5 months. Eleven were scheduled (24-31 years; 8 females, 3 males). Two subjects reported mild AE after maximal voluntary isometric contraction testing. A significant increase in BV (mean change: 1.75 m·s [95% confidence interval: 0.5-3.0]) and a trend to increased peak-activation of knee extensors (90.7%) were observed post-SM. Findings suggest that our recruitment strategy and methodology are feasible in a larger trial with some modifications. Our preliminary findings support previous research by suggesting that increased BV may be mediated through increased activation of knee extensors during the kick. Our findings may offer additional insight into the underlying neuromuscular mechanisms contributing to immediate change in BV post-SM.
#2 Importance of anthropometric features to predict physical performance in elite youth soccer: a machine learning approach
Reference: Res Sports Med. 2020 Aug 23;1-12. doi: 10.1080/15438627.2020.1809410. Online ahead of print.
Authors: Tindaro Bongiovanni, Athos Trecroci, Luca Cavaggioni, Alessio Rossi, Enrico Perri, Giulio Pasta, F Marcello Iaia, Giampietro Alberti
Summary: The present study aimed to determine the contribution of soccer players' anthropometric features to predict their physical performance. Sixteen players, from a professional youth soccer academy, were recruited. Several anthropometric features such as corrected arm muscle area (AMAcorr), arm muscle circumference (AMC) and right and left suprapatellar girths (RSPG and LSPG) were employed in this study. Players' physical performance was assessed by the change of direction (COD), sprint (10-m and 20-m), and vertical jump (CMJ) tests, and Yo-Yo Intermittent Recovery Test level 1 (Yo-Yo IRT1). Using an extra tree regression (ETR) model, the anthropometric features permitted to accurately predict 10-m sprint, 20-m sprint and Yo-Yo IRTL 1 performance (p < 0.05). ETR showed that upper-body features as AMAcorr, and AMC affected 10-m and 20-m sprint performances, while lower-body features as RSPG and LSPG influenced the Yo-Yo IRTL 1 (Overall Gini importance ≥ 0.22). The model predicting COD and CMJ presented a poor level of prediction, suggesting that other factors, rather than anthropometric features, may concur to predict their changes in performance. These findings demonstrated that the upper- and lower-body anthropometric features are strictly related to sprint and aerobic fitness performance in elite youth soccer.
#3 Injuries according to the percentage of adult height in an elite soccer academy
Reference: J Sci Med Sport. 2020 Aug 11;S1440-2440(20)30736-2. doi: 10.1016/j.jsams.2020.08.004. Online ahead of print.
Authors: X Monasterio, S M Gil, I Bidaurrazaga-Letona, J A Lekue, J Santisteban, G Diaz-Beitia, I Martin-Garetxana, E Bikandi, J Larruskain
Summary: This study aimed to ascertain if there is a defined pattern of injury related to the percentage of attained adult height and classify injuries according to maturity status bands. From 1998-2019, 63 elite male soccer players of at least the U12 category from a Spanish LaLiga club's academy were followed until reaching their final height. Medical staff recorded injuries following the FIFA consensus and measured height 2-3 times per season. The percentage of adult height at which each injury occurred was calculated using the player's closest height to the injury and his final adult height. Injuries were classified in maturity bands, pre-peak-height-velocity (PHV) <88%, circa-PHV 88%-96%, and post-PHV >96%. There were 509 injuries among the 63 players. Growth-related injuries occurred at a median (IQR) of 91.2% (86.7%-95.2%) of adult height, predominating in pre-PHV and PHV bands. Muscle injuries predominantly occurred at post-PHV, with 77.78% of those conditions occurring within that time frame and at 98.7% (96%-99.5%) of adult height. Likewise, knee and ankle joint/ligament injuries predominated at post-PHV (87% and 65% of total cases, respectively) occurring at 99.0% (97.9%-99.9%) and 98.4% (89.2%-99.4%) of adult height, respectively. Injuries follow a specific pattern according to the percentage of adult height.
#4 Predicting Maximal Lactate Steady State from Carminatti's Shuttle Run Test in Soccer Players
Reference: Int J Sports Med. 2020 Aug 25. doi: 10.1055/a-1224-3985. Online ahead of print.
Authors: Lorival José Carminatti, Bruna Nunes Batista, Juliano Fernandes da Silva, Artur Ferreira Tramontin, Vitor Pereira Costa, Ricardo Dantas de Lucas, Fernando Klitzke Borszcz
Summary: The objective of the present study was to determine the validity of Carminatti's shuttle run incremental test-T-Car derived parameters in estimating the maximal lactate steady state determined in shuttle run format. Eighteen soccer players performed a T-Car test, and several trials to determine the maximal lactate steady state. From T-Car were derived the heart rate deflection point, peak speed, maximal heart rate and parameters resulting from percentage of peak measures. The validity was accessed by Bland-Altman plots, linear regressions, and two one-sided tests of equivalence analysis. The results showed the speed at 80.4% of T-Car peak speed, the heart rate deflection point and the 91.4% of maximal heart rate were equivalent to maximal lactate steady state (Mean difference; ±90% compatibility interval; -0.8; ±1.5%, -0.4; ±1.1%, and 0.0; ±2.7%, respectively). Additionally, peak speed during the T-Car test was a stronger predictor of maximal lactate steady state (MLSS [km/h]=2.57+0.65 × sPeak; r=0.82 [90% CI; 0.62-0.92], standard error of the estimate=3.6%; 90% CI ×/÷1.4). Therefore, soccer players can use the T-Car derived parameters as a noninvasive and practical alternative to estimate the specific maximal lactate steady state for soccer.
#5 Relationships between Linear Sprint, Lower-Body Power Output and Change of Direction Performance in Elite Soccer Players
Reference: Int J Environ Res Public Health. 2020 Aug 22;17(17):E6119. doi: 10.3390/ijerph17176119.
Authors: Monika Papla, Michal Krzysztofik, Grzegorz Wojdala, Robert Roczniok, Marcin Oslizlo, Artur Golas
Download link: https://www.mdpi.com/1660-4601/17/17/6119/pdf
Summary: The aim of this study was to investigate the relationship between linear sprint, power output obtained during a squat and change of direction (COD) performance. Fifteen elite soccer players participated in this study (age = 21.7 ± 0.72 years, body mass = 74.9 ± 9.11 kg, body height = 180.4 ± 7 cm, training experience = 9 ± 1.5 years). To examine these correlations a following battery of tests were carried out: 20-m linear sprint, one-repetition maximum (1RM) squat strength, peak power output obtained during a squat at 50% 1RM and time obtained in two 20-m COD tests with different angles of direction change (90° and 135°). In addition, COD deficits (90°-CODDEF and 135°-CODDEF) for both COD tests were calculated. The Spearman's rank order correlation showed a nearly perfect statistical relationship between the 90°-COD and the 90°-CODDEF (r = 0.9; p < 0.001). In the case of 90°-CODDEF, there was a large statistical relationship with 135°-CODDEF (r = 0.59; p = 0.021). Moreover, there was a nearly perfect statistical relationship between 135°-COD and 135°-CODDEF (r = 0.91; p < 0.001). The statistically insignificant (p > 0.05) relationship between 20-m linear sprint time, power output obtained during a squat at 50% 1RM, 1RM squat strength level and both COD test, as well as both COD deficits were found. Results of the present study showed that 20-m linear sprinting speed, 1RM squat strength, power output obtained during squat at 50% 1RM and COD ability at 90° and 135° angles, are separate physical qualities. Moreover, it seems that COD deficit provides a more isolated measure of COD ability than the COD tests alone and does not must be limited to a specific angle, but provides knowledge about the COD ability in a range of other angles, at least concerning 90° and 135° COD angles.
#6 Nine typical injury patterns in German professional male football (soccer): a systematic visual video analysis of 345 match injuries
Reference: Br J Sports Med. 2020 Aug 26;bjsports-2019-101344. doi: 10.1136/bjsports-2019-101344. Online ahead of print.
Authors: Christian Klein, Patrick Luig, Thomas Henke , Hendrik Bloch, Petra Platen
Summary: We aimed to systematically analyse the videos of acute injuries in professional men's football and describe typical injury patterns. Injuries were registered with the German statutory accident insurance for professional athletes as part of occupational accident reporting. Following each season (2014-2017), video footage of the two highest divisions in German male football was searched for moderate and severe acute match injuries. Two raters then independently assessed the injuries for: game situation, player and opponent behaviour, referee decision, and injury mechanisms. The total data set included 7493 acute injuries. Of these, 857 (11%) were moderate or severe match injuries. The video search yielded 345 (40%) clearly identifiable injuries and of those 170 (49%) were contact injuries. We describe nine typical injury patterns: one each for head and shoulder injuries, two for thigh and ankle, and three for knee injuries. The nine patterns are called: (1) Head-to-head injury. (2) Collision-and-fall shoulder injury. (3) Sprinter's thigh injury. (4) Perturbation-and-strain thigh injury. (5) Tackle knee injury. (6) Tackle-and-twist knee injury. (7) Non-contact knee injury. (8) Attacked ankle injury. (9) Collision-and-twist ankle injury. Thigh injuries occurred primarily in non-contact situations (44/81), mostly while the player was sprinting (23/44). Knee injuries were often caused by direct external impact (49/84)-mainly suffered by the tackler during a tackle (17/49). The nine common injury patterns in football differed substantially in their mechanisms and causes.
#7 Intra-Individual and Seasonal Variation of Selected Biomarkers for Internal Load Monitoring in U-19 Soccer Players
Reference: Front Physiol. 2020 Aug 4;11:838. doi: 10.3389/fphys.2020.00838. eCollection 2020.
Authors: Manuel Becker , Billy Sperlich 3 , Christoph Zinner 4 , Silvia Achtzehn 5 6
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7417431/pdf/fphys-11-00838.pdf
Summary: The aim of this study was to investigate inter-day and -week as well as intra- and inter-individual variation of selected biomarkers in high-performance youth soccer players to assist practitioners interpreting player's internal load to counteract underperformance and unwanted health risks. Eleven male youth soccer players were tested multiple times during two 3-week periods at midpoint (3-wkmid) and at the end (3-wkend) of the first half of a German under-19 1. Bundesliga season. The levels of creatine kinase (CK), urea, and C-reactive protein (CRP) were measured during 3-wkmid and 3-wkend each Monday, Wednesday, and Friday. In 3-wkmid the CK median was 14% higher (241 vs. 212 U/L) compared to 3-wkend (P = 0.26, ES = 0.16). Overall, the medians of CK, urea (P = 0.59, ES = 0.08), and CRP (P = 0.56, ES = 0.10) during 3-wkmid did not differ to the values of 3-wkend. Daily coefficient of variations (CVs) ranged from 22 to 71% (CK), 17 to 37% (urea), and 9 to 164% (CRP). Individual medians ranged from 101 to 350 U/L (CK), 23 to 50 mg/dL (urea), and 0.6 to 1.1 mg/L (CRP). High intra-individual variability was demonstrated by large intra-individual CVs (medians: CK 50%, urea 18%, and CRP 45%). Our data show (i) large inter-day and inter-week variability of all biomarkers, depending on the external load and (ii) considerable inter- and intra-individual parameter variations. Creatine kinase concentrations could sensitively reflect soccer-specific loads during the season.
#8 TacticUP Video Test for Soccer: Development and Validation
Reference: Front Psychol. 2020 Aug 4;11:1690. doi: 10.3389/fpsyg.2020.01690. eCollection 2020.
Authors: Guilherme Machado, Israel Teoldo da Costa
Download links: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7422863/pdf/fpsyg-11-01690.pdf
Summary: This study aims to expand the process of tactical assessment of soccer players through the development and validation of a video-based test based on core tactical principles of play. The TacticUP video test for soccer is composed of offensive and defensive video sequences of 11vs11 soccer situations. Participants should choose the most appropriate solution for each video sequence. Content validity was established based on a panel of nine experts from four different countries. Construct validity was assessed through the comparison between players with distinct expertise levels. Comparisons between groups' final scores showed statistical differences (p < 0.05) in 10 out of the 15 variables assessed, in which the expert group displayed higher values compared to the non-expert group. Face validity examined the acceptability and suitability of the test by players. Reliability was determined through the test-retest method for each video sequence, and Cohen's Kappa values ranged from 0.622 to 1.0. Therefore, the TacticUP video test showed adequate content, construct, and face validity and was a reliable measure of perceptual-cognitive and decision-making skills in soccer. We overcame limitations from previous video-based tests in soccer by introducing situations concerning off-the-ball movements in both offensive and defensive phases. The practical applications of this test are: (i) it can be used to monitor players' perceptual-cognitive and decision-making skills; (ii) the test is based on players' response selection in a video-based test, which enables the measurement of their perceptual-cognitive and decision-making skills based on the core tactical principles of play; (iii) generate players' tactical profile considering their perceptual-cognitive and decision-making skills based on core tactical principles of play; and (iv) measure the effectiveness of intervention/training programs on the development of perceptual-cognitive and decision-making skills.
#9 On-Field Perceptual-Cognitive Training Improves Peripheral Reaction in Soccer: A Controlled Trial
Reference: Front Psychol. 2020 Aug 7;11:1948. doi: 10.3389/fpsyg.2020.01948. eCollection 2020.
Authors: Nils Schumacher, Rüdiger Reer , Klaus-Michael Braumann
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7427441/pdf/fpsyg-11-01948.pdf
Summary: Abilities such as peripheral reaction are of special importance in soccer. Whether these abilities can be improved by sport-specific on-field interventions remains unclear. The aim of the present controlled trial was to investigate the effect of a soccer-specific perceptual-cognitive on-field training on peripheral reaction of highly talented soccer players aged 12-13 years. N = 38 male elite athletes from young talent centers were allocated to an intervention (n = 19) and a control group (CG) (n = 19). Computer-based peripheral perception tests were conducted before and after intervention. Combining a sport-specific and a juggling task, the intervention was performed once a week (8 weeks, 20 min per week) in addition to team training. The CG exclusively underwent usual team training. Analyses show significant differences between the two groups for peripheral reaction time (PRT), with significant improvements for the intervention group and none for the CG. Furthermore, results indicate that improvements in peripheral reaction might be due to changes in the reaction time of right-footed players. Future studies should be conducted to clarify the effect of sport-specific on-field training approaches on PRT. These analyses should consider the influence of lateralization on effectivity of perceptual-cognitive on-field training approaches.
#10 An Acute Bout of Soccer Heading Subtly Alters Neurovascular Coupling Metrics
Reference: Front Neurol. 2020 Jul 24;11:738. doi: 10.3389/fneur.2020.00738. eCollection 2020.
Authors: Jonathan D Smirl, Dakota Peacock, Alexander D Wright, Kevin J Bouliane , Jill Dierijck, Joel S Burma, Michael Kennefick, Colin Wallace, Paul van Donkelaar
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7396491/pdf/fneur-11-00738.pdf
Summary: The current investigation examined how a bout of soccer heading may impact brain function. We used controlled soccer heading. Seven male soccer players (24.1 ± 1.5 years) participated in this study. 40 successful soccer headers were performed in 20 min (25 m, launch velocity ~80 km/h). X2 xPatch recorded linear and rotational head accelerations during each impact. A contact control "sham" condition - ball made body contact, but not by the head; and a no activity time "control" condition were also completed. Posterior and middle cerebral artery (PCA and MCA, respectively), cerebral blood velocity (CBV) was recorded during a visual task (neurovascular coupling: NVC) alongside SCAT3 symptoms scores pre/post a controlled bout of soccer heading. Cumulative linear and rotational accelerations were 1,574 ± 97.9 g and 313,761 ± 23,966 rads/s2, respectively, during heading and changes in SCAT3 symptom number (pre: 2.6 ± 3.0; post: 6.7 ± 6.2, p = 0.13) and severity (pre: 3.7 ± 3.6, post: 9.4 ± 7.6, p = 0.11) were unchanged. In the PCA, no NVC differences were observed, including: relative CBV increase (28.0 ± 7.6%, p = 0.71) and total activation (188.7 ± 68.1 cm, p = 0.93). However, MCA-derived NVC metrics were blunted following heading, demonstrating decreased relative CBV increase (7.8 ± 3.1%, p = 0.03) and decreased total activation (26.7 ± 45.3 cm, p = 0.04). Although an acute bout of soccer heading did not result in an increase of concussion-like symptoms, there were alterations in NVC responses within the MCA during a visual task. This suggests an acute bout of repetitive soccer heading can alter CBV regulation within the region of the brain associated with the header impacts.
#11 No relationship between the nordic hamstring and two different isometric strength tests to assess hamstring muscle strength in professional soccer players
Reference: Phys Ther Sport. 2020 Aug 18;46:97-103. doi: 10.1016/j.ptsp.2020.08.009. Online ahead of print.
Authors: Víctor Moreno-Pérez, Alberto Méndez-Villanueva, Aitor Soler, Juan Del Coso, Javier Courel-Ibáñez
Summary: The aim was to investigate the relationship between one eccentric and two isometric tests commonly used to assess hamstring strength in professional soccer. Twenty male professional soccer players participated in this study. Hamstring force was quantified during 3 tests (Nordic hamstring eccentric, 90:20 isometric posterior-chain strength and isometric 15° knee flexion) using a load cell, a handheld dynamometer and a force platform, respectively. Poor relationships and low concordance were observed between isometric and eccentric tests, showing different ability to discriminate hamstring weakness and asymmetries. The Nordic hamstring test identified between-limb asymmetry >15% in 30% of the players, 25% in the 15° knee flexion and 5% in the 90:20 test. All players obtained different results in the three tests with only one showing asymmetry >15% in two tests. Results obtained in each test cannot inform the others. Mechanical outputs of these tests must be used for particular purposes during the prevention, rehabilitation and monitoring process of hamstring injury. Isometric testing might be preferable during the initial phases of the recovery process of a hamstring injury while the Nordic hamstring test might be used in the last stages or detect muscle weakness/asymmetries in non-injured players.
#12 Ankle laxity affects ankle kinematics during a side-cutting task in male collegiate soccer athletes without perceived ankle instability
Reference: Phys Ther Sport. 2020 Aug 28;46:89-96. doi: 10.1016/j.ptsp.2020.08.012. Online ahead of print.
Authors: Shun Kunugi, Takashi Koumura, Ryota Myotsuzono, Akihiko Masunari, Naruto Yoshida, Shumpei Miyakawa, Naoki Mukai
Summary: The objective was to investigate whether ankle joint laxity alone influences lower limb kinematics during a side-cutting task. In total, 66 male collegiate soccer players with history of ankle sprains with no perceived ankle instability were categorised into three groups: no-laxity copers (n = 26), laxity copers (n = 23), and severe-laxity copers (n = 17). The hip, knee, ankle, rearfoot, midfoot, and forefoot kinematic data during the stance phase (0%-100% indicated initial contact to take-off) of a 45° side-cutting task were analysed using one-dimensional statistical parametric mapping. The horizontal plane kinematics of the rearfoot differed significantly among the three groups during 30%-91% of the stance phase (P < .05). Severe-laxity copers exhibited a greater external rotation angle than no-laxity copers during 6%-14% and 32%-92% of the stance phase (P < .05). Our data suggest that severe ankle joint laxity affects rearfoot horizontal plane kinematics in individuals without perceived ankle instability performing a 45° side-cutting task. These findings could be used by clinicians in developing rehabilitation programs to prevent further ankle sprains in patients with severe ankle joint laxity.
The study quantified the linear and angular kinematics that result from purposeful heading in youth.
The aim was to investigate the impact of video speed on the decision making process of association football referees and how this interacts with expertise.
Following studies were retrieved for this week:
#1 Small-Sided Games Are Not as Effective as Intermittent Running to Stimulate Aerobic Metabolism in Prepubertal Soccer
Reference: Int J Sports Physiol Perform. 2020 Aug 19;1-7. doi: 10.1123/ijspp.2019-0966. Online ahead of print.
Authors: Anasthase Massamba, Stéphane P Dufour, Fabrice Favret, Thomas J Hureau
Summary: The purpose of this study was to investigate the influence of the soccer pitch area during small-sided games (SSG) in prepubertal children on physiological and technical demands, and to compare them, for the physiological demands, to high-intensity interval training (HIIT). Ten young soccer players (13.0 [0.3] y) performed a HIIT and 3 SSG of various field sizes (30 × 20 m, 42 × 38 m, and 51 × 34 m). Each SSG was performed with 5 players per team, during 4 × 4-minutes interspaced with 1 minute of passive recovery in between. HIIT also followed a 4 × 4-minute protocol with running speed set on an individual basis. Heart rate (HR) was continuously monitored during training sessions. For each exercise modality, time spent above 90% of HRmax (T≥90%,HRmax) was calculated, and technical actions were quantified during SSG by video analysis. T≥90%,HRmax was similar between the 3 SSG (∼587  s; P > .2) but 24% to 37% lower than during HIIT (826  s, P < .05). Coefficients of variations in T≥90%,HRmax were 2.3 to 3.5 times larger in SSG compared with HIIT. For technical actions, greater number of possessions (21  vs ∼14 ), and lower ball touches per possession (2.4 [0.6] vs ∼2.9 [0.6]) were found in the small SSG compared with larger SSG, respectively (P < .05). The 3 SSG led to lower acute stimulation of the aerobic metabolism, suggesting a lower potential for chronic aerobic adaptations, compared with HIIT. Moreover, interindividual variability in the physiological response was substantially greater in SSG compared with HIIT, indicating increased heterogeneity among players performing the same training protocol.
#2 Effects of Combined Strength and Power Training on Physical Performance and Interlimb Asymmetries in Adolescent Female Soccer Players
Reference: Int J Sports Physiol Perform. 2020 Aug 20;1-9. doi: 10.1123/ijspp.2019-0265. Online ahead of print.
Authors: Elena Pardos-Mainer, José Antonio Casajús, Chris Bishop, Oliver Gonzalo-Skok
Summary: The purpose was to examine the effects of an 8-week combined strength and power training intervention on physical performance and interlimb asymmetries in adolescent female soccer players. Thirty-seven adolescent female soccer players (age 16.1 [1.1] y) were randomly assigned to a control group (n = 18) or experimental group (n = 19). The experimental group performed combined strength and power training twice a week, which consisted of strength and power exercises that trained the major muscles of the lower body and trunk musculature. Preintervention and postintervention tests included unilateral and bilateral horizontal and countermovement jump tests, a 40-m sprint test (10- and 30-m split times), a 10-m sprint with a 180° change-of-direction (COD) test, and a multiple-COD test (V-cut test). Asymmetries were also analyzed in the unilateral tests. Significant group-by-time interaction of the improvement between pretest and posttest was observed for speed (effect size [ES]: -1.30 to -1.16) and COD tests (ES: -0.62 to -0.61) but not in jumping (ES: -0.09 to 0.28) and interlimb-asymmetry tests (ES: -0.13 to 0.57). The short-term in-season combined strength and power training program induced greater speed and COD performance improvements than soccer training alone in adolescent female soccer players.
#3 Epidemiology of soccer-related head injury in children 5-14 years in Victoria, Australia
Reference: J Paediatr Child Health. 2020 Aug 20. doi: 10.1111/jpc.15114. Online ahead of print.
Authors: Amy E Smith, Catherine Krejany, Moyez Jiwa
Summary: Our aim was to use epidemiological data to determine the incidence of soccer-related head injuries in children aged 5-14 years who presented at emergency departments (EDs) or were admitted in hospitals in Victoria, Australia. ED presentation and hospital admission de-identified aggregate data were from the Victorian Injury Surveillance Unit. Soccer participation data were compared with the soccer-related head injury data to determine the incidence of this injury among these children. The incidence of ED presentations was 0.17% of children participating in soccer during the study period (financial years 2011-2012 to 2015-2016). The 10-14-years age group presented with more head injuries than the 5-9-years age group. For the admissions data, soccer had a significantly lower (P = 0.0379) incidence of head injury when compared with 'sport as a whole'. The low incidence of soccer-related head injuries presenting to an ED or admission to hospital is consistent with international findings.
#4 External Validity of the T-SAFT90: A Soccer Simulation Including Technical and Jumping Activities
Reference: Int J Sports Physiol Perform. 2020 Aug 18;1-7. doi: 10.1123/ijspp.2019-0057. Online ahead of print.
Authors: Cristiano D da Silva, Ric Lovell
Summary: The purpose was to examine the physiological, muscle-damage, endocrine, and immune responses to a modified soccer-simulation protocol to include technical and jumping activities characteristic of match play (the Technical Soccer-Specific Aerobic Field Test; T-SAFT90). Eighteen university players (age 23  y, stature 175  cm, body mass 74  kg) performed the 90-minute protocol, with acute physiological responses monitored via heart rate, ratings of perceived exertion (6-20 scale), and body mass changes. Creatine kinase, myoglobin, cortisol, and leukocyte subset concentrations were measured at baseline, immediately (0 h), and 24 hours post T-SAFT90. T-SAFT90 incurred an average heart rate equivalent to 87% (5%) of maximum, 16 (2) a.u. ratings of perceived exertion, and a 1.5% (1.0%) body mass deficit. Moderate to large proliferation of leukocyte subsets (P ≤ .01; leukocytes: 6.4-fold; neutrophils: 5.5-fold; lymphocytes: 2.0-fold) and increases in cortisol (2.3-fold) were observed at 0 hours (effect size = 1.13-3.52), each returning to baseline by 24 hours (P > .45; effect size = 0.05-0.50). Myoglobin peaked immediately post T-SAFT90 (4.8-fold), whereas creatine kinase (24 h: 6.0-fold) showed a delayed time course (both P ≤ .001; very large effects; effect size = 2.66 and 3.43, respectively).
Conclusions: The magnitude and time course of the physiological, immune, endocrine, and muscle-damage markers observed during and following T-SAFT90 are similar to values reported in match-play literature, demonstrating external validity of the simulation.
#5 Effects of Integrative Neuromuscular Training on Motor Performance in Prepubertal Soccer Players
Reference: J Strength Cond Res. 2020 Aug 12. doi: 10.1519/JSC.0000000000003666. Online ahead of print.
Authors: Glauber B Menezes , Diego R O Alexandre, Júlio C B L Pinto, Tereza V L Assis, Avery D Faigenbaum, Arnaldo L Mortatti
Summary: The present study examined the effects of integrative neuromuscular training (INT) on motor performance in prepubertal soccer players. Subjects were randomly assigned to the experimental group (INT; n = 20, age: 8.2 ± 1.2 years; body mass: 28.4 ± 6.4 kg; height: 1.3 ± 0.1 m) or the control group (CON; n = 18, age: 8.5 ± 1.3 years; body mass: 32.8 ± 8.9 kg; height: 1.3 ± 0.1 m). Integrative neuromuscular training program was performed twice per week during the 12-week training intervention. Balance, flexibility, countermovement vertical jump height (CVJH), sprint speed, and change of direction speed (CODS) were assessed in both groups at baseline, sixth week and 12th week. A mixed model repeated measures analysis of variance was used to examine the group changes in performance for each variable. There was a time effect for balance in the INT from pre to 12th weeks (p < 0.001, g = 0.72), and from 6th to 12th weeks (p = 0.005, g = 0.34). An interaction effect for balance was also observed between INT and CON after the 12th week. A time effect in flexibility was observed in INT from baseline to 6th and 12th weeks (p = 0.02; g = 0.45 and p < 0.001; g = 0.71) and from 6 to 12th weeks (p = 0.003; g = 0.24). There was a time effect in CVJH, from baseline to 12th week and from 6th to 12th weeks (p < 0.05; g = 0.34 and g = 0.53, respectively). There was no significant between-group speed performance change. A time effect was found in CODS in INT, but only from baseline to 12th week (p = 0.02; g = 0.31). There were significant improvements in the percent change (Δ%) from baseline to 12 weeks (p < 0.05) for balance, flexibility, and CVJH in INT. These findings indicate that the addition of an INT program to soccer practice can improve selected motor performance skills in prepubertal soccer players.
#6 Exercise intensity and cardiovascular health outcomes after 12 months of football fitness training in women treated for stage I-III breast cancer: Results from the football fitness After Breast Cancer (ABC) randomized controlled trial
Reference: Prog Cardiovasc Dis. 2020 Aug 12;S0033-0620(20)30154-7. doi: 10.1016/j.pcad.2020.08.002. Online ahead of print.
Authors: Jacob Uth, Bjørn Fristrup, Victor Sørensen, Eva Wulff Helge, Maja Kjærgaard Christensen, Julie Boye Kjærgaard, Trine Kjeldgaard Møller, Magni Mohr, Jørn Wulff Helge, Niklas Rye Jørgensen, Mikael Rørth, Eva Soelberg Vadstrup, Peter Krustrup
Summary: The aim was to examine the exercise intensity and impact of 12 months of twice-weekly recreational football training on cardiorespiratory fitness (CRF), blood pressure (BP), resting heart rate (HRrest), body fat mass, blood lipids, inflammation, and health-related quality of life in women treated for early-stage breast cancer (BC). Sixty-eight women who had received surgery for stage I-III BC and completed adjuvant chemo- and/or radiation therapy within 5 years were randomized in a 2:1 ratio to a Football Fitness group (FFG, n = 46) or a control group (CON, n = 22). Football Fitness sessions comprised a warm-up, drills and 3-4 × 7 min of small-sided games (SSG). Assessments were performed at baseline, 6 months and 12 months. Outcomes were peak oxygen uptake (VO2peak), blood pressure (BP), HRrest, total body fat mass, and circulating plasma lipids and hs-CRP, and the 36-Item Short Form Health Survey (SF36). Intention-to-treat (ITT) analyses were performed using linear mixed models. Data are means with SD or 95% confidence intervals. Adherence to training in participants completing the 12-months follow-up (n = 33) was 47.1% (22.7), and HR during SSG was ≥80% of HRmax for 69.8% (26.5) of total playing time. At baseline, VO2peak was 28.5 (6.4) and 25.6 (5.9) ml O2/kg/min in FFG and CON, respectively, and no significant changes were observed at 6- or 12 months follow-up. Systolic BP (SBP) was 117.1 (16.4) and 116.9 (14.8) mmHg, and diastolic BP (DBP) was 72.0 (11.2) and 72.4 (8.5) mmHg in FFG and CON, respectively, at baseline, and a 9.4 mmHg decrease in SBP in CON at 12 months resulted in a between-group difference at 12 months of 8.7 mmHg (p = .012). Blood lipids and hs-CRP were within the normal range at baseline, and there were no differences in changes between groups over the 12 months. Similarly, no differences between groups were observed in HRrest and body fat mass at 6- and12-months follow-up. A between-group difference in mean changes of 23.5 (0.95-46.11) points in the role-physical domain of the SF36 survey favored FFG at 6 months CONCLUSION: Football Fitness training is an intense exercise form for women treated for breast cancer, and self-perceived health-related limitations on daily activities were improved after 6 months. However, 1 year of Football Fitness training comprising 1 weekly training session on average did not improve CRF, BP, blood lipids, fat mass, or HRrest.
#7 How has COVID-19 modified training and mood in professional and non-professional football players?
Reference: Physiol Behav. 2020 Aug 25;227:113148. doi: 10.1016/j.physbeh.2020.113148. Online ahead of print.
Authors: Daniel Mon-López, Abraham García-Aliaga, Alberto Ginés Bartolomé, Diego Muriarte Solana
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7445487/pdf/main.pdf
Summary: Coronavirus disease 2019 (COVID-19) has restricted freedom of movement with several countries 'locked down' worldwide. During this isolation period or quarantine, habits have been modified. This might have had negative effects on physiological variables but also influenced numerous emotional aspects, especially in elite athletes, which can have a negative impact on training and sleep quality, affecting their performance. 175 Spanish professional and non-professional association football players answered an online survey about demographic and training habits, as well as two validated questionnaires to assess psychological variables (POMS and WLEIS-S). The results showed that the confinement period reduced the load of training (p < 0.01), and modified the sleeping behaviour (both, sleep time (p < 0.05) and quality (p < 0.001)) across soccer players. Higher emotional intelligence (EI) values were positively related to training variables and strongly correlated with the mood. Interestingly, athletes' mood was affected differently depending on gender. We found that confinement period affects both, training load and recovery process and that mood states and EI could predict the training variables and performance of top-level football players.
#8 The association of the ACTN3 R577X and ACE I/D polymorphisms with athlete status in football: a systematic review and meta-analysis
Reference: J Sports Sci. 2020 Aug 28;1-12. doi: 10.1080/02640414.2020.1812195. Online ahead of print.
Authors: Alexander B T McAuley, David C Hughes , Loukia G Tsaprouni, Ian Varley, Bruce Suraci, Thomas R Roos, Adam J Herbert, Adam L Kelly
Summary: The aim of this review was to assess the association of ACTN3 R577X and ACE I/D polymorphisms with athlete status in football and determine which allele and/or genotypes are most likely to influence this phenotype via a meta-analysis. A comprehensive search identified 17 ACTN3 and 19 ACE studies. Significant associations were shown between the presence of the ACTN3 R allele and professional footballer status (OR = 1.35, 95% CI: 1.18-1.53) and the ACE D allele and youth footballers (OR = 1.18, 95% CI: 1.01-1.38). More specifically, the ACTN3 RR genotype (OR = 1.48, 95% CI: 1.23-1.77) and ACE DD genotype (OR = 1.29, 95% CI: 1.02-1.63) exhibited the strongest associations, respectively. These findings may be explained by the association of the ACTN3 RR genotype and ACE DD genotype with power-orientated phenotypes and the relative contribution of power-orientated phenotypes to success in football. As such, the results of this review provide further evidence that individual genetic variation may contribute towards athlete status and can differentiate athletes of different competitive playing statuses in a homogenous team-sport cohort. Moreover, the ACTN3 R577X and ACE I/D polymorphisms are likely (albeit relatively minor) contributing factors that influence athlete status in football.
#9 Evaluation of Gross Motor Coordination and Physical Fitness in Children: Comparison between Soccer and Multisport Activities
Reference: Int J Environ Res Public Health. 2020 Aug 14;17(16):E5902. doi: 10.3390/ijerph17165902.
Authors: Boris Popović, Marko Gušić, Danilo Radanović, Slobodan Andrašić, Dejan M Madić, Draženka Mačak, Dušan Stupar, Goran Đukić, Dragan Grujičić, Nebojša Trajković
Download link: https://www.mdpi.com/1660-4601/17/16/5902/pdf
Summary: The early detection and continuous monitoring of children's motor competence levels and physical fitness is very important. The purpose of this study was to determine the differences in motor coordination of children enrolled in soccer and multisport activities. The participants of this study included 147 boys and girls (mean age 7.60 ± 0.85 years). The total sample of subjects was composed of two subgroups: children who were enrolled in organized exercise programs-multisports (n = 77), and children who were engaged in soccer training (n = 70). Motor coordination was evaluated with the Kiphard-Schilling body coordination test (KTK). Physical fitness was assessed with a 20 m shuttle run test, 4 × 10 m shuttle run test, standing long jump, and handgrip strength. The ANCOVA showed significant differences (p < 0.05) with large effect size between groups for tests hopping for height (d = 0.93), total motor quotient (d = 1.31), jumping sideways (d = 1.32), and moving sideways (d = 1.59), after adjusting for age and gender. There were no significant differences between groups in the physical fitness tests. It can be concluded that children enrolled in multisport activities have higher levels of motor coordination than children who are enrolled only in soccer. Therefore, multiple sport training programs should be considered and encouraged by parents, educators, and other training professionals.
#10 A Fraction of Recommended Practices: Implementation of the FIFA 11+ in NCAA Soccer Programs
Reference: Medicina (Kaunas). 2020 Aug 19;56(9):E417.
Authors: Lawrence W Judge, Jeffrey C Petersen, Donald L Hoover, Bruce W Craig, Nick Nordmann, Makenzie A Schoeff , Brian D Fox, D Clark Dickin, David M Bellar
Download link: https://www.mdpi.com/1010-660X/56/9/417/pdf
Summary: National Collegiate Athletic Association (NCAA) soccer coaches implement numerous warm-up and flexibility strategies to prepare athletes for training and competition. The Fédération Internationale de Football Association (FIFA) developed the 11+ injury prevention program to reduce non-contact injuries. This study aimed to analyze the level of familiarity with and implementation of the evidence-based FIFA 11+ amongst NCAA Division I (DI) and Division III (DIII) men's and women's soccer coaches. NCAA soccer coaches in the United States received an Institutional Review Board-approved survey hyperlink. A total of 240 coaches completed the survey. The respondents represented 47.5% men's and 52.5% women's teams distributed within DI and DIII programs. Descriptive statistics are reported as frequency counts and mean ± standard deviation where applicable. Pearson's chi-square tests were performed to assess potential differences with a significance level set at α < 0.05. The results indicated that approximately 62% of the respondents reported being familiar with the FIFA 11+ program. Of those coaches familiar with the program, 15.0% reported full implementation, 57.5% reported partial implementation, and 27.5% reported no implementation. Chi-square analyses revealed significant differences in FIFA 11+ implementation based upon division level (χ2 = 4.56, p = 0.033) and coaching certification levels (χ2 = 13.11, p = 0.011). This study indicates that there is a gap between FIFA 11+ knowledge and actual implementation. To reduce the risk of non-contact injury, there is a need to educate coaches and athletic trainers on the purpose of the FIFA 11+ program and how to perform the exercises correctly.
#11 Power, Muscle, and Take-Off Asymmetry in Young Soccer Players
Reference: Int J Environ Res Public Health. 2020 Aug 19;17(17):E6040. doi: 10.3390/ijerph17176040.
Authors: Petr Bahenský, David Marko, Václav Bunc, Pavel Tlustý
Download link: https://www.mdpi.com/1660-4601/17/17/6040/pdf
Summary: The objective of the study was to check the relationship between laterality, amount of muscle mass (MM), and selected strength parameters on lower extremities and assessment of asymmetry like a result of training. The screened sample consisted of soccer players (n = 65, age = 16.0 ± 1.2 years). The legs were assessed for MM, height of reflection on a force plate, and power over 30 s Wingate anaerobic test (WAnT). The relationships between the individual parameters and age dependence were assessed using a correlation analysis. The differences between the dominant and non-dominant leg were assessed using the t-test. A relationship between the jump height and the mean 30 s power in WAnT (r = 0.375, p ˂ 0.01) and between the amount of MM and the absolute power of the individual legs in WAnT (r = 0.695-0.832, p ˂ 0.01) was proved. A relationship between the take-off force and the MM, or between the MM and the relative power during a velocity force load was not found. The amount of MM in young soccer players does not affect take-off force or strength power in WAnT. The more specific the movement is, the lower the effect on the achieved power output of the concerned MM. Differences in the performance between the dominant and non-dominant leg decrease with duration of the training.
#12 Reliability and Validity of a 6-Minute Yo-Yo Intermittent Endurance Test Level 2 in Subelite Part Time Male Soccer Players
Reference: J Strength Cond Res. 2020 Aug 18. doi: 10.1519/JSC.0000000000003641. Online ahead of print.
Authors: Neil Gibson, Chris Easton, Michael Williams, Robert McCunn , Neil V Gibson
Summary: The aim of this study was to assess the reliability and relationship to maximal intermittent running performance of the 6-minute Yo-Yo Intermittent Endurance Test Level 2 (YYIET2), among subelite part time soccer players. Twenty male soccer players (15-22 years) completed three 6-minute YYIET2 trials with heart rate (HR), PlayerLoad, and rating of perceived exertion assessed during the protocol and HR and blood lactate assessed during 5 minutes of recovery. Subjects also completed a maximal version of the YYIET2 and the maximal Yo-Yo Intermittent Recovery Test Level 1 (YYIRT1) and 2 (YYIRT2). Heart rate at 4 and 6 minutes, PlayerLoad at 4 minutes, and HR recovery at 2, 3, 4, and 5 minutes during recovery from the 6-minute YYIET2 demonstrated little variance between tests. Correlations between variables measured during and after the 6-minute YYIET2 and distance covered in maximal tests ranged from r = 0.02 to -0.72. The 6-minute YYIET2 provides practitioners with a method of reliably assessing HR responses within subelite part time soccer players, although large correlations with maximal assessments suggest it can be used as a proxy measure for maximal intermittent running performance. Given its ease of administration and low time cost, the 6-minute YYIET2 offers practitioners a useful means of tracking training status and movement efficiency in players longitudinally.
The aim was to compare heart rate, rating of perceived exertion and technical-tactical actions during SSGs played with and without goalkeepers.
The study investigated the effects of a 6-month school-based soccer program on cardiovascular and metabolic risk factors in overweight children.
Following studies were retrieved for this week:
#1 Reliability and Validity of Maximal Mean and Critical Speed and Metabolic Power in Australian Youth Soccer Players
Reference: J Hum Kinet. 2020 Jul 21;73:93-102. doi: 10.2478/hukin-2019-0135. eCollection 2020 Jul.
Authors: Cameron Lord, Anthony J Blazevich, Chris R Abbiss, Fadi Ma'ayah
Summary: The reliability and validity of maximal mean speed (MMS), maximal mean metabolic power (MMPmet), critical speed (CS) and critical metabolic power (CPmet) were examined throughout the 2016-2017 soccer National Youth League competitions. Global positioning system (GPS) data were collected from 20 sub-elite soccer players during a battery of maximal running tests and four home matches. A symmetric moving average algorithm was applied to the instantaneous velocity data using specific time windows (1, 5, 10, 60, 300 and 600 s) and peak values were identified. Additionally, CS and CP¬met values calculated from match data were compared to CS and CPmet values determined from previously validated field tests to assess the validity of match values. Intra-class correlation (one-way random absolute agreement) scores ranged from 0.577 to 0.902 for speed, and from 0.701 to 0.863 for metabolic power values. Coefficients of variation (CV) ranged from good to moderate for speed (4-6%) and metabolic power (4-8%). Only CS and CPmet values were significantly correlated (r = 0.842; 0.700) and not statistically different (p = 0.066; 0.271) to values obtained in a shuttle-running critical test. While the present findings identified match-derived MMS, MMPmet, CS and CPmet to be reliable, only CS and CPmet derived from match play were validated to a CS field test that required changes in speed and direction rather than continuous running. This suggests that both maximal mean and critical speed and metabolic power analyses could be alternatives to absolute distance and speed in the assessment of match running performance during competitive matches.
#2 Circulating Inflammatory Biomarkers and Endocrine Responses to Exercise in Female Soccer Players
Reference: J Hum Kinet. 2020 Jul 21;73:73-82. doi: 10.2478/hukin-2020-0005. eCollection 2020 Jul.
Authors: Grażyna Janikowska, Aleksandra Kochańska-Dziurowicz, Ilona Pokora, Aleksandra Żebrowska
Summary: The objective of the study to determine the effects of graded exercise on the cytokines and insulin-like growth factor-1 (IGF-1), growth hormone (hGH), testosterone (T), and cortisol (C) concentrations in the peripheral blood of female soccer players, and to evaluate if increased inflammatory biomarkers were related to these hormones and performance variables. Sixteen female soccer players (N = 16, age 19.3 ± 2.3 years) participated in this study. Blood samples were collected at three time points: pre-exercise, post-exercise, and in the 15th minute of recovery, to evaluate morphological and biochemical variables. The relative expression of IL-6 (interleukin 6) and serum concentrations of the cytokines were increased in the recovery period compared to pre-exercise levels (p = 0.03 and p=0.005, respectively). There was a significant effect of exercise on serum hGH level (p " 0.001), T/C ratio (p = 0.001), and C level (p=0.02). Positive correlations were found between: post-exercise IL-1β (interleukin 1 beta) and IL-6 (R = 0.84, p = 0.000), and the IL-6 and TNF-α (tumor necrosis factor alpha) gene expression during recovery (R = 0.65, p = 0.009), and serum IL-1β post-exercise and maximal power (R = 0.68; p = 0.004). Exercise-induced serum C levels positively correlated with IGF-1 levels (R = 0.52 p = 0.05). Negative associations were revealed between post-exercise T/C ratio and IGF-1 (R = - 0.58, p = 0.03) and serum free T and IL- β (R = -0.56, p = 0.04) levels. The low level of pre-exercise genes and protein of the IL-1β, IL-6 and TNF-α indicate a lack of inflammation signs in the female soccer players. This study shows significant effects of exercise on hormone levels and pro-inflammatory markers, which could be used to identify the role of female sex steroids on the immune function.
#3 Relationship Between the Session-RPE and External Measures of Training Load in Youth Soccer Training
Reference: J Strength Cond Res. 2020 Aug 6. doi: 10.1519/JSC.0000000000003785. Online ahead of print.
Authors: Jakub Marynowicz, Karol Kikut, Mateusz Lango , Damian Horna, Marcin Andrzejewski
Summary: The aim of this study was to identify the external training load (TL) markers (10 Hz Global Positioning System) that are most influential on the rating of perceived exertion (RPE) and session-RPE (sRPE) during youth soccer training. Data were collected from 18 youth soccer players during an 18-week in-season period. A total of 804 training observations were undertaken. We observed moderate to very large within-individual correlations between sRPE and measures of external load (r ranging from 0.36 to 0.76). Large, positive within-individual correlations were found between total covered distance, PlayerLoad, number of accelerations, and sRPE (r = 0.70, 0.64, and 0.62, respectively, p < 0.001). By contrast, small to moderate within-individual correlations were noted between RPE and measures of intensity (r ranging from 0.16 to 0.39). A moderate within-individual correlation was observed between high-speed running distance (HSR) per minute and RPE (r = 0.39, p < 0.001). The level of statistical significance was set at alpha = 0.05 for all tests. Two generalized estimating equation models were constructed, with RPE and sRPE as the response variables. The model identified by QIC for RPE contained 2 variables as follows: HSR per minute and distance in deceleration per minute, whereas sRPE was modeled with 3 predictors as follows: PlayerLoad, HSR, and distance in acceleration. The findings demonstrate that RPE does not reflect the intensity of a training session and that sRPE can be a useful, simple, and cost-effective tool for monitoring TL.
#4 Development and validation of the Referee Training Activity Questionnaire (RTAQ): Towards a better understanding of the training practices of soccer officials
Reference: J Sports Sci. 2020 Aug 10;1-12. doi: 10.1080/02640414.2020.1800371. Online ahead of print.
Authors: Gary P McEwan, Viswanath Unnithan, Chris Easton, Rosemary Arthur
Summary: The purpose was to develop and assess the validity of the Referee Training Activity Questionnaire (RTAQ), a systematic process was employed: 1) item generation; 2) assessments of content and face validity; and 3) assessments of criterion validity. In stage 1, items were generated following semi-structured interviews with an expert panel (n = 8). Following content analyses, the RTAQ was developed and comprised 3 primary sections (12 sub-sections) assessing: 1) attributes perceived to underpin soccer officiating performance; 2) general training information; and 3) specific training practices. In stage 2, the preliminary RTAQ was assessed for content and face validity by a sample of experts (n = 6). Based upon the content validity index (CVI), content validity was confirmed for 8 sub-sections (CVI ≥ 0.78) with 5 sub-sections being deemed invalid (CVI < 0.78). Various amendments were carried out in accordance with participant feedback. In stage 3, the RTAQ was completed by a cohort of officials (n = 25) who subsequently recorded a detailed training diary. Negligible mean biases, wide 95% LOA, and significant Pearson correlations were observed between the RTAQ and training diaries for most training activities, suggesting the RTAQ holds promise as a useful and effective alternative of acquiring insight into the training practices of soccer officials.
#5 Video assistant referees (VAR): The impact of technology on decision making in association football referees
Reference: J Sports Sci. 2020 Aug 14;1-7. doi: 10.1080/02640414.2020.1809163. Online ahead of print.
Authors: Jochim Spitz, Johan Wagemans, Daniel Memmert, A Mark Williams, Werner F Helsen
Summary: The use of technology has been proposed to improve decision-making in sport officials. The implementation of the video Assistant Referee (VAR) in association football is one example of how technology can be used to assist decision making, although its impact remains unknown. In 2195 competitive football matches across 13 countries, the VAR conducted 9732 checks for potential match-changing incidents, with the median duration of a check being 22 seconds. The checks resulted in a total of 795 reviews, with a median duration of 62.0 s for on-field reviews (N = 534) and 15.0 s for VAR-only reviews (N = 261).We report that the predictive odds for making the correct decision after VAR intervention were significantly higher than for the initial referee's decision, with accuracy increasing from 92.1% to 98.3%. Findings have implications for the current debate about the introduction of technology in association football and may help set guidelines regarding the use of technology across other sports and professional domains.
#6 What do you hear? The effect of stadium noise on football players' passing performances
Reference: Eur J Sport Sci. 2020 Aug 11;1-26. doi: 10.1080/17461391.2020.1809714. Online ahead of print.
Authors: Fabian W Otte, Sarah-Kate Millar, Stefanie Klatt
Summary: Stadium noise - created by spectators and fans - plays a critical part in the reality of professional sports. Due to a lack of research on the impact of these auditory cues and multimodal environments on motor performance, it is currently unclear how professional athletes experience and perceive stadium noise and how this potentially affects performance in practice. In order to explore the effect of stadium noise on athletes' performance, this paper presents an experimental design using the unique and standardised football training tool known as the 'Footbonaut'. Specifically, fifteen skilled German football players engaged in a standardised football-specific technical training program while subjected to four different auditory training conditions; these included both 'positive' and 'negative' stadium noise conditions, a 'baseline' condition providing auditory guidance, and a 'no (auditory) cue' condition. Performance data for passing accuracy and passing time were measured for training in each auditory condition. A repeated measures MANOVA revealed a significant main effect for passing time. Specifically, participants showed faster passing times in the baseline compared to the negative and no auditory cue conditions. Findings are presented and discussed from a constraints-led perspective, allied to principles of ecological dynamics and nonlinear pedagogy. Particularly, the use of representative training experiences (including multimodal sensory and emotional information) appears to underline training to refine expert athletes' adaptive coordination of complex motor actions.
#7 Neuropsychological Change After a Single Season of Head Impact Exposure in Youth Football
Reference: J Int Neuropsychol Soc. 2020 Aug 7;1-11. doi: 10.1017/S1355617720000685. Online ahead of print.
Authors: Arthur Maerlender, Eric Smith, P Gunnar Brolinson, Joseph Crisco, Jillian Urban, Amaris Ajamil, Steven Rowson, Eamon T Campolettano, Ryan A Gellner, Srinidhi Bellamkonda, Emily Kieffer, Mireille E Kelley, Derek Jones, Alex Powers, Jonathan Beckwith, Joel Stitzel, Richard M Greenwald, Stefan Duma
Summary: Head impact exposure (HIE) in youth football is a public health concern. The objective of this study was to determine if one season of HIE in youth football was related to cognitive changes. Over 200 participants (ages 9-13) wore instrumented helmets for practices and games to measure the amount of HIE sustained over one season. Pre- and post-season neuropsychological tests were completed. Test score changes were calculated adjusting for practice effects and regression to the mean and used as the dependent variables. Regression models were calculated with HIE variables predicting neuropsychological test score changes. For the full sample, a small effect was found with season average rotational values predicting changes in list-learning such that HIE was related to negative score change: standardized beta (β) = -.147, t(205) = -2.12, and p = .035. When analyzed by age clusters (9-10, 11-13) and adding participant weight to models, the R2 values increased. Splitting groups by weight (median split), found heavier members of the 9-10 cohort with significantly greater change than lighter members. Additionaly, significantly more participants had clinically meaningful negative changes: X2 = 10.343, p = .001. These findings suggest that in the 9-10 age cluster, the average seasonal level of HIE had inverse, negative relationships with cognitive change over one season that was not found in the older group. The mediation effects of age and weight have not been explored previously and appear to contribute to the effects of HIE on cognition in youth football players.
#8 Contextual factors influencing the characteristics of female football players
Reference: J Sports Med Phys Fitness. 2020 Jul 30. doi: 10.23736/S0022-4707.20.11182-4. Online ahead of print.
Authors: Jesse Griffin, Sean Horan, Justin Keogh, Karl Dodd, Melissa Andreatta, Clare Minahan
Summary: Women's football participation rates are projected to increase to 60 million worldwide by 2026, doubling the current participation. Growing investment and the increase in research in women's football has had a positive effect on the level of performance over the last 10 years. The present review will examine the literature on the physical and physiological characteristics of female football players from 2010 to 2019 to reflect the recent changes in professionalism. Characteristics investigated include anthropometry, strength, speed, endurance, power, change of direction and repeated sprint ability. These characteristics are presented in relation to playing position, age and competition-level. Results revealed that goalkeepers (171 cm, 66 kg) and defenders (168 cm, 61 kg) were the tallest and had the greatest body mass, while attackers were the fastest players over 20 m (3.05 s) and 30 m (4.38 s) and midfielders had the highest endurance (55.4 ml∙kg-1∙min-1) (p < 0.05). Characteristics tended to improve with age until full biological maturity around 17 to 18 years of age. Competition comparisons demonstrated international players have significantly greater speed, repeated sprint ability, power and endurance characteristics (p < 0.05). By identifying influential factors, coaches may be able to optimise their training and physical assessment practises, to better expose players to the required stimulus to develop these characteristics considered crucial to improved performance.
#9 Is the perception of intent by association football officials influenced by video playback speed?
Reference: R Soc Open Sci. 2020 Jun 3;7(6):192026. doi: 10.1098/rsos.192026. eCollection 2020 Jun.
Authors: George Mather, Simon Breivik
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7353977/pdf/rsos192026.pdf
Summary: Recent research on motion perception indicates that when we view actions in slow-motion, the perceived degree of intent behind those actions can increase. Slow-motion replays are widely used in the checking and review of refereeing decisions by video assistant referees (VAR) in association football. To test whether the decisions of referees are subject to such a bias, 80 elite English professional football officials made decisions about 60 incidents recorded in professional European leagues (recorded as fouls, yellow-card offences or red-card offences by the on-field referee). Both real-time (1×) and slow-motion (0.25×) playback speeds were used. Participants had no prior knowledge of the incidents, playback speeds or disciplinary sanctions relating to each clip. Three judgements were made about each incident: extent of contact, degree of intent, and disciplinary sanction. Results showed an effect of playback speed on decision-making, but not a consistent bias due to slow-motion. Instead the distinction between yellow-card and red-card offences was clearer: Under slow-motion, yellow-card incidents were judged as less severe, and red-card incidents are judged as more severe, thus enhancing the distinction between these offences. These results are inconsistent with previous scientific reports that perceived intent is heightened by slow video playback speed.
The main purpose was to assess the relations between training loads and selected blood parameters in professional players during a preseason sports camp.
The aim was to compare physiological parameters and technica-tactical actions during SSGs with and without wildcard players.
Following studies were retrieved for this week:
#1 The Interplay Between Plasma Hormonal Concentrations, Physical Fitness, Workload and Mood State Changes to Periods of Congested Match Play in
Professional Soccer Players
Reference: Front Physiol. 2020 Jul 21;11:835. doi: 10.3389/fphys.2020.00835. eCollection 2020.
Authors: Karim Saidi, Abderraouf Ben Abderrahman, Daniel Boullosa, Grégory Dupont, Anthony C Hackney, Benoit Bideau, Thomas Pavillon, Urs Granacher, Hassane Zouhal
Summary: The regular assessment of hormonal and mood state parameters in professional soccer are proposed as good indicators during periods of intense training and/or competition to avoid overtraining. The aim of this study was to analyze hormonal, psychological, workload and physical fitness parameters in elite soccer players in relation to changes in training and match exposure during a congested period of match play. Sixteen elite soccer players from a team playing in the first Tunisian soccer league were evaluated three times (T1, T2, and T3) over 12 weeks. The non-congested period of match play was from T1 to T2, when the players played 6 games over 6 weeks. The congested period was from T2 to T3, when the players played 10 games over 6 weeks. From T1 to T3, players performed the Yo-Yo intermittent recovery test level 1 (YYIR1), the repeated shuttle sprint ability test (RSSA), the countermovement jump test (CMJ), and the squat jump test (SJ). Plasma Cortisol (C), Testosterone (T), and the T/C ratio were analyzed at T1, T2, and T3. Players had their mood dimensions (tension, depression, anger, vigor, fatigue, confusion, and a Total Mood Disturbance) assessed through the Profile of Mood State questionnaire (POMS). Training session rating of perceived exertion (sRPE) was also recorded on a daily basis in order to quantify internal training load and elements of monotony and strain. Significant performance declines (T1 < T2 < T3) were found for SJ performance (p = 0.04, effect size [ES] ES1 - 2 = 0.15-0.06, ES2 - 3 = 0.24) from T1 to T3. YYIR1 performance improved significantly from T1 to T2 and declined significantly from T2 to T3 (p = 0.001, ES1 - 2 = 0.24, ES2 - 3 = -2.54). Mean RSSA performance was significantly higher (p = 0.019, ES1 - 2 = -0.47, ES2 - 3 = 1.15) in T3 compared with T2 and T1. Best RSSA performance was significantly higher in T3 when compared with T2 and T1 (p = 0.006, ES2 - 3 = 0.47, ES1 - 2 = -0.56), but significantly lower in T2 when compared with to T1. T and T/C were significantly lower in T3 when compared with T2 and T1 (T: p = 0.03, ES3 - 2 = -0.51, ES3 - 1 = -0.51, T/C: p = 0.017, ES3 - 2 = -1.1, ES3 - 1 = -1.07). Significant decreases were found for the vigor scores in T3 when compared to T2 and T1 (p = 0.002, ES1 - 2 = 0.31, ES3 - 2 = -1.25). A significant increase was found in fatigue scores in T3 as compared to T1 and T2 (p = 0.002, ES1 - 2 = 0.43, ES2 - 3 = 0.81). A significant increase was found from T1 < T2 < T3 intension score (p = 0.002, ES1 - 2 = 1.1, ES2 - 3 = 0.2) and anger score (p = 0.03, ES1 - 2 = 0.47, ES2 - 3 = 0.33) over the study period. Total mood disturbance increased significantly (p = 0.02, ES1 - 2 = 0.91, ES2 - 3 = 1.1) from T1 to T3. Between T1-T2, significant relationships were observed between workload and changes in T (r = 0.66, p = 0.003), and T/C ratio (r = 0.62, p = 0.01). There were significant relationships between performance in RSSAbest and training load parameters (workload: r = 0.52, p = 0.03; monotony: r = 0.62, p = 0.01; strain: r = 0.62, p = 0.009). Between T2-T3, there was a significant relationship between Δ% of total mood disturbance and Δ% of YYIR1 (r = -0.54; p = 0.04), RSSAbest (r = 0.58, p = 0.01), SJ (r = -0,55, p = 0.01), T (r = 0.53; p = 0.03), and T/C (r = 0.5; p = 0.04). An intensive period of congested match play significantly compromised elite soccer players' physical and mental fitness. These changes were related to psychological but not hormonal parameters; even though significant alterations were detected for selected measures. Mood monitoring could be a simple and useful tool to determine the degree of preparedness for match play during a congested period in professional soccer.
#2 Building social cohesion between Christians and Muslims through soccer in post-ISIS Iraq
Reference: Science. 2020 Aug 14;369(6505):866-870. doi: 10.1126/science.abb3153.
Authors: Salma Mousa
Summary: Can intergroup contact build social cohesion after war? I randomly assigned Iraqi Christians displaced by the Islamic State of Iraq and Syria (ISIS) to an all-Christian soccer team or to a team mixed with Muslims. The intervention improved behaviors toward Muslim peers: Christians with Muslim teammates were more likely to vote for a Muslim (not on their team) to receive a sportsmanship award, register for a mixed team next season, and train with Muslims 6 months after the intervention. The intervention did not substantially affect behaviors in other social contexts, such as patronizing a restaurant in Muslim-dominated Mosul or attending a mixed social event, nor did it yield consistent effects on intergroup attitudes. Although contact can build tolerant behaviors toward peers within an intervention, building broader social cohesion outside of it is more challenging.
#3 Family History of Hypertension Impairs the Autonomic Balance, but not the Endothelial Function, in Young Soccer Players
Reference: Arq Bras Cardiol. 2020 Jul;115(1):52-58. doi: 10.36660/abc.20180441. Epub 2020 Aug 7.
Authors: Walter Vargas , Katya Rigatto
Summary: Background The family history of hypertension (FHH) imposes consistent risk for diverse chronic diseases that are accompanied by hypertension. Furthermore, the heart rate variability (HRV) and flow-mediated dilation (FMD) are both related to maximal oxygen uptake (VO2max), and are usually impaired during hypertension Objective To compare the autonomic modulation, the endothelial function (EF) and maximum oxygen uptake (VO2max) of young athletes, separated according to their parents' blood pressure (BP) history, in order to study the influence of their genetic background on those parameters. Methods A total of 46 young male soccer players (18±2 years of age) were divided into four groups: 1-normotensive father and mother (FM-N); 2-only father was hypertensive (F-H); 3-only mother was hypertensive (M-H); 4-father and mother were hypertensive (FM-H). Measurements of BP, FMD, HRV and VO2maxwere performed. The significance level adopted in the statistical analysis was 5%. Results The standard deviation of normal RR intervals (SDNN; FM-N=314±185; FM-H=182.4± 57.8), the square root of the mean squared differences in successive RR intervals (RMSSD; FM-N=248±134; FM-H=87±51), the number of interval differences of successive NN intervals greater than 50ms (NN50; FM-N=367±83.4; FM-H=229±55), the ratio derived by dividing NN50 by the total number of NN intervals (pNN50; FM-N=32.4±6.2; FM-H=21.1±5.3) and the high (HF; FM-N=49±8.9; FM-H=35.3±12) and low-frequency (LF; FM-N=50.9±8.9; FM-H=64.6±12) components, in normalized units (%), were significantly lower in the FM-H group than in the FM-N group (p<0.05). On the other hand, the LF/HF ratio (ms2) was significantly higher (p<0.05). We found no significant difference between the groups in VO2maxand FMD (p<0.05). Conclusions In young male soccer players, the FHH plays a potentially role in autonomic balance impairment, especially when both parents are hypertensive, but present no changes in VO2maxand FMD. In this case, there is a decrease in the sympathetic-vagal control, which seems to precede the endothelial damage (Arq Bras Cardiol. 2020; 115(1):52-58).
#4 Anthropometric and Functional Profile of Selected vs. Non-Selected 13-to-17-Year-Old Soccer Players
Reference: Sports (Basel). 2020 Aug 9;8(8):E111. doi: 10.3390/sports8080111.
Authors: Erik Nughes, Vincenzo Rago, Rodrigo Aquino , Georgios Ermidis, Morten B Randers, Luca Paolo Ardigò
Summary: The purpose of this study was to compare anthropometric and functional profiles of 13-to-17-year-old soccer players according to their competitive level. Height, body mass, percentage of body fat, countermovement jump height, change of direction ability, 5- and 15-m sprint times, repeated sprint ability (RSA), intermittent recovery performance, and dribbling skills were collected in 115 young Italian soccer players. Players were divided into selected (i.e., competing at national level, n = 17 U15 and 47 U17) and non-selected (i.e., competing at regional level, n = 43 U15 and 8 U17) groups. U17 selected players were taller, quicker over 5 and 15 m, more agile, and had better RSA, prolonged intermittent recovery ability, and dribbling skills than their non-selected counterparts (d = 0.28-0.55, p < 0.05). In particular, selected players showed lower times on the first three and the last shuttle of the RSA test (d = 0.28-0.34, p < 0.05). No significant differences were observed in U15 players (p > 0.05). Discriminant analysis revealed that dribbling skills, 15-m sprint time, and height best discriminate U17 players by competitive level (p < 0.001). Anthropometric characteristics and functional abilities can discriminate across competitive standards between male U17 but not U15 soccer players. In particular, these findings suggest the importance of dribbling skills, 15-m sprint, and height in U17 players.
#5 The use of technology in tracking soccer players' health performance: a scoping review
Reference: BMC Med Inform Decis Mak. 2020 Aug 11;20(1):184. doi: 10.1186/s12911-020-01156-4.
Authors: Jassim Almulla, Abdulrahman Takiddin, Mowafa Househ
Summary: Quantifying soccer players' performance using different types of technologies helps coaches in making tactical decisions and maintaining players' health. Little is known about the relation between the performance measuring technologies and the metrics they measure. The aim of this study is to identify and group the different types of technologies that are used to track the health-related performance metrics of soccer players. We conducted a systematic search for articles using IEEE Xplore, PubMed, ACM DL, and papers from the Sports Medicine Journal. The papers were screened and extracted by two reviewers. The included papers had to fall under several criteria, including being about soccer, measuring health-related performance, and using technology to measure players' performance. A total of 1,113 papers were reviewed and 1,069 papers were excluded through the selection process. We reviewed 44 papers and grouped them based on the technology used and health-related metrics tracked. In terms of technology, we categorized the used technologies into wearable technologies (N=27/44) and in-field technologies (N=14/44). We categorized the tracked health-related metrics into physiological metrics (N=16/44) and physical metrics (N=44/44). We found out that wearable technologies are mainly used to track physical metrics (N=27/27) and are also used to track physiological metrics (N=14/27). In-field technologies are only used to track physical metrics (N=24/24). Understanding how technology is related to players' performance and how it is used leads to an improvement in the monitoring process and performance outcomes of the players.
#6 Soccer heading and concussion are not associated with reduced brain volume or cortical thickness
Reference: PLoS One. 2020 Aug 10;15(8):e0235609. doi: 10.1371/journal.pone.0235609. eCollection 2020.
Authors: Tiago Gil Oliveira, Chloe Ifrah, Roman Fleysher, Michael Stockman, Michael L Lipton
Summary: Soccer is the most popular sport in the world and, since it is a contact sport, players are at risk for head injury, including concussion. Here, we proposed to investigate the association of heading and concussion with macroscopic brain structure among adult amateur soccer players. For this study, 375 amateur soccer players (median age 23 years) completed HeadCount-12m to estimate heading over the 12 months prior to MRI and lifetime concussion. T1-weighted 3D magnetization prepared rapid acquisition gradient echo (MP-RAGE) MRI was performed at 3 Tesla. Parcellation was performed using Freesurfer to extract regional gray and white matter volumes as well as regional cortical thickness and total intracranial volume. Regional cortical brain volumes were normalized by total intracranial volume. We categorized heading into quartiles and concussion as 0, 1 or 2 or more. Generalized linear regressions were used to test the association of heading or concussion with each brain morphometry metric, including age and sex, as covariates. Neither heading nor concussion were associated with reduced brain volume or cortical thickness. We observed that greater heading was associated with greater gray matter volume in the left inferior parietal area, which may reflect effects related to training.
#7 Effects of Training with an Agility Ladder on Sprint, Agility, and Dribbling Performance in Youth Soccer Players
Reference: J Hum Kinet. 2020 Jul 21;73:219-228. doi: 10.2478/hukin-2019-0146. eCollection 2020 Jul.
Authors: Alexis Padrón-Cabo, Ezequiel Rey, Anton Kalén, Pablo B Costa
Summary: The aim of this study was to examine the effects of coordination training using an agility ladder compared with a control group on physical fitness and technical performance in youth soccer players. Eighteen male youth soccer players (age: 12.2 ± 0.4 years; body height: 158.3 ± 10.8 cm; body mass: 45.0 ± 8.0 kg) were randomly assigned to an agility ladder group (n = 10) or a control group (n = 8). The intervention program was carried out three times a week over six weeks. Before and after the training period, the 10 m sprint, 20 m sprint, dribbling speed test, agility test, and slalom dribbling test performances were assessed. Within-group analysis showed significant improvements (p < 0.005) in 10 m and 20 m sprint performance from the pre- to the post-test for the agility ladder group (-2.39% and -2.10%) and the control group (-2.54% and -1.44%). No significant differences (p > 0.005) were found from the pre- to the post-test in the dribbling speed test, agility test, slalom dribbling test, and skill index. In the between-group analysis, there were no differences between the agility ladder group and the control group in any variable. In conclusion, the findings of this study suggest coordination training with an agility ladder does not seem to be effective to improve physical fitness and dribbling. Therefore, this information could be beneficial to players and coaches for programming tasks during soccer training sessions.
#8 Evidence for the Relative Age Effect in the Spanish Professional Soccer League
Reference: J Hum Kinet. 2020 Jul 21;73:209-218. doi: 10.2478/hukin-2019-0145. eCollection 2020 Jul.
Authors: José María Yagüe, Olga Molinero, José Ángel Alba, Juan Carlos Redondo
Summary: The concept of the relative age effect refers to the consequences of the physical and psychological differences that may exist between those born earlier or later within the same calendar year. The objective of the present study was to examine this phenomenon in Spanish professional soccer, identifying the influences of the competitive level and the club of origin. The sample comprised 2,130 individuals from five competitive categories: under 12 (U12; n = 480), under 14 (U14; n = 338), under 16 (U16; n = 390), under 19 years old (U19; n = 489) and professional players (n = 433), with nine teams from the Spanish professional soccer league (PSL). Statistical analysis was based on a chi-squared test followed by calculation of the odds ratios and 95% confidence intervals. The main results show that at all levels of competition there was over-representation of individuals born in the first few months of the year. By clubs, the same over-representation was observed. It may be concluded that the relative age effect is consistent and exists throughout Spanish soccer, whether at youth or professional levels. An analysis by age categories showed a more pronounced effect in those competitions in which the youngest players participate, while in clubs the effect continued to be significantly present in all cases investigated in the study.
#9 A Comparison of Incremental Running Field and Treadmill Tests in Young Soccer Players
Reference: J Hum Kinet. 2020 Jul 21;73:193-201. doi: 10.2478/hukin-2019-0143. eCollection 2020 Jul.
Authors: Yusuf Köklü, Utku Alemdaroğlu, Ramazan Demirhan, Yunus Arslan
Summary: The purpose of this study was to compare the incremental running tests performed by young soccer players on a treadmill (Tr) and in the field (FTcod: 100 m change of direction and FTcir: 100 m circle). Nineteen players (average age 17.4 ± 1.1 years; body height 172.0 ± 5.7 cm; body mass 68.9 ± 6.7 kg) volunteered to perform incremental Tr , FTcod and FTcir running tests. In all three tests, players ran for 3 min at 8, 10, 12 and 14 km∙h-1 and were given a 1 min rest interval between subsequent stages. Blood lactate concentrations (La-) were measured at 1 min rest intervals and the heart rate (HR) responses of players were recorded during the tests. After a 5 min recovery period, the second part of the test started; players ran at 15 km∙h-1 with velocity increments of 1 km∙h-1 every 1 min until exhaustion. This part was performed to determine maximum HR, maximum La- and the players' final velocities. The results showed that players had significantly lower La- (F = 6.93, p = 0.07, η2 = 0.46, 95%CI(TR-FTcir) = -1.91/-0.34, 95%CI(TR-FTcod) = -1.59/-0.05) and HR (F = 9.08, p = 0.02, η2 = 0.53, 95%CI(TR-FTcir) = -6.98/-1.68, 95%CI(TR-FTcod) = -7.19/1.08) responses in the Tr test than in the FTcir and FTcod tests at 14 km∙h-1. It was also found that players completed the Tr test (F = 58.22, p = 0.00, η2 = 0.87) at higher final running velocities than the FTcir (95%CI(TR-FTcir) = 1.67/2.78) and FTcod (95%CI(TR-FTcod) = 1.69/2.85) tests. In conclusion, when coaches or sports scientists plan to train at higher running velocities or according to the final velocity in the test, it is advisable to carry out testing in the circumstances under which training will be carried out (in the field or on a treadmill).
#10 How do Elite Soccer Teams Perform to Ball Recovery? Effects of Tactical Modelling and Contextual Variables on the Defensive Patterns of Play
Reference: J Hum Kinet. 2020 Jul 21;73:165-179. doi: 10.2478/hukin-2019-0141. eCollection 2020 Jul.
Authors: Tiago Fernandes, Oleguer Camerino, Júlio Garganta, Raúl Hileno, Daniel Barreira
Summary: Researchers in soccer match analysis have been using limited procedures to express the dynamics of the game and mainly focus on the attack. Therefore, the aims of this paper were to detect the successful teams' ball recovery defensive patterns of play and study the influence of tactical modelling, halves, match status, opponent quality and stage competition on those patterns. The sample consisted of 1323 situations of defensive ball possession of the semi-finalist teams from the 2014 FIFA World Cup play-offs, which was collected by a valid and reliable observational instrument (Soccer-Defence). The Kruskal-Wallis H, Mann-Whitney U, Chi-square, Z-, multinomial logistic regression tests and sequential analysis (p < .05; z > 1.96) were used accordingly to test the differences and associations among and within teams of tactical modelling, tactical-technical behaviours and contextual variables to ball recovery. We found that among teams ball recovery differed in duration; H(3) = 14.958, p = .002. Germany were more likely to perform ball recovery by the goalkeeper than Argentina (p = .04; OR = 0.47) or the Netherlands (p < .05; OR = 0.50). Nevertheless, Brazil was the least likely to concede a shot off goal. Teams facing lower-ranked opponents were 0.63 times less likely to perform ball recovery by interception (p <.001). Additionally, sequential analysis illustrated that teams varied between central and lateral high-pressure zones before ball recovery in lower zones of the field. Finally, coaches could use such findings to design training exercises, create their own style of play, and set strategies.
The purpose of this study was to investigate the association between offensive tactical knowledge and the soccer-specific motor skills performance.
Predicting the defensive performance of individual players in one vs. one soccer games.
Following studies were retrieved for this week:
#1 How Numerical Unbalance Constraints Physical and Tactical Individual Demands of Ball Possession Small-Sided Soccer Games
Reference: Front Psychol. 2020 Jul 14;11:1464. doi: 10.3389/fpsyg.2020.01464. eCollection 2020.
Authors: Nuno André Nunes, Bruno Gonçalves, Diogo Coutinho, Bruno Travassos
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7371931/pdf/fpsyg-11-01464.pdf
Summary: This study aimed to explore the effects of playing different unbalanced ball possession small-sided games on external workload (distance covered while walking, running, and sprinting, and max speed), tactical individual actions (number of passes with dominant and non-dominant foot), and internal load (rating of perceived exertion, RPE) in under-23 soccer players. Participants played 4v2, 4v3, 4v4, 4v5, and 4v6 small-sided games (SSGs) on a 30 × 25 m playing area. Data were analyzed under an opponent-based perspective, by fixing one team (4vX), and by cooperation-based perspective according to teammates (4v2+X). Global Position System (GPS) monitors were used to collect and compute external workloads and individual tactical actions, and Borg Scale CR10 was used to evaluate RPE. High-Superiority (4v2), Superiority (4v3), and Very Low-Cooperation (4v2+0) formats allow players in balanced teams to cover more distance while walking; on the other side, Inferiority (4v5), High-Inferiority (4v6), and Very High-Cooperation (4v2+4) allow players to sprint more and practice more tactical individual actions as a resultant emergent behavior; all players in SSG conditions with a lower number of conditions, perceived the exercise as more intense, especially in situations with less than two players. Overall, playing in high inferiority situations (4v2 and 4v6) may be used to increase physical demand for the outnumbered team, while coaches may use low superiority situations to adjust the task complexity when developing the players' tactical individual actions.
#2 Acute Effects of ACL Injury-Prevention Warm-Up and Soccer-Specific Fatigue Protocol on Dynamic Knee Valgus in Youth Male Soccer Players
Reference: Int J Environ Res Public Health. 2020 Aug 4;17(15):E5608. doi: 10.3390/ijerph17155608.
Authors: Marco Andrés García-Luna , Juan Manuel Cortell-Tormo, Miguel García-Jaén, Manuel Ortega-Navarro, Juan Tortosa-Martínez
Download link: https://www.mdpi.com/1660-4601/17/15/5608/pdf
Summary: Childhood anterior cruciate ligament (ACL) injuries-which can pose a major risk to a child's sporting career-have been on the rise in the last few decades. Dynamic knee valgus (DKV) has been linked to an increased risk of ACL injury. Therefore, the aim of this study was to analyze the acute effects of an ACL injury prevention protocol (ACL-IPP) and a soccer-specific fatigue protocol (SSFP) on DKV in youth male soccer players. The research hypothesis was that DKV would be reduced by the ACL-IPP and increased by the SSFP. Eighteen youth male soccer players were divided according to baseline DKV. Those with moderate or large DKV performed a neuromuscular training protocol based on activation of the abductor and external rotator hip muscles. Those with little or no DKV performed a soccer-specific fatigue protocol. DKV was assessed using the single-leg squat pre- and post-protocols in both legs. The ACL-IPP significantly decreased DKV during single-leg squat (p < 0.01, effect size = 1.39), while the SSFP significantly increased baseline DKV in the dominant leg during single-leg squat (p = 0.012; effect size = 1.74). In conclusion, the ACL-IPP appears to acutely reduce the DKV in youth male soccer players, and the SSFP seems to acutely increase the DKV in those players who showed a light or no DKV in a non-fatigue situation. By using the SSFP, it may be possible to determine which players would benefit from injury prevention programs due to increased DKV during game scenarios, while hip abductor and external rotator neuromuscular training may be beneficial for players who have moderate and severe DKV during single-leg squat under non-fatigued scenarios.
#3 Short-Term Compound Training on Physical Performance in Young Soccer Players
Reference: Sports (Basel). 2020 Jul 30;8(8):E108. doi: 10.3390/sports8080108.
Authors: Athos Trecroci, Marco Duca, Damiano Formenti, Giampietro Alberti, F Marcello Iaia, Stefano Longo
Download link: https://www.mdpi.com/2075-4663/8/8/108/pdf
Summary: This study aimed to investigate the effects of a five-week compound training (with strength and plyometric exercises performed on separate days) on sprint, change of direction, and vertical jump in young soccer players. Eighteen novices in strength and plyometric training were assigned to either a compound training (CMPT) or a control condition (CNT). Both groups trained three times per week. One session was dedicated to soccer-specific drills. The other two weekly sessions were dedicated to circuit-based training routines employing on one-day strength exercises and on the other day plyometric exercises in the CMPT group. At the same time, the CNT group performed two weekly soccer-specific training sessions. All players were tested by 15-m sprint, change-of-direction and acceleration test (CODAT), squat jump, and countermovement jump with arms swing tests. CMPT group improved CODAT, squat jump and countermovement jump to a higher extent compared to CNT group (large vs small or trivial effects, p < 0.05), while both groups had similar 15-m sprint performance (p > 0.05). These results support the use of compound training to improve change of direction and vertical jump performances in young novice soccer players, which are unfamiliar with structured and advanced strength and plyometric training.
#4 A Longitudinal Prospective Study: The Effect of Annual Seasonal Transition and Coaching Influence on Aerobic Capacity and Body Composition in Division I Female Soccer Players
Reference: Sports (Basel). 2020 Jul 30;8(8):E107. doi: 10.3390/sports8080107.
Authors: Troy M Purdom, Kyle S Levers, Chase S McPherson, Jacob Giles, Lindsey Brown
Download link: https://www.mdpi.com/2075-4663/8/8/107/pdf
Summary: This study assessed how seasonal transitions and coaching influence affect aerobic capacity (AC) and body composition across the annual training cycle (ATC). Eleven division 1 female soccer players were tested after five predesignated time blocks (B1-B5): post-season 2016 (B1), nine-week transition (B2), spring season (B3), pre-season (B4), and post-season 2017 (B5). Height, weight, and body composition (fat-free mass (FFM)) were measured prior to a standardized 5 min treadmill running and dynamic movement warm up before a maximal AC test. Statistical analysis included a 4 × 5 repeated-measures analysis of variance (ANOVA) (dependent variable × time) with the Fishers Least Significant Difference (LSD) post-hoc test when relevant; data are presented as mean ± standard deviation, effect size (ES), and percent change (%). The statistical analysis revealed that the ATC had a significant main effect on AC and FFM (F3,4 2.81, p = 0.001; η2 = 0.22). There were significant increases in AC across the transition period (B1-B2) with reduced training volume (∆ + 12.9%, p = 0.001; ES = 0.50) while AC and FFM peaked after the spring season with directed concurrent training paired with adequate rest B1-B3 (∆ + 16.4%, p < 0.01; ES = 0.81). AC decreased across the pre-season with indirect training (B3-B4) (∆ - 7.0%, p = 0.02; ES = 0.50) and remained suppressed without change (p > 0.05) across the competitive season (B4-B5). Rest, concurrent training, and directed training positively affected AC, while indirect training and high training loads with little rest negatively affected AC.
#5 Does the distribution of the weekly training load account for the match results of elite professional soccer players?
Reference: Physiol Behav. 2020 Aug 1;225:113118. doi: 10.1016/j.physbeh.2020.113118. Online ahead of print.
Authors: Rafael Oliveira, João P Brito, Nuno Loureiro, Vitor Padinha, Bruno Ferreira, Bruno Mendes
Summary: The aim of the study was to compare training load (TL) of the days preceding a win, draw or defeat in a sample of elite professional soccer players across the in-season 2015/16. Twenty elite soccer players participated in this study. Total distance covered, high-speed running distance (HSRD), average speed, session rate of perceived exertion (s-RPE) and Hooper index scores (HI) were collected. Data from 24 weeks with one match were analysed through the match-day (MD-5, 4, 3, 2, 1) and MD+1. The main finding emerges in MD-1, where a longer training duration preceding draws (95.1 ± 1.5 min) > defeats (91.5 ± 1.6 min) > wins (84.7 ± 0.5 min) was found, while total distance and average speed were higher in wins (3628.6 ± 57.2 m) > draws (3391.3 ± 153.3 m) > defeats (3236.1 ± 113.7 m) and draws (130.7 ± 17.6 m/min) > wins (86.0 ± 6.9 m/min) > defeats (54.8 ± 7.1 m/min), respectively. HSRD was higher in draws (42.8 ± 0.6 m) > wins (36.1 ± 1.7 m) > defeats (35.8 ± 1.7 m). In MD+1, there were differences in HI between wins vs draws (p<0.01). The results are drawn from one team that participated in UEFA Champions League. It was observed that different TL applied in training sessions can influence match result. Our findings can be considered in future soccer planning and periodization to win matches. This study emphasizes the use of HI especially in the day following the match.
#6 Description of acute and chronic load, training monotony and strain over a season and its relationships with well-being status: A study in elite under-16 soccer players
Reference: Physiol Behav. 2020 Aug 1;225:113117. doi: 10.1016/j.physbeh.2020.113117. Online ahead of print.
Authors: Hadi Nobari, Rodrigo Aquino, Filipe Manuel Clemente, Mousa Khalafi, Jose Carmelo Adsuar, Jorge Pérez-Gómez
Summary: This study described the weekly variations of acute (wAL), chronic (wCL), acute:chronic workload ratio (wACWR), training monotony (wTM), and training strain (wTS) of perceived load, such as wellness indicators over a competitive season. In addition, we analyzed the associations between training load metrics and weekly reports. Twenty-nine under 16 years old elite players were daily monitored for 20 consecutive weeks during the season by individual observations. Training and match load were obtained using the session rating of perceived exertion. Well-being status relative to stress, fatigue, delayed onset muscle soreness (DOMS), and sleep quality/disorders were daily monitored using the Hooper index method. The results revealed that the highest values of wAL, wCL, and wTS were verified in the mid-season and the lowest values in the start-season. The highest values of accumulated weekly fatigue, stress, and DOMS were observed in the end-season, and the lowest values of sleep and stress in the start-season while the lowest values of fatigue and DOMS were observed in the mid-season. Regarding the load variability, the results showed the highest values between-week variations to wTS (15%; week-8 to 9) and the lowest reduction to wACWR (-19%; week-9 to 10). The highest within-week variations were verified to wACWR (coefficient of variation =19%; week-18) and the lowest to wCL (coefficient of variation =6%, week-19). Wellness indicators were moderate-large related to acute load, monotony and strain (r = 0.46-0.67). Overall Hooper index was the best predictor of the acute load (R2 = 0.45). These results provide new insights for coaches and practitioners about perceived loads and well-being variations over a season in elite youth level.
#7 Upper respiratory symptoms (URS) and salivary responses across a season in youth soccer players: A useful and non-invasive approach associated to URS susceptibility and occurrence in young athletes
Reference: PLoS One. 2020 Aug 4;15(8):e0236669. doi: 10.1371/journal.pone.0236669. eCollection 2020.
Authors: Renata Fiedler Lopes, Luciele Guerra Minuzzi, António José Figueiredo, Carlos Gonçalves, Antonio Tessitore, Laura Capranica, Ana Maria Teixeira, Luis Rama
Download link: https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0236669&type=printable
Summary: This study examined the effect of a competitive season on salivary responses [cortisol (sC), testosterone (sT), Testosterone/Cortisol ratio (sT/C), Immunoglobulin A (sIgA), sIgA secretion rate (srIgA), alpha-amylase (sAA)] and upper respiratory symptoms (URS) occurrence in three teams of male soccer players (Under-15, Under-17 and Under-19 yrs.). Training and competition volumes, salivary biomarkers and URS were determined monthly. No differences were found for monthly training volume between teams. Incidence of URS was higher for the U15 (44.9% of the total cases). Higher sT and srIgA were observed for the U19, lower sC were found for the U17 and sAA showed higher values for the U15 throughout the season. In the U15, significant difference (p = .023) was found for sIgA concentration with higher concentration values in January compared to December (-42.7%; p = .008) and the sT showed seasonal variation (p < .001) with the highest value in January significantly different from October (-40.2%; p = .035), November (-38.5%; p = 0.022) and December (-51.6%; p = .008). The U19 presented an increase in sC in March compared to February (-66.1%, p = .018), sT/C were higher in February compared to March (-58.1%; p = .022) and sAA increased in March compared to September (-20.5%; p = .037). Negative correlations, controlled for age group, were found between URS occurrence and srIgA (r = -0.170, p = .001), sAA (r = -0.179, p = .001) and sT (r = -0.107, p = .047). Monitoring salivary biomarkers provides information on mucosal immunity with impact in URS occurrence. Coaches could manipulate training loads to attenuate the physical stressors imposed on athletes, especially at demanding and stressful periods.
#8 The effects of an integrative training program on elite young soccer players' physical performance
Reference: J Sports Med Phys Fitness. 2020 Jul 30. doi: 10.23736/S0022-4707.20.11195-2. Online ahead of print.
Authors: Christos Karydopoulos, Dimitrios Kapralos, Evangelia Kouidi, Yiannis Michailidis, Thomas Metaxas
Summary: The aim of this study was to investigate the effects of a short duration and low weekly frequency integrative program on sprint, agility and jump performance in elite youth soccer players. Twenty-eight elite youth soccer players, members of two professional clubs, playing in the U19 developmental championship participated in this study. They were divided into 2 groups: the intervention group (EG,n=15) and the control group (CG, n=13). The duration of the intervention program was 8 weeks with a frequency of twice per week. The performance of the participants in the 10 meters and 30 meters speed, countermovement jump (CMJ), squat jump (SJ) and agility (Illinois agility test, Arrowhead agility test) was measured at the beginning and the end of the 8-week study. There was no statistically significant difference in any performance measured between the two groups. The results of the present study indicate that the addition of allowing frequency and short duration training intervention program did not enhance the physical fitness indicators, in high-level young soccer players.
#9 Virtual immersive sensorimotor training (VIST) in collegiate soccer athletes: A quasi-experimental study
Reference: Heliyon. 2020 Jul 24;6(7):e04527. doi: 10.1016/j.heliyon.2020.e04527. eCollection 2020 Jul.
Authors: Jennifer C Reneker, W Cody Pannell, Ryan M Babl , Yunxi Zhang, Seth T Lirette, Felix Adah, Matthew R Reneker
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7385459/pdf/main.pdf
Summary: A burgeoning area of innovation in sports is the use of extended realities to provide athletes with novel training environments. Evidence has demonstrated that virtual environments can be useful therapeutic tools with demonstrated positive outcomes. The purpose of this pilot investigation was to determine the effects of virtual immersive sensorimotor training intervention by quantifying 1) the training effect measured via change in performance pre-to post-intervention on the virtual reality exercises, 2) the difference in the in clinical measures of functional sensorimotor control, 3) the injury incidence rate, and 4) on-field performance during soccer competitions. Statistical analyses were used to describe differences between an experimental and a control group. Participants were recruited from the men and women's soccer teams at two universities in the United States. Participants at one university were in the experimental group (n = 78) and received virtual immersive sensorimotor training, consisting of nine novel exercises in headset virtual reality, twice each week for six weeks. Participants at the second university were in the control group (n = 52). The virtual exercises were developed with reference to the rehabilitative principles of neuroplasticity to train various neurologic processes, contributing to overall sensorimotor control. This includes vestibular, visual and oculomotor activities, cervical neuromotor control training, movement coordination, and postural/balance exercises. The results indicate significant positive training effects pre-to post-intervention in seven of the nine training exercises (p ≤ 0.005) and improvement in clinical tests of cervical neuromotor control, balance, and inspection time (p ≤ 0.009) in the experimental group compared to the control. One of the virtual training exercises was positively associated with on-field performance (p = 0.022). No differences in injury rate or overall on-field performance metrics between the experimental and control were detected. This research study provides evidence of training and positive transfer from virtual to real-world environments, supporting the use of these novel virtual exercises to improve measures of sensorimotor control in healthy soccer athletes.
#10 Acceleration and sprint profiles of professional male football players in relation to playing position
Reference: PLoS One. 2020 Aug 6;15(8):e0236959. doi: 10.1371/journal.pone.0236959. eCollection 2020.
Authors: José M Oliva-Lozano, Víctor Fortes, Peter Krustrup, José M Muyor
Download link: https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0236959&type=printable
Summary: The study aims were to describe positional differences in the acceleration and sprint profiles of professional football players in match-play, and analyse start speeds required based on the intensity of accelerations and decelerations. This longitudinal study was conducted over thirteen competitive microcycles in a professional football team from LaLiga 123. Data were collected through electronic performance tracking systems. Every player was categorised based on the playing position: central defender (CD), full-back (FB), forward (FW), midfielder (MF), and wide midfielder (WMF). In respect of acceleration profile, positional differences were found for all variables (p < 0.05), except average magnitude of accelerations (ACCAVG, p = 0.56) and decelerations (DECAVG, p = 0.76). The sprint profile also showed positional differences for all variables (p < 0.05), apart from sprint duration (p = 0.07). In addition, although low-intensity accelerations required significantly greater start speeds (Vo) than high-intensity accelerations in WMF (0.4 ± 0.2 km/h; p < 0.05) and FW (0.4 ± 0.2 km/h; p < 0.05), no significant differences (p > 0.05) were found in CD, FB, and MF. However, high-intensity decelerations were performed at significantly higher Vo than low-intensity decelerations in MF (2.65 ± 0.1 km/h; p < 0.05), FW (3.3 ± 0.1 km/h; p < 0.05), FB (3.9 ± 0.4 km/h; p < 0.05), WMF (4.3 ± 0.3 km/h; p < 0.05), and CD (4.1 ± 0.7 km/h; p < 0.05). Therefore, positional differences exist for most variables of the acceleration and sprint profiles. In addition, different Vo were observed between high-intensity and low-intensity accelerations as well as high-intensity and low-intensity decelerations.
#11 Reaction of the Organisms of Young Football Players to City Smog in the Sports Training
Reference: Int J Environ Res Public Health. 2020 Jul 30;17(15):E5510. doi: 10.3390/ijerph17155510.
Authors: Henryk Duda, Łukasz Rydzik, Wojciech Czarny, Wiesław Błach, Karol Görner, Tadeusz Ambroży
Download link: https://www.mdpi.com/1660-4601/17/15/5510/pdf
Summary: The essence of a sports training includes not only developing the skills necessary in a chosen sport but also particular care about athlete's health. This issue should be taken into account especially in case of children and youth engaged in sporting activities. In the paper there are issues connected to the control of physical effort abilities in the sports training of young football players and the assessment of the reaction of the body to physical exercise in city smog conditions (the environment of the city of Kraków) and clean air conditions (the environment of the town of Głuchołazy). This paper shows that, when assessing physical effort, one can consider not nly the results of physical tests but also the reaction of the body to a given physical load. One should remember that physical load depends not only on the methods used and the range of intensity, but also on the environmental conditions, like the quality of the air. Determining the reaction of the body to physical load (performance tests), taking into account the conditions in which the training takes place, prevents overloading and sets directions for rational sports training. The analysis of the results of the study leads to three main conclusions: (1) The planning of sports training has to consider not only the methods and means of the training but also environmental factors (air pollution); (2) Physical effort in smog conditions should be done with the use of antismog face masks; (3) The arrangement of sports training (particularly for youth) should strictly take into account the environment in which the training takes place.
#12 Effects of coordination training on the technical development in 10-13 years old football players
Reference: J Sports Med Phys Fitness. 2020 Jul 30. doi: 10.23736/S0022-4707.20.11270-2. Online ahead of print.
Authors: Mustafa Kösal, Gazanfer K GÜl, Murat Doğanay, Cristina Álvarez-García
Summary: The purpose of this study was to determine the effects of coordination training carried out by 10-13 years old male football players on the performance of dribbling, passing, shooting, ball bouncing and wall-volley skills. A total of 45 male football players were divided into three 15 participants groups. The experimental group performed 30 min coordination training three days a week for ten weeks while the control group one continued their routine training and control group two performed unstructured football training. Measurements included Mor and Christian, Yeagley and Johnson football skill tests. Pre- and post-test measurements were compared by an ANOVA 2 × 3. A significant level of P < 0.05 was established. All the skills, dribbling (P < 0.001), passing (P < 0.001), shooting (P < 0.001), ball bouncing (P = 0.047) and wall-volley (P < 0.001), improved after ten weeks in the experimental group, while only passing (P = 0.006), shooting (P = 0.007) and wall-volley (P< 0.001) improved in the control group one and none of the skills improved in the control group two (P > 0.05). The improvement was significant in the experimental group in comparison with the control groups (P < 0.001). The implementation of coordination exercises in combination with structured football training has been shown to be effective in improving general football ability among 10-13 male players.
The aim was to investigate the effects of sleep deprivation on soccer skills.
The aim was to investigate the relationship between motor development in adolescence and future adult performance.
Following studies were retrieved for this week:
#1 Injury Profiles in Korean Youth Soccer
Reference: Int J Environ Res Public Health. 2020 Jul 16;17(14):E5125. doi: 10.3390/ijerph17145125.
Authors: Inje Lee, Hee Seong Jeong, Sae Yong Lee
Download link: https://www.mdpi.com/1660-4601/17/14/5125/pdf
Summary: We aimed to analyze injury profiles and injury severity in Korean youth soccer players. Data on all injuries that occurred in U-15 youth soccer players during the 2019 season were collected from 681 players of 22 teams through a medical questionnaire. The questionnaire was based on injury surveillance procedures of the Federation International de Football Association Medical and Research Centre and International Olympic Committee, and it comprised questions on demographic characteristics, training conditions, and injury information. Among all players, defenders accounted for 33.0%, followed by attackers (30.7%), midfielders (26.8%), and goalkeepers (7.9%). Most players played soccer on artificial grounds (97.4%). Injuries occurred more frequently during training (56.3%) than during matches (43.7%). Recurrent injury rate was 4.4% and average days to return to full activities were 22.58. The ankle (26.6%) and knee joints (14.1%) were the most common injury locations, and ligament sprains (21.0%), contusions (15.6%), and fractures (13.9%) were the most frequent injury types. In conclusion, Korean youth soccer players have a high injury risk. Therefore, researchers and coaching staff need to consider these results as a key to prevent injuries in youth soccer players and injury prevention programs may help decrease injury rate by providing injury management.
#2 Salivary aldosterone and cortisone respond differently to high- and low-psychologically stressful soccer competitions
Reference: J Sports Sci. 2020 Jul 24;1-10. doi: 10.1080/02640414.2020.1796164. Online ahead of print.
Authors: Timothy S McHale, Wai-Chi Chee, Carolyn R Hodges-Simeon, David T Zava, Graham Albert, Ka-Chun Chan, Peter B Gray
Summary: Aldosterone and cortisone are released in response to physical and psychological stress. However, aldosterone and cortisone responses in children engaged in physical competition have not been described. We examined salivary aldosterone and salivary cortisone responses among Hong Kongese boys, aged 8-11 years, during (1) a soccer match against unknown competitors (N = 84, high psychological stress condition) and (2) an intrasquad soccer scrimmage against teammates (N = 81, low psychological stress condition). Aldosterone levels increased during the soccer match and intrasquad soccer scrimmage conditions, consistent with the view that aldosterone responds to physical stress. During the soccer match, winning competitors experienced larger increases in aldosterone compared to losing competitors, indicating that the degree of aldosterone increase was attenuated by match outcome. Cortisone increased during the soccer match and decreased during the intrasquad soccer scrimmage. Competitors on teams that resulted in a tie had larger cortisone increases compared to winners or losers. These findings highlight that the degree of cortisone change is related to boy's cognitive appraisal of the competitor type (i.e., teammates vs. unknown competitors) and the competitive nature of the game (e.g., tie). These results shed new light on adrenal hormone mediators of stress and competition during middle childhood.
#3 Z-score values of left ventricular dimensions in adolescent elite male soccer players
Reference: Eur J Pediatr. 2020 Jul 24. doi: 10.1007/s00431-020-03741-1. Online ahead of print.
Authors: Stephan Gerling, Tobias Pollinger , Holger Michel, Markus-Johann Dechant , Michael Melter , Werner Krutsch
Download link: https://link.springer.com/content/pdf/10.1007/s00431-020-03741-1.pdf
Summary: Recent studies showed contrasting findings in morphological changes due to competitive soccer in adolescent players (SP). We present a prospective study in 315 consecutive adolescent (10-14 years) male elite SP and 53 healthy matched active controls (CON). All participants underwent a complete transthoracic two-dimensional echocardiography (TTE). The mean age in SP was 12.8 ± 0.65 years compared to 12.6 ± 0.8 years in CON. For all left ventricular (LV) dimensions, mean Z-score values were higher in SP. There was a significant Z-score increase in interventricular septum diastolic diameter (2.47z vs. 1.62z, p < 0.05), left ventricular posterior wall diastolic and systolic diameter (1.15z vs. 0.47z, p < 0.05 and 1.05z vs. - 0.4z, p < 0.05). Athletes had significant greater LV mass indexed for BSA (94 ± 12 g/m2 vs. 81 ± 13 g/m2, p < 0.05). There was no significant difference in LV function or diameters. Conclusion: Our findings suggest that elite soccer training in adolescent male is a type of sport predominantly related to cardiac resistance remodeling. Adolescent SP may develop supernormal left ventricular wall dimensions (+ 2.0 to + 2.5z). If in SP Z-scores, any LV dimension above + 2.5 is measured, primary or secondary cardiomyopathies should be excluded. What is Known: • Morphological cardiac adaptation in response to exercise depends on the type, duration, and intensity of training. • Morphological and functional changes due to competitive sports (athlete's heart) occur even in pre-adolescent athletes. What is New: • Our findings point out that German elite soccer training in adolescent male (10-14 years of age) is a type of sport predominantly related to cardiac resistance remodeling. • If in an adolescent competitive soccer player any LV dimension Z-score value above + 2.5 is measured, a primary or secondary cardiomyopathy should be excluded.
#4 Player Experience During the Junior to Senior Transition in Professional Football: A Longitudinal Case Study
Reference: Front Psychol. 2020 Jul 9;11:1672. doi: 10.3389/fpsyg.2020.01672. eCollection 2020.
Authors: Scott C Swainston, Mark R Wilson, Martin I Jones
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7363945/pdf/fpsyg-11-01672.pdf
Summary: The purpose of this study was to explore the evolving perspectives of young players experiences going through the junior to senior transition in professional football. A primary objective was to adopt novel methods - weekly video diaries - to allow participants to control and report their own narratives as the transition unfolded over 40 weeks. Semi structured interviews, held at four time points, allowed the lead researcher to probe further on themes that were developing. Six participants from the academy volunteered to take part, but only the three who earned professional contracts completed the study. The primary themes in the academy were the pressure experienced waiting for the contract decision, and then preparation for senior football and the first team environment once contracts were awarded. Adaptation to senior football included not only increased physical and mental demands but also those related to the different style of play, the pressure to win, and how these both impacted decision-making. The football club set up two pathways to support this adaptation, loan moves and time with the U23's. In the following season, the move to the senior squad was characterized by a lack of opportunity to play for the first team, resulting in additional loan moves. These moves, and the associated perceived lack of support structures, led to the participants experiencing issues with their club identity, their motivation and their confidence. Internal (mindset) and external (social support) coping strategies were developed over the study's duration. Concluding comments from participants were related to greater acceptance of the need to be patient, perhaps reflecting on the club's reputation of giving young players a sound football education. These phases of the transition came with ups and downs for each participant illuminating key elements of the adaptation to senior competition, barriers to transition without early success, and social aspects of the transition. Enhanced detail to these key areas poses important questions for future research and applied practice.
#5 MRI and ultrasound criteria for the diagnosis of a sports hernia in football players
Reference: Wiad Lek. 2020;73(4):755-760.
Authors: Oleksandr Yu Ioffe , Natalia M Negria, Anastasiia V Omelchenko, Oleksandr P Stetsenko, Yuri A Dibrova, Mykola S Kryvopustov, Yuri P Tsiura, Tatiana V Tarasiuk
Summary: The aim of the study is to specify diagnostic MRI and ultrasound criteria for a sports hernia in order to verify its diagnosis in football players. The study included 50 professional and amateur football players aged 15 to 34 from 2016 to 2019. The criteria for inclusion in the study were: the presence of groin pain in football players, which prevented them from continuing to actively participate in sports activities. The findings of the study revealed that during MRI the two factors, which had the strongest influence, were "increased MR signal intensity on PDfs observed from the structures of the inguinal canal" and "increased MR signal intensity on PDfs observed from bone marrow of superior ramus of the pubic bone". During ultrasound of the inguinal area, the main criterion for a sports hernia diagnosis was "increased size of the inguinal canal". The verification of the diagnosis was carried out on the basis of the presence of a protrusion in the posterior wall of the inguinal canal. For a sports hernia diagnosis the MRI sensitivity is 91.67% (95% CI 77.5 - 98.2), specificity -78.57% (95% CI 49.2 - 95.3) and the sensitivity of ultrasound is 88.89% (95% CI 73.9 - 96.9), the specificity - 50% (95% CI 23.0 - 77). The combination of MRI and ultrasound makes it possible to accurately detect the presence of a sports hernia in the football player. Based on the findings of our study, we formulated MRI and ultrasound criteria for a sports hernia diagnosis.
#6 Influence of artificial turf temperature on physical performance and muscle contractile properties in football players after a repeated-sprint ability test
Reference: Sci Rep. 2020 Jul 29;10(1):12747. doi: 10.1038/s41598-020-69720-6.
Authors: Gabriel Calderón-Pellegrino, Leonor Gallardo, Víctor Paredes-Hernández, Jorge García-Unanue, Jesus Vicente Giménez, Enrique Colino, Jose Luis Felipe, Javier Sánchez-Sánchez
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7391762/pdf/41598_2020_Article_69720.pdf
Summary: This study aimed to analyse the effect of playing surface temperature on muscular and thermal response to a repeated-sprint ability (RSA) test in football players. Thirty-two male football players (23 ± 5 years; 1.77 ± 0.06 m; 71.2 ± 6.7 kg) from two squads of a third-division football club participated in the study. An RSA test was carried out at a high surface temperature (45.34 ± 2.53 °C) and low surface temperature (27.21 ± 2.17 °C). Before and after this test, the muscular response of the players was assessed through tensiomyography and thermograms. The results revealed that performance in the RSA test particularly increased at a higher surface temperature, especially in the first 5 m of the 30 m sprint test. While a reduction in maximal radial displacement (Dm) in the biceps femoris post-RSA was observed at lower surface temperatures, a higher temperature on the thigh, hamstring and calf was found in the higher surface temperature group. In conclusion, higher surface temperatures had an influence on players' thermal and tensiomyographic profile and improved performance in their repeated-sprint ability. These results suggest a need for coaches and players to be aware of these parameters to ensure adequate functionality and safety of the playing surface.
#7 Delayed ankle muscle reaction time in female amateur footballers after the first 15 min of a simulated prolonged football protocol
Reference: J Exp Orthop. 2020 Jul 25;7(1):54. doi: 10.1186/s40634-020-00275-1.
Authors: Daniel T P Fong, Wing-Ching Leung, Kam-Ming Mok, Patrick S H Yung
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7382667/pdf/40634_2020_Article_275.pdf
Summary: Ankle sprain injury rate is reported to be higher towards the end of a football match. Muscle fatigue may contribute to the delayed muscle reaction and subsequent injury. This study investigated the ankle muscle reaction time during a simulated, prolonged football protocol. Seven amateur female football players participated in a 105-min simulated, prolonged football protocol. An ankle muscle reaction test was conducted with a pair of ankle sprain simulators at a scheduled interval every 15-min. The reaction times of peroneus longus, tibialis anterior, and lateral gastrocnemius were collected using an electromyography system sampling at 1000 Hz. Repeated measures one-way multivariate analysis of variance with post-hoc paired t-tests were conducted to evaluate if the reaction time at each time point significantly differed from baseline. Statistical significance was set at p < 0.05 level. Reaction times started from 40.5-47.7 ms at baseline and increased to 48.6-55.7 ms at the end. Reaction times significantly increased in all muscles after the first 15 min except for the dominant lateral gastrocnemius. Increased reaction times were seen in the non-dominant limb after 60 min for tibialis anterior, after 75 min for peroneus longus, and after 90 min for the lateral gastrocnemius. Delayed reaction time of the ankle muscles were found after the first 15 min and in the final 45 min of a simulated prolonged football protocol. Strategies for injury prevention should also focus on tackling the delayed ankle muscle reaction time in the acute phase (the first 15 min), in addition to the latter minutes in the second half.
#8 Elite Football Coaches Experiences and Sensemaking about Being Fired: An Interpretative Phenomenological Analysis
Reference: Int J Environ Res Public Health. 2020 Jul 18;17(14):E5196. doi: 10.3390/ijerph17145196.
Authors: Marte Bentzen, Göran Kenttä, Pierre-Nicolas Lemyre
Download link: https://www.mdpi.com/1660-4601/17/14/5196/pdf
Summary: Chronic job insecurity seems to be a prominent feature within elite sport, where coaches work under pressure of dismissals if failing to meet performance expectations of stakeholders. The aim of the current study was to get a deeper understanding of elite football coaches' experiences of getting fired and how they made sense of that process. A qualitative design using semi-structured interviews was conducted with six elite football coaches who were fired within the same season. Interpretative phenomenological analysis was chosen as framework to analyze the data. The results reflected five emerging themes: Acceptance of having an insecure job, working for an unprofessional organization and management, micro-politics in the organization, unrealistic and changing performance expectation, and emotional responses. All coaches expressed awareness and acceptance regarding the risk of being fired. However, they experienced a lack of transparency and clear feedback regarding the causes of dismissal. This led to negative emotional reactions as the coaches experienced being evaluated by poorly defined expectations and by anonymous stakeholders. Sports organizations as employers should strive to be transparent during dismissal. In addition, job insecurity is a permanent stressor for coaches and should be acknowledged and targeted within coach education.
#9 Effectiveness of a Generic vs. Specific Program Training to Prevent the Short-Term Detraining on Repeated-Sprint Ability of Youth Soccer Players
Reference: J Strength Cond Res. 2020 Aug;34(8):2128-2135. doi: 10.1519/JSC.0000000000003670.
Authors: Alejandro Rodríguez-Fernández, José G Villa, Javier Sánchez-Sánchez, Jose A Rodríguez-Marroyo
Summary: The aim of this study was to analyze the effects of 2 short-term training programs to prevent the negative effect of detraining on repeated-sprint ability (RSA) performance. The study was performed during a 2-week midseason break without official matches. Forty-five youth soccer players (17.7 ± 0.8 years, 175.4 ± 5.5 cm, and 67.2 ± 5.1 kg) were split into 3 groups during the intervention period: inactivity group (IN; N = 16), generic high-intensity training group (GG; N = 15), and specific training group (SG; N = 14). IN was instructed to avoid performing physical activity during the 2-week training intervention. However, GG and SG performed 8 training sessions. GG performed a generic aerobic interval training consisting of 4 repetitions of 4 minutes of exercise at 90-95% of maximal heart rate. SG performed a specific conditioning through small-sided games (4 vs. 4, 4 × 4-minute) and repeated sprints (6 × 30-m). Testing sessions included an RSA test and a Yo-Yo intermittent recovery test level 1 (YYIR1). Repeated-sprint ability performance only improved after the training intervention in SG (∼2%, p < 0.01, (Equation is included in full-text article.)= 0.23-0.25). Both GG and IN declined their performance in post-test (∼2%, p < 0.01, (Equation is included in full-text article.)= 0.19-0.22). No significant effect, group × time, was analyzed for YYIR1 performance. This study suggests that only specific training, based on small-sided games and repeated sprints, leads to short-term improvements on RSA performance in youth soccer players.
#10 Basketball players possess a higher bone mineral density than matched non-athletes, swimming, soccer, and volleyball athletes: a systematic review and meta-analysis
Reference: Arch Osteoporos. 2020 Aug 5;15(1):123. doi: 10.1007/s11657-020-00803-7.
Authors: Emilija Stojanović, Dragan Radovanović, Vincent J Dalbo, Vladimir Jakovljević, Nenad Ponorac, Ricardo R Agostinete, Zdenek Svoboda, Aaron T Scanlan
Summary: Basketball athletes possess a higher bone mineral density (BMD) than matched non-athletes and swimming, soccer, and volleyball athletes. Differences appear to be exacerbated with continued training and competition beyond adolescence. The greater BMD in basketball athletes compared to non-athletes, swimming, and soccer athletes is more pronounced in males than females. The aim of this study was to examine differences in total and regional bone mineral density (BMD) between basketball athletes, non-athletes, and athletes competing in swimming, soccer, and volleyball, considering age and sex. PubMed, MEDLINE, ERIC, Google Scholar, and Science Direct were searched. Included studies consisted of basketball players and at least one group of non-athletes, swimming, soccer, or volleyball athletes. BMD data were meta-analyzed. Cohen's d effect sizes [95% confidence intervals (CI)] were interpreted as: trivial ≤ 0.20, small = 0.20-0.59, moderate = 0.60-1.19, large = 1.20-1.99, and very large ≥ 2.00. Basketball athletes exhibited significantly (p < 0.05) higher BMD compared to non-athletes (small-moderate effect in total-body: d = 1.06, CI 0.55, 1.56; spine: d = 0.67, CI 0.40, 0.93; lumbar spine: d = 0.96, CI 0.57, 1.35; upper limbs: d = 0.70, CI 0.29, 1.10; lower limbs: d = 1.14, CI 0.60, 1.68; pelvis: d = 1.16, CI 0.05, 2.26; trunk: d = 1.00, CI 0.65, 1.35; and femoral neck: d = 0.57, CI 0.16, 0.99), swimming athletes (moderate-very large effect in total-body: d = 1.33, CI 0.59, 2.08; spine: d = 1.04, CI 0.60, 1.48; upper limbs: d = 1.19, CI 0.16, 2.22; lower limbs: d = 2.76, CI 1.45, 4.06; pelvis d = 1.72, CI 0.63, 2.81; and trunk: d = 1.61, CI 1.19, 2.04), soccer athletes (small effect in total-body: d = 0.58, CI 0.18, 0.97), and volleyball athletes (small effect in total-body: d = 0.32, CI 0.00, 0.65; and pelvis: d = 0.48, CI 0.07, 0.88). Differences in total and regional BMD between groups increased with age and appeared greater in males than in females. Basketball athletes exhibit a greater BMD compared to non-athletes, as well as athletes involved in swimming, soccer, and volleyball.
The aim was to systematically review the predictive value of psychological talent predictors.
The study aimed to identify the differences in technical performance between players from clubs in UEFA Champions League matches.
Following studies were retrieved for this week:
#1 Utility of the anterior reach Y-BALANCE test as an injury risk screening tool in elite male youth soccer players
Reference: Phys Ther Sport. 2020 Jul 10;45:103-110. doi: 10.1016/j.ptsp.2020.06.002. Online ahead of print.
Authors: Paul J Read, Jon L Oliver, Gregory D Myer, Abdulaziz Farooq, Mark De Ste Croix, Rhodri S Lloyd
Summary: The aim was to examine growth and maturation trends in dynamic balance using the anterior reach Y-Balance test, and its utility as an injury risk screening tool. 346 players grouped as pre, circa or post peak height velocity (PHV) participated in this study. Pre-season anterior reach absolute and relative Y-Balance test scores and seasonal prospective lower extremity injury monitoring were used as outcome measures. Absolute reach distances were greatest post-PHV (p < 0.05). Relative to leg length, pre-PHV achieved the highest scores and increased between-limb differences. Significant associations between injury and anterior reach scores were present in pre (OR: 0.94, CI: 0.91-0.98, p < 0.05) and circa-PHV (OR: 1.05, 95% CI: 1.05-1.10, p < 0.05). Increased age (OR: 1.49, 95% CI: 1.04-2.13, p < 0.05) and height (OR: 1.06, 95% CI: 0.99-1.13, p = 0.82) were risk factors post-PHV. No differences in injury occurrence were shown between players with absolute reach difference >4 cm in any group. Anterior reach scores increased injury risk, but associations were small and inconsistent. The Y-Balance should be used with caution as a screening tool in this cohort.
#2 Competitive evaluation in male elite junior soccer players: entire match, replaced, and substitute players
Reference: J Exerc Rehabil. 2020 Jun 30;16(3):286-292. doi: 10.12965/jer.2040358.179. eCollection 2020 Jun.
Authors: Adriano Titton
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7365729/pdf/jer-16-3-286.pdf
Summary: The purpose of this study was to analyze the mood states, recovery, displacement patterns, and rating of perceived exertion of elite junior soccer players during a national competition, considering substitutions in the matches. Before the games, the mood states and total quality recovery (TQR) were evaluated. During the games, the total distance (TD), low-speed distance (LSD), and high-speed distance were monitored. At the end of the matches, the rating of perceived exertion scale was used. The average and standard deviation were used to compare the match stages, soccer positions and influence of the substitutions. The significance level adopted was 5%. In relation to the mood states, fatigue presented higher values (P<0.05) for entire match and substitute players, and in the TQR, substitute players presented better recovery (P<0.05) than entire match and replaced players. In the TD, shorter distances covered were observed (P<0.05) in the first half, and the average of the midfielders was longer (P<0.05) than that of the defenders. In the LSD, the midfielders covered longer distances (P<0.05) than the strikers and defenders. It is possible to conclude that the substitutions have an impact on the player positions, match stages and maintenance of the intensity of the players.
#3 Drug use and abuse and the risk of adverse events in soccer players: results from a survey in Italian second league players
Reference: Eur Ann Allergy Clin Immunol. 2020 Jul 30. doi: 10.23822/EurAnnACI.1764-1489.163. Online ahead of print.
Authors: F W Rossi, F Napolitano , V Pucino , G Capua , D Bianchedi , F Braconaro, A de Paulis
Download link: http://www.eurannallergyimm.com/cont/online-first/843/original-articlebrdrug-abuse-risk-adverse-events-soccer-3796allasp1.pdf
Summary: Drug use in athletes has been frequently investigated in the last three decades, especially regarding its misuse for doping. However little is known about the use of permitted drugs for medical purposes and less studies have investigated the relationship between adverse drugs reactions (ADRs) and sports. An observational cross-sectional investigation analyzing a group of second league soccer players (the second-highest division in Italy) was performed. Anamnestic and physical examinations as well as a validated questionnaire (AQUA©) were performed in a group of 378 Italian second league soccer players. Most players (91.8%) reported the use of NSAIDs in the previous year, and one third of them were regular users. Analgesics were used in 64% of the players, while 52.1% had taken antibiotics in the previous year. 29.20% of players used intraarticular treatments in the previous year. In 7,4% of players, an ADRs was reported: 3,47% reacted to NSAIDs, 2,6% to antibiotics, 1,05% to analgesics and 1 of them to supplements. For intra-articular injections, only 2 players experienced ADRs. One quarter of players experienced reactions as urticaria-angioedema syndrome or more severe conditions as bronchospasm or anaphylaxys. This study shows that drug misuse/abuse in soccer is a real matter of debate, especially with regards to NSAIDs, exposing athletes to predictable and/or unpredictable risks for their health.
#4 Variable long-term developmental trajectories of short sprint speed and jumping height in English Premier League academy soccer players: An applied case study
Reference: J Sports Sci. 2020 Jul 29;1-7. doi: 10.1080/02640414.2020.1792689. Online ahead of print.
Authors: Jason Moran, Kevin Paxton, Ben Jones, Urs Granacher, Gavin Rh Sandercock, Edward Hope, Rodrigo Ramirez-Campillo
Summary: Growth and maturation affect long term physical performance, making the appraisal of athletic ability difficult. We sought to longitudinally track youth soccer players to assess the developmental trajectory of athletic performance over a 6-year period in an English Premier League academy. Age-specific z-scores were calculated for sprint and jump performance from a sample of male youth soccer players (n = 140). A case study approach was used to analyse the longitudinal curves of the six players with the longest tenure. The trajectories of the sprint times of players 1 and 3 were characterised by a marked difference in respective performance levels up until peak height velocity (PHV) when player 1 achieved a substantial increase in sprint speed and player 3 experienced a large decrease. Player 5 was consistently a better performer than player 2 until PHV when the sprint and jump performance of the former markedly decreased and he was overtaken by the latter. Fluctuations in players' physical performance can occur quickly and in drastic fashion. Coaches must be aware that suppressed, or inflated, performance could be temporary and selection and deselection decisions should not be made based on information gathered over a short time period.
#5 School-based soccer practice is an effective strategy to improve cardiovascular and metabolic risk factors in overweight children
Reference: Prog Cardiovasc Dis. 2020 Jul 25;S0033-0620(20)30144-4. doi: 10.1016/j.pcad.2020.07.007. Online ahead of print.
Authors: André Seabra, João Brito, Pedro Figueiredo, Liliana Beirão, Ana Seabra, Maria José Carvalho, Sandra Abreu, Susana Vale, Augusto Pedretti, Henrique Nascimento, Luís Belo, Carla Rêgo
Summary: We examined the effects of a 6-month school-based soccer programme on cardiovascular (CV) and metabolic risk factors in overweight children. Methods: 40 boys [8-12 years; body mass index (BMI) >2 standard deviations of WHO reference values] participated in complementary school-based physical education classes (two sessions per week, 45-90 min each). The participants were divided into a soccer group (SG; n = 20) and a control group (CG; n = 20). The SG intervention involved 3 extra-curricular school-based soccer sessions per week, 60-90 min each. The intervention lasted for 6-months. All measurements were taken at baseline and after 6-months. From baseline to 6-months, the SG significantly improved (p < .05) BMI z-score, waist circumference, waist-to-height ratio, percentage of fat mass, percentage of fat-free mass, diastolic blood pressure, total cholesterol, triglycerides, low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol, but no such improvements were observed for the CG. After the intervention, the prevalence of soccer participants with normal waist-to-height ratio (30 vs. 5%; p = .037), systolic blood pressure (90 vs. 55%; p = .039), total cholesterol (80 vs. 65%; p = .035) and LDL-C (90 vs. 75%; p = .012) were significantly higher than at baseline. The findings suggest that a 6-month school-based soccer intervention program represents an effective strategy to reduce CV and metabolic risk factors in overweight children prepared to take part in a soccer program.
#6 Dribbling speed predicts goal-scoring success in a soccer training game
Reference: Scand J Med Sci Sports. 2020 Jul 27. doi: 10.1111/sms.13782. Online ahead of print.
Authors: Robbie S Wilson, Nicholas M A Smith, Nicolau Melo de Souza, Felipe Arruda Moura
Summary: The aim of this study was to explore the underlying bases of goal-scoring ability of junior soccer players. Male players (mean age 17.2 years, SD = 1.3) were recruited from an elite Brazilian football academy. We assessed each individual's dribbling and sprinting speed along five 30 m paths varying in curvature from 0 to 1.37 radians.m-1. We also quantified each player's ability to dribble the ball through a series of 15 cones using six different techniques. Dribbling, sprinting and technical dribbling were then compared with an individual's goal-scoring ability as assessed when competing against one defender and a goalkeeper protecting a full-sized goal (N = 20-48 attempts/ individual). Goal-scoring success was significantly positively associated with their sprint speed (r = 0.60; P = 0.014), dribbling speed (r = 0.81; P < 0.0001) and technical dribbling (r = 0.49; P = 0.022). An individual's percentage of shots saved was only significantly associated with their dribbling speed (r = -0.81; P < 0.001), with faster dribblers less likely to have their shots saved. Based on the full multivariate model for goal-scoring success (adjusted r2 = 0.60; P < 0.001), dribbling speed was the only significant correlate (t = 3.51; P < 0.001). Our study demonstrates that our metric of dribbling speed, as measured along curved paths, was associated with goal-scoring success. Future studies should focus on specific training regimes aimed at improving dribbling ability, and measuring any impact on the creation of goal-scoring opportunities and number of goals scored.
#7 Framing potential for adverse effects of repetitive subconcussive impacts in soccer in the context of athlete and non-athlete controls
Reference: Brain Imaging Behav. 2020 Jul 25. doi: 10.1007/s11682-020-00297-4. Online ahead of print.
Authors: Sara B Strauss, Roman Fleysher, Chloe Ifrah, Liane E Hunter, Kenny Ye, Richard B Lipton, Molly E Zimmerman, Mimi Kim, Walter F Stewart, Michael L Lipton
Summary: The benefits of athletic activity may be attenuated by sport-related head impacts, including soccer-related concussion and subconcussive events. The purpose of this study is to characterize the specific effects of soccer heading on white matter microstructure and cognitive function, independent of concussion, relative to non-athlete controls and relative to active athletes who are not involved in collision sports. 246 amateur soccer players, 72 non-contact/non-collision sports athletes and 110 healthy,non-athlete controls were included in the study, and underwent cognitive testing and 3T diffusion tensor imaging (DTI). Voxelwise linear regression, comparing soccer players and non-contact/non-collision sports athletes healthy,non-athlete controls, identified regions of abnormally low and high fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD) and mean diffusivity (MD) in athlete participants. Generalized estimating equations were used to examine the effects of 2 week and 1 year heading exposure quartile on cognitive performance and on the volume of each high and each low DTI parameter. Athletes with no or lower exposure to repetitive heading exhibited greater expression of low RD, greater expression of high FA and better performance on tasks of attention, processing speed, verbal memory, and working memory compared to non-athletes. Soccer players with the highest exposure to repetitive head impacts, however, did not differ significantly from healthy, non-athletes on either micro-structural features or cognitive performance, findings not explained by concussion history or demographic factors. These results are consistent with the notion that beneficial effects of athletic conditioning or training on brain structure and function may be attenuated by exposure to repeated subconcussive head impacts.
#8 A nutrition education intervention in adolescents who play soccer: The IDEHA-F project
Reference: Psicothema. 2020 Aug;32(3):359-365. doi: 10.7334/psicothema2019.394.
Authors: María M Fernández-Álvarez, Rubén Martín-Payo, Rebeca García-García, Marcelino Cuesta, Sergio Carrasco-Santos
Summary: Diet and physical activity are prioritised in behavioural interventions given their influence on major child health issues. The objective of this study was to assess the feasibility of an educational intervention, based on the Behaviour Change Wheel model, on adherence to healthy eating habits in adolescent soccer players in Asturias, Spain. This pilot study involved 319 soccer players (mean age=14.19 years; SD=1.089), who were distributed into a control group (CG) and an intervention group (IG). The response variables were: the usage rate of, adherence to, and acquisition of knowledge of the Mediterranean diet. The intervention included posters, a web-app, and practical activities. The mean score on the knowledge questionnaire was 2.53 for the CG and 3.42 for the IG (p <.001). A weak direct correlation was observed between diet knowledge and KIDMED scores (r =.222, p =.013). The total pre-test KIDMED (p <.001) and diet knowledge ( p =.05) scores explained approximately 33% of the total post-test KIDMED score. The combined use of posters and a web app as intervention tools have been shown to be feasible in order to provide information on healthy eating habits to adolescents who play soccer and to help them maintain those eating habits.
#9 A Longitudinal Analysis of the Executive Functions in High-Level Soccer Players
Reference: J Sport Exerc Psychol. 2020 Jul 25;1-9. doi: 10.1123/jsep.2019-0312. Online ahead of print.
Authors: Adam Beavan, Vincent Chin, Louise M Ryan, Jan Spielmann, Jan Mayer , Sabrina Skorski, Tim Meyer , Job Fransen
Summary: Assessments of executive functions (EFs) with varying levels of perceptual information or action fidelity are common talent-diagnostic tools in soccer, yet their validity still has to be established. Therefore, a longitudinal development of EFs in high-level players to understand their relationship with increased exposure to training is required. A total of 304 high-performing male youth soccer players (10-21 years old) in Germany were assessed across three seasons on various sport-specific and non-sport-specific cognitive functioning assessments. The posterior means (90% highest posterior density) of random slopes indicated that both abilities predominantly developed between 10 and 15 years of age. A plateau was apparent for domain-specific abilities during adolescence, whereas domain-generic abilities improved into young adulthood. The developmental trajectories of soccer players' EFs follow the general populations' despite long-term exposure to soccer-specific training and game play. This brings into question the relationship between high-level experience and EFs and renders including EFs in talent identification questionable.
#10 Assessment of diet quality and physical activity of soccer players aged 13 to 16, from the Principality of Asturias, Spain
Reference: An Pediatr (Barc). 2020 Jul 21;S1695-4033(20)30224-1. doi: 10.1016/j.anpedi.2020.05.024. Online ahead of print. [Article in Spanish]
Authors: María Del Mar Fernández-Álvarez, Rubén Martín-Payo, Edurne Zabaleta-Del-Olmo, Rebeca García-García, Marcelino Cuesta-Izquierdo, Xana González-Méndez
Summary: Diet and physical activity are factors that have key roles in childhood overweight and obesity prevention. Appropriate assessment of these factors is an essential task in public health. The main aims of the study are to assess body composition, physical activity, and adherence to Mediterranean diet of soccer players, aged 13 to 16 years old in Asturias, Spain. It also aims to evaluate the relationships between diet, physical activity, body composition, and personal characteristics. A cross-sectional descriptive survey approach was used involving children (n=303) with a mean age of 14.15 years (SD=1.06), and using the KIDMED and PAQ-A questionnaires to assess adherence to Mediterranean diet and level of physical activity, respectively. Body composition was represented using the participants' body mass index. Approximately 23.1% of the participants were overweight or obese. With regards to adherence to Mediterranean diet, 54.8% of the participants had medium adherence, while 8.9% had low adherence. PAQ-A mean score was 2.69 (SD=0.47). Excess weight was associated with being a goalkeeper (P=.001), higher PAQ-A (P=.011), and lower KIDMED scores (P=.032). Correlation analysis showed an inverse association between age and PAQ-A score (r=-0.122), and a direct association between KIDMED and PAQ-A scores (r=0.152). Participants had an adequate level of physical activity. However, they had an obesogenic profile similar to that of their age population, who were not soccer players. Actions to improve adherence to healthy diet practices are highly recommended.
#11 Effects of Match-Related Contextual Factors on Weekly Load Responses in Professional Brazilian Soccer Players
Reference: Int J Environ Res Public Health. 2020 Jul 17;17(14):E5163. doi: 10.3390/ijerph17145163.
Authors: Luiz Guilherme Cruz Gonçalves, Carlos Augusto Kalva-Filho, Fábio Yuzo Nakamura, Vincenzo Rago, José Afonso, Bruno Luiz de Souza Bedo , Rodrigo Aquino
Download link: https://www.mdpi.com/1660-4601/17/14/5163/pdf
Summary: This study aimed to quantify the weekly training load distributions according to match location, opponent standard, and match outcome in professional soccer players. Rate-of-perceived-exertion-based training load (sRPE) and distance- and accelerometry-based measures were monitored daily during 52 training sessions and 11 matches performed by 23 players. Athletes who played ≥ 60 min during non-congested weeks were considered for data analysis. The training days close to away matches (e.g., one day before the match = MD-1) presented greater sRPE, distance-based volume measures, and mechanical work (player load) compared to the training days close to home matches (p = 0.001-0.002; effect size (ES) = medium-large). The most distant days of the home matches (e.g., five days before the match = MD-5) presented higher internal and external loads than before away matches (p = 0.002-0.003, ES = medium). Higher sRPE, distance-based volume measures, and mechanical work were found during the middle of the week (e.g., three days before the match, MD-3) before playing against bottom vs. medium-ranking teams (p = 0.001-0.01, ES = small-medium). These metrics were lower in MD-5 before matches against bottom vs. medium-ranking opponents (p = 0.001, ES = medium). Higher values of all external load measures were observed during the training session before winning matches (MD-1) compared to a draw or loss (p < 0.001-0.001, ES = medium-large). In conclusion, the training load distribution throughout the week varied considerably according to match-contextual factors.
The aim of this study was to determine the role of FMS in the process of acquiring soccer-specific motor skills.
The study investigates the influence of specific soccer training with the non-dominant leg on mental rotation performance of young soccer players.
Following studies were retrieved for this week:
#1 Energy Requirements of Male Academy Soccer Players from the English Premier League
Reference: Med Sci Sports Exerc. 2020 Jul 21. doi: 10.1249/MSS.0000000000002443. Online ahead of print.
Authors: Marcus P Hannon, Lloyd J F Parker, Daniel J Carney, John McKeown, John R Speakman, Catherine Hambly, Barry Drust, Viswanath B Unnithan, Graeme L Close, James P Morton
Summary: The purpose was to inform the energy requirements of highly trained adolescent soccer players, total energy expenditure (TEE) was quantified in academy soccer players from the English Premier League (EPL). Twenty-four male adolescent soccer players from an EPL academy (n=8 U12/13; n=8 U15; n=8 U18) were assessed for baseline maturity (maturity offset), body composition (DXA) and resting metabolic rate (RMR; indirect calorimetry). Subsequently, TEE, energy intake (EI) and physical loading patterns were assessed over a 14-day in-season period using doubly labelled water, the remote food photographic method and global positioning system technology, respectively. Under-18 players presented with greater RMR (2236±93 kcal⋅day) and TEE (3586±487 kcal⋅day; range: 2542-5172 kcal⋅day) than both U15 (2023±162 and 3029±262 kcal⋅day, respectively; TEE range: 2738-3726 kcal⋅day) and U12/13 players (1892±211 and 2859±265 kcal⋅day, respectively; TEE range: 2275-3903 kcal⋅day) (all P<0.01), though no difference in TEE was apparent between the U12/13 and U15 age-groups. Fat-free mass was significantly different between all comparisons in a hierarchal manner (U18: 57.2±6.1 kg > U15: 42.9±5.8 kg > U12/13: 31.1±3.5 kg; all P<0.01). Within age-groups, no differences were apparent between EI and TEE (U12/13: -29±277 kcal⋅day, P=0.78; U15: -134±327 kcal⋅day, P=0.28; U18: -243±724 kcal⋅day, P=0.37), whilst U18 players (3180±279 kcal⋅day) reported higher EI than both U15 (2821±338 kcal⋅day; P=0.05) and U12/13 players (2659±187 kcal⋅day; P<0.01). The TEE of male academy soccer players progressively increase as players progress through the academy age-groups. In some individuals (evident in all age-groups), TEE was greater than that previously observed in adult EPL soccer players.
#2 Minimal Stabilization Time for Ultra-short Heart Rate Variability Measurements in Professional Soccer
Reference: Int J Sports Med. 2020 Jul 22. doi: 10.1055/a-1186-1316. Online ahead of print.
Authors: Francisco Forner-Llacer, Rodrigo Aranda-Malaves, Rafael Aranda Malavés, Julio Calleja-Gonzalez, Jose Antonio Perez-Turpin, Joaquin Gonzalez-Rodenas
Summary: The main aims of this study were: 1) to compare 1-minute RMSSD measurements using different stabilization times between them and also with the criterion; and 2) to determine the agreement between every 1-minute RMSSD measurement with the criterion in professional soccer players. Seven hundred eighteen HRV measurements from professional soccer players were taken. HRV was calculated from 5 to 10 minutes (criterion) and from 1-minute windows with different pre-stabilization times. Friedman and post-hoc tests were applied to compare 1-minute and criterion measurements. Effect size was considered to describe magnitude of change. To determine agreement, Spearman's correlation was applied, and Bland-Altman analysis was also done between each ultra-short HRV time window and the 5-minute HRV criterion period. The 1-minute HRV without any pre-stabilization time was the only one different from all the other 1-minute measurements that included 1 or more minutes of pre-stabilization (p<0.001). One-minute HRV measurements with 1 or more minutes of pre-stabilisation were highly correlated with those for the criterion period. One-minute HRV without pre-stabilization showed the lowest correlation and the highest bias from the criterion. It is concluded that 1-minute HRV measurements with a prior 1-minute or longer pre-stabilization time are valid to measure HRV in professional male soccer players.
#3 Mental health and suicide in former professional soccer players
Reference: J Neurol Neurosurg Psychiatry. 2020 Jul 21;jnnp-2020-323315. doi: 10.1136/jnnp-2020-323315. Online ahead of print.
Authors: Emma R Russell , Thomas McCabe, Daniel F Mackay, Katy Stewart, John A MacLean, Jill P Pell , William Stewart
Summary: There is growing recognition of an association between contact sports participation and increased risk of neurodegenerative disease, including Alzheimer's disease and chronic traumatic encephalopathy. In addition to cognitive impairment, a range of mental health disorders and suicidality are proposed as diagnostic features of traumatic encephalopathy syndrome, the putative clinical syndrome associated with chronic traumatic encephalopathy. However, to date, epidemiological data on contact sport participation and mental health outcomes are limited. For a cohort of former professional soccer players (n=7676) with known high neurodegenerative mortality and their matched general population controls (n=23 028), data on mental health outcomes were obtained by individual-level record linkage to national electronic records of hospital admissions and death certification. Compared with matched population controls, former professional soccer players showed lower risk of hospital admission for anxiety and stress related disorders, depression, drug use disorders, alcohol use disorders and bipolar and affective mood disorders. Among soccer players, there was no significant difference in risk of hospitalisation for mental health disorders between outfield players and goalkeepers. There was no significant difference in rate of death by suicide between soccer players and controls. Among a population of former professional soccer players with known high neurodegenerative disease mortality, hospital admissions for common mental health disorders were lower than population controls, with no difference in suicide. Our data provide support for the reappraisal of currently proposed diagnostic clinical criteria for traumatic encephalopathy syndrome, in particular the inclusion of mental health outcomes.
#4 Groin injury risk of pubertal soccer players increases during peak height velocity due to changes in movement techniques
Reference: J Sports Sci. 2020 Jul 21;1-9. doi: 10.1080/02640414.2020.1794769. Online ahead of print.
Authors: Thomas Dupré , Wolfgang Potthast
Summary: Adolescent athletes experience an increase in injury incidence when they undergo peak height velocity (PHV). To find the reason behind this increase, the present study investigated if PHV influences hip joint kinematics, kinetics and adductor muscle forces in two groups of adolescent soccer players performing 90°-cutting manoeuvres and inside passing. One group was estimated to be more than half a year before PHV (PRE, N = 12). The second group was estimated to be less than half a year before or after PHV (MID, N = 10). Maximum static gripping and adductor forces were measured. Motion capturing and inverse dynamics were used to calculate kinematics and kinetics. The MID group was significantly taller and heavier compared to PRE while the force measurements showed no differences. Statistics showed a higher hip abduction moment for MID during the cutting manoeuvre. Results from the anthropometrics and force measurements suggest that the moments of inertia of the participants' extremities increase faster than the muscles can adapt. A higher abduction moment of MID likely increases the load on the adductor muscles through a change of technique. Combining both findings, it is likely that the risk of suffering a groin injury is increased in the MID group.
#5 Landing Evaluation in Soccer Players with or without Anterior Cruciate Ligament Reconstruction
Reference: Int J Sports Med. 2020 Jul 20. doi: 10.1055/a-1171-1900. Online ahead of print.
Authors: Ahmad Alanazi, Katy Mitchell, Toni Roddey, Aqeel Alenazi, Msaad Alzhrani, Alexis Ortiz
Summary: The purpose of this study was to evaluate landing biomechanics in soccer players following ACLR during two landing tasks. Eighteen soccer players with an ACLR and 18 sex-matched healthy control soccer players participated in the study. Planned landing included jumping forward and landing on the force-plates, whereas unplanned landing included jumping forward to head a soccer ball and landing on the force-plates. A significant landing×group interaction was found only for knee flexion angles (p=0.002). Follow-up comparisons showed that the ACL group landed with greater knee flexion during planned landing compared with unplanned landing (p<0.001). Significant main effects of landing were found. The unplanned landing showed reduction in hip flexion (p<0.001), hip extension moments (p<0.013), knee extension moments (p<0.001), and peak pressure (p<0.001). A significant main effect for group for gastrocnemius muscle was found showing that the ACL group landed with reduced gastrocnemius activity (p=0.002). Unplanned landing showed greater injury predisposing factors compared with planned landing. The ACL group showed nearly similar landing biomechanics to the control group during both landing tasks. However, the ACL group used a protective landing strategy by reducing gastrocnemius activity.
#6 Individual Response to External Training Load in Elite Football Players
Reference: Int J Sports Physiol Perform. 2020 Jan 30;15(5):696-704. doi: 10.1123/ijspp.2019-0453.
Authors: Håvard Wiig, Thor Einar Andersen, Live S Luteberget, Matt Spencer
Summary: The purpose was to investigate within-player effect, between-player effect, and individual response of external training load from player tracking devices on session rating of perceived exertion training load (sRPE-TL) in elite football players. The authors collected sRPE-TL from 18 outfield players in 21 training sessions. Total distance, high-speed running distance (>14.4 m/s), very high-speed running distance (>19.8 m/s), PlayerLoad™, PlayerLoad2D™, and high-intensity events (HIE > 1.5, HIE > 2.5, and HIE > 3.5 m/s) were extracted from the tracking devices. The authors modeled within-player and between-player effects of single external load variables on sRPE-TL, and multiple levels of variability, using a linear mixed model. The effect of 2 SDs of external load on sRPE-TL was evaluated with magnitude-based inferences. Total distance, PlayerLoad™, PlayerLoad2D™, and HIE > 1.5 had most likely substantial within-player effects on sRPE-TL (100%-106%, very large effect sizes). Moreover, the authors observed likely substantial between-player effects (12%-19%, small to moderate effect sizes) from the majority of the external load variables and likely to very likely substantial individual responses of PlayerLoad™, high-speed running distance, very high-speed running distance, and HIE > 1.5 (19%-30% coefficient of variation, moderate to large effect sizes). Finally, sRPE-TL showed large to very large between-session variability with all external load variables. External load variables with low intensity-thresholds had the strongest relationship with sRPE-TL. Furthermore, the between-player effect of external load and the individual response to external load advocate for monitoring sRPE-TL in addition to external load. Finally, the large between-session variability in sRPE-TL demonstrates that substantial amounts of sRPE-TL in training sessions are not explained by single external load variables.
#7 Females Sustain more Ankle Injuries than Males in Youth Football
Reference: Int J Sports Med. 2020 Jul 20. doi: 10.1055/a-1192-5399. Online ahead of print.
Authors: Taru Sokka, Matias Hilska, Tommi Vasankari, Mari Leppänen, Pekka Kannus, Jari Parkkari, Heidi Haapasalo, Hannele Forsman, Jani Raitanen, Kati Pasanen
Summary: This prospective study evaluated the incidence and pattern of acute injuries in youth (9- to 14-year- old) football players. Ten football clubs [n=730 players (567 males, 163 females)] participated in the 20-week follow-up study (January-June 2015). Data was collected by sending a standardized weekly SMS to players' parents/guardians with follow-up interviews for injured players. During the study period, 278 players (38%) sustained 410 acute injuries. The overall injury incidence for males and females was 6.47 (95% CI, 5.84-7.09) injuries per 1000 h of football exposure. Most injuries (40%) caused minimal absence from sports. Eighty-four percent of the injuries affected the lower extremities, with the ankle (30%), knee (17%), and thigh (16%) being the most commonly injured body sites. Females had significantly higher ankle injury rate (IRR) 1.85 (95% CI, 1.18-2.91, p=0.007) and non-contact ankle injury rate IRR 2.78 (95% CI, 1.91-4.02, p<0.001) than males. In conclusion, our results showed that the acute injury incidence among youth football is moderately high, and females are at higher risk for ankle injuries. Injury prevention programs aimed at preventing ankle injuries should be considered in the future.
#8 Homogeneous Distribution of Passing between Players of a Team Predicts Attempts to Shoot at Goal in Association Football: A Case Study with 10 Matches
Reference: Nonlinear Dynamics Psychol Life Sci. 2020 Jul;24(3):353-365.
Authors: Jose Gama , Goncalo Dias, Pedro Passos, Micael Couceiro, Keith Davids
Summary: This paper presents a case study which aims to establish a relationship between the homogeneity of passing distribution between players of a team and goal attempts in the team sport of association football. We observed data from 10 competitive football matches, involving 10 different professional football teams of different performance levels, competing in the Portuguese League during the 2010/2011 season. Performance data were analysed using the Match Analysis Software Amisco. Shannon's entropy measure was used to quantify the homogeneity of passing distribution within each team. Results suggested the existence of a pattern between an increase in the homogeneity of passing distributions and the attempts to scoring goals in the sample of competitive matches studied. A homogeneous distribution of passes can moderately predict (approximately 45% of accuracy) when a goal attempt will occur within the following minute of an entropy assessment.
#9 Effects of two exercise programmes on joint position sense, dynamic balance and countermovement jump in male amateur football players. A randomised controlled trial
Reference: J Sports Sci. 2020 Jul 20;1-11. doi: 10.1080/02640414.2020.1794472. Online ahead of print.
Authors: Marcos J Navarro-Santana, Iván Asín-Izquierdo, Guido F Gómez-Chiguano, Daniel Albert-Lucena, Gustavo Plaza-Manzano, Ángel Pérez-Silvestre
Summary: The injury prevention and warm-up exercises programmes improve physical performance and injury ratio, but it is poorly investigated in amateur football. The aim was to assess the effects of two warm-up multi-station programmes (IAI-Programme and FIFA11+) through JPS, LSDT and CMJ. Study design: Randomised controlled trial. 36 football players were randomised into 2 groups: IAI-Programme (n = 18) and FIFA11+ (n = 18) and performed the intervention protocol for 6 weeks. JPS, LSDT and CMJ were measured at baseline, after 6, 10 and 18 weeks (from baseline). The inter-group and intra-group differences were assessed by repeated-measures analysis of variance test (ANOVA). Significant differences between groups were found after 18 weeks in the absolute angular error (-2.18[-4.33,-0.047], d = 0.69, p < 0.05) of the JPS and in the CMJ (p = 0.001, ŋ2p=,0.298) in favour of IAI-Programme when compared to FIFA11 +. No significant differences between groups were found in the LSDT. There were also intra-group differences observed in the LSDT in both groups. IAI-Programme can provide sensitive benefits with respect to the proprioceptive ability of knee flexion and CMJ than FIFA11 +. Both IAI-Programme and FIFA11+ present improvements in the dynamic postural control measured by the LSDT.
#10 Performing Soccer-Specific Training With Blood Flow Restriction Enhances Physical Capacities in Youth Soccer Players
Reference: J Strength Cond Res. 2020 Jul 23. doi: 10.1519/JSC.0000000000003737. Online ahead of print.
Authors: Seyed A Hosseini Kakhak, Mojtaba Kianigul, Amir-Hossein Haghighi, Mehdi Jabbari Nooghabi, Brendan R Scott
Summary: This study investigated the effect of soccer training with blood flow restriction (BFR) on physical performance in youth athletes. Nineteen semiprofessional soccer players were randomly assigned to either normal soccer training (ST; n = 9) or soccer training with BFR (STBFR; n = 10). Both groups performed identical activities during a 6-week preseason training phase, either with or without lower limb BFR. Training included soccer-specific drills, small-sided games, plyometrics, and continuous running. Before and after the intervention, players were assessed for leg extension strength and endurance, countermovement jump performance, 40-yd sprint time, change-of-direction (COD) ability, aerobic endurance, and soccer-specific endurance (while dribbling a ball). Significantly larger improvements were observed in the STBFR compared with the ST group for tests of muscular endurance (74.8 ± 34.1% vs. 4.0 ± 14.6%), COD (8.1 ± 3.7% vs. 2.8 ± 4.7%), and aerobic (54.1 ± 19.6% vs. 24.7 ± 27.2%) and soccer-specific endurance (58.4 ± 19.6% vs. 22.7 ± 10.2%). Main effects for time were observed for maximal strength, jumping, and sprinting performance (p < 0.001) but with no group and time interaction. These findings demonstrate that team sport training with BFR can enhance physical qualities that are related to performance in youth soccer players. This application of BFR may improve the adaptive responses of muscles, without having to dedicate additional training time to muscular qualities.
#11 Assessing the Anthropometric Profile of Spanish Elite Reserve Soccer Players by Playing Position over a Decade
Reference: Int J Environ Res Public Health. 2020 Jul 28;17(15):E5446. doi: 10.3390/ijerph17155446.
Authors: Jon Manuel Vega, Asier Gonzalez-Artetxe, Jon Ander Aguinaco, Asier Los Arcos
Download link: https://www.mdpi.com/1660-4601/17/15/5446/pdf
Summary: The aims of this study were to describe the evolution of the anthropometric profile of soccer players over a decade and to compare the anthropometric profiles of players promoted from an elite reserve team to high-level soccer with those players who were not promoted. We examined the body mass, height, body-mass index, and body fat of 98 players enrolled in the reserve team from 2008 to 2018. The players were classified in terms of (a) the highest competitive level they achieved up to the 2019/2020 season (i.e., Spanish 1st-2nd divisions or semi-professional); (b) the period in which they played their last season on the team; and (c) their playing position. Over time, the height of goalkeepers, lateral midfielders, and attackers has increased (effect size = 0.66 ± 1.13) but has decreased in central midfielders (effect size = 0.83). The body fat of defenders has also fallen (effect size = 0.55 ± 0.95). Spanish high-level goalkeepers, lateral midfielders, and attackers were taller than their semi-professional player counterparts (effect size = 1.20 ± 1.98). Body fat did not determine promotion from a reserve team to high-level soccer, but height may be an advantage for several playing positions. The assessment of the anthropometric profile and the application of interventions should be designed according to the playing position.
The aim of the study was to explore the underlying bases of goal-scoring ability of young soccer players.
The aim of the present study was to examine the relationship between basics cognitive functions and sports-specific motor skills in elite youth soccer players
The aim was to examine the contribution of maturity status and body size descriptors to age-associated inter-individual variability in VO2peak and to present static allometric models to normalize in male youth soccer players.
The aim of this study was to determine the optimal recovery time to elicit PAP after a bout of high-intensity resistance exercise in professional soccer players.
Following studies were retrieved for this week:
#1 Performance changes during the off-season period in football players - Effects of age and previous hamstring injury
Reference: J Sports Sci. 2020 Jul 13;1-11. doi: 10.1080/02640414.2020.1792160. Online ahead of print.
Authors: Jordi Vicens-Bordas, Ernest Esteve, Azahara Fort-Vanmeerhaeghe, Martí Casals, Thomas Bandholm, Lasse Ishøi, David Opar, Anthony Shield, Kristian Thorborg
Summary: The aims of this study were to investigate changes in selected performance measures during an off-season period, their association, and the potential role of age and previous hamstring injury in semi-professional and amateur football players. Seventy-four male players (age: 25 ± 4 years, stature: 178.0 ± 6.6 cm, body mass: 74.9 ± 8.1 kg) were assessed at the beginning and end of the off-season summer-period for sprint, change-of-direction performance and eccentric hamstring strength. Small to medium increases in sprint times were observed at 5 (d = 0.26, p = 0.057), 10 (d = 0.42, p < 0.001) and 30 m (d = 0.64, p < 0.001). Small (d = -0.23, p = 0.033) improvements were observed for COD performance, and no changes in eccentric hamstring strength (d = 0.10, p = 0.317). The changes in the outcomes were not affected by age (p = 0.449 to 0.928) or previous hamstring injury (p = 0.109 to 0.995). The impaired sprint performance was not related to changes in eccentric hamstring strength (r = -0.21 to 0.03, p = 0.213 to 0.856), instead, changes in COD performance were associated with changes in eccentric hamstring strength (r = -0.42, p = 0.008).
#2 Tattoos among professional football players in the 2018-2019 Spanish La Liga season
Reference: Ann Dermatol Venereol. 2020 Jul 9;S0151-9638(20)30249-0.
doi: 10.1016/j.annder.2020.03.008. Online ahead of print.
Authors: N Kluger , R Ahava
Summary: Data regarding tattoos among football players are limited. We investigated the prevalence and characteristics of tattoos among elite players over a full season in the Spanish La Liga. We assessed whether tattoos had any impact on the performance and behavior of players and teams on the pitch. Demographic (age, geographic origin, position), performance (goal-scoring) and disciplinary data (yellow/red cards received) for 476 players and overall team statistics over the 2018-2019 season were analyzed according to the presence of visible tattoos (head and neck, upper arms, lower limbs) for each player. Of the 472 players analyzed, 160 (36%) had visible tattoos (upper limbs, 99%; lower limbs, 18.5%; head and neck, 12%), most of which were in black ink (83%). Players from South and Central America had the highest prevalence of visible tattoos (50%) and significantly more head and neck tattoos than Europeans (19% vs. 10% P=0.02). Tattoos were not significantly related to players' age or position. The mean number of goals scored was higher in the tattooed player group (2.7±4.6 goals vs. 1.9±3.3; P=0.013). There was a correlation between having tattoos and number of goals (Spearman rho 0.103, P=0.034). Tattooed players were more likely to have received≥1 yellow card (91% vs. 83.5%, P=0.03). There was no difference regarding red cards received (15 vs. 14%, P>0.05). The mean number of yellow cards was higher among players with tattoos than those without (4.4±3.2 vs. 3.6±3.2; P=0.01). However, the proportion of tattooed players in a team did not influence the overall team outcomes. The results were no longer significant when we included only players taking part in at least in 22 matches. Among footballers in La Liga, 36% had visible tattoos, with individual variations attributable to differences in geographic, social, cultural and religious background. Having tattoos was associated with certain aspects of individual performance and discipline. The question whether this factor should be taken into consideration by players' agents and team managers remains open.
#3 Systematic Reductions in Differential Ratings of Perceived Exertion Across a 2-Week Repeated-Sprint-Training Intervention That Improved Soccer Players' High-Speed-Running Abilities
Reference: Int J Sports Physiol Perform. 2020 May 6;1-8. doi: 10.1123/ijspp.2019-0568. Online ahead of print.
Authors: Shaun J McLaren, Jonathan M Taylor, Tom W Macpherson, Iain R Spears, Matthew Weston
Summary: The purpose was to quantify changes in differential ratings of perceived exertion (dRPE) across a 2-wk repeated-sprint-training intervention that improved high-intensity intermittent-running ability and linear speed of semiprofessional soccer players. Thirteen players completed 3 (sessions 1-3) or 4 (sessions 4-6) sets of 7 sprints (group 1 [n = 7]: 30-m straight; group 2 [n = 6]: 2 × 10-m shuttle), with 20 s and 4 min of recovery between sprints and sets, respectively. Postset perceptions of breathlessness (RPE-B) and leg-muscle exertion (RPE-L) were rated using the CR100 scale. Overall, RPE-B (mean [SD]: 46  arbitrary units [AU], "hard") was most likely higher than RPE-L (39  AU, "somewhat hard," mean difference: 8 AU; 90% confidence limits [CLs]: ±2). Set-to-set increases in dRPE (in AU; 90% CL: approximately ±2) were large in session 1 (RPE-B: 15; RPE-L: 14), moderate in sessions 2-5 (RPE-B: 7-10; RPE-L: 7-8), and small (RPE-B: 6) to moderate (RPE-L: 7) in session 6. Across the intervention, RPE-B reduced moderately in sets 3 (-13; 90% CL: ±4) and 4 (-12; 90% CL: ±12) and RPE-L reduced by a small magnitude in set 3 (-5; 90% CL: ±6). The set 4 change in RPE-L was unclear (-11; 90% CL: ±13). The authors observed systematic intrasession and intersession changes in dRPE across a 2-wk repeated-sprint-training intervention, with a fixed prescription of external load that improved semiprofessional soccer players' high-speed-running abilities. These findings could support dRPE as a measure of internal load and highlight its usefulness in evaluating repeated-sprint-training dose-response.
#4 The influence of thermal stress on the physical and technical activities of soccer players: lessons from the 2018 FIFA World Cup in Russia
Reference: Int J Biometeorol. 2020 Jul 16. doi: 10.1007/s00484-020-01964-3. Online ahead of print.
Authors: Marek Konefał, Paweł Chmura, Michał Zacharko, Jarosław Baranowski, Marcin Andrzejewski, Krzysztof Błażejczyk, Jan Chmura
Download link: https://link.springer.com/content/pdf/10.1007/s00484-020-01964-3.pdf
Summary: The present study attempts to assess changes in soccer players' physical and technical activity profiles due to thermal stress, measured with the Universal Thermal Climate Index (UTCI), in training centres and during matches of the 2018 FIFA World Cup in Russia. The study also verifies the theoretical models of soccer players' physiological parameters. The study sample consisted of 945 observations of 340 players of national teams taking part in the World Cup in Russia. The measured variables included physical activities: total distance covered, distances covered with an intensity of 20-25 km/h, number of sprints; technical activities: number of shots, number of passes, pass accuracy and physiological indicators: evaporative water loss and heart rate. In addition, the final ranking places of each national team were also used in the study. The UTCI was calculated based on meteorological data recorded at training centres and during matches. The UTCI records were then classified into two ranges: NTS-no thermal stress (UTCI 9-26 °C) and TS-thermal stress (UTCI > 26 °C). Climatic conditions at soccer training centres assessed as involving "no thermal stress" are found to be more beneficial for increasing the total distance covered and the number of sprints performed by players during a match. The theoretical models for determining soccer players' physiological parameters used in the study reduce the players' heart rate effort and evaporative water loss, which is in line with findings in studies by other authors. The climatic conditions at soccer training centres and during tournament matches should be taken into account in planning preparations for future World Cup tournaments, especially those in hotter countries.
#5 Multidirectional sprints in soccer: are there connections between linear, curved, and change-of-direction speed performances?
Reference: J Sports Med Phys Fitness. 2020 Jun 16. doi: 10.23736/S0022-4707.20.11155-1. Online ahead of print.
Authors: Tomás T Freitas, Ian Jeffreys , Valter P Reis , Victor Fernandes, Pedro E Alcaraz, Lucas A Pereira, Irineu Loturco
Summary: The aim of this study was to investigate the relationships between linear sprint, curve sprint (CS), and change of direction (COD) abilities and vertical jump performance in elite young soccer players. Twenty-nine players from the same soccer club participated in this study. On the same day, athletes performed countermovement jump (CMJ), 17-m linear sprint (with a 10- m split time), CS (for both sides), and COD tests. A Pearson product moment correlation was performed to determine the associations between the assessed variables. Significance level was set at P< 0.05. Linear sprint was significantly related to CS (r ranging from 0.67 and 0.76; P< 0.05) but not to COD performance (r = 0.23 and 0.33 for 10- and 17-m, respectively; P> 0.05). CS ability (for both good and weak sides) was significantly associated with COD performance (r = 0.60 and 0.54, respectively; P< 0.05). CMJ height was significantly correlated with both linear and CS velocities (r varying between 0.50 and 0.68; P< 0.05), but not with COD velocity (r =0.37; P> 0.05). Based on these findings, it is possible to suggest that training strategies designed to improve vertical jumping capacity may potentially improve both linear and curvilinear sprint abilities. Moreover, increases in COD velocity may also produce positive changes in CS performance.
#6 The effects of soccer training in aerobic capacity between trained and untrained adolescent boys of the same biological age
Reference: J Sports Med Phys Fitness. 2020 Jul 16. doi: 10.23736/S0022-4707.20.11117-4. Online ahead of print.
Authors: Athanasios Mandroukas, Thomas I Metaxas, Yiannis Michailidis, Kosmas Christoulas, Jan Heller
Summary: The purpose of this study was to examine the effects of soccer training on maximal oxygen uptake and anthropometric characteristics in different ages of soccer players and untrained adolescents of the same biological age. A total of one hundred and twenty six (n=126) young soccer players and untrained boys throughout the developmental ages of 12 (soccer players n=22; untrained boys=22) 14 (soccer players n=20; untrained boys= 18) and 16 (soccer players n=22; untrained boys=22) volunteered to participate in the study. Sexual maturation was classified according to Tanner's stages. Soccer players participated both in their school's physical education program and in a soccer training program, while the untrained participated only in their school's physical education program. All participants underwent anthropometric measurements and performed a maximal exercise test on a motor driven treadmill to determine maximal oxygen uptake (V̇O2max) and cardiorespiratory indices. Blood lactate (BL) concentration was determined in the 5th minute of recovery using a lactate photometer. The trained group showed significantly higher VO2max, in absolute and relative values (P<0.001), BLmax (P<0.05) and maximal respiratory exchange ratio (RERmax) (P<0.05) compared to the untrained group. Resting heart rate (HR) and systolic blood pressure were significantly lower (P<0.05) for the trained compared to untrained. The results of this study showed that systematic soccer training has a positive effect in the central cardiovascular system expressed as VO2max, HR and blood pressure.
#7 Peak torque angle, acceleration time and time to peak torque as additional parameters extracted from isokinetic test in professional soccer players: a cross-sectional study
Reference: Sports Biomech. 2020 Jul 16;1-12. doi: 10.1080/14763141.2020.1784260. Online ahead of print.
Authors: Daniel Germano Maciel, Glauko André Figueiredo Dantas, Mikhail Santos Cerqueira, Jean Artur Mendonça Barboza, Vinícius Vieira De Alencar Caldas, Alef Cavalcanti Matias de Barros, Ronan Romeno Varela, Diego Helps Magalhães, Wouber Hérickson de Brito Vieira
Summary: This study investigated additional and traditional variables from isokinetic test of thigh muscles in soccer players across different field positions. One hundred and eighty-nine athletes performed maximal concentric isokinetic knee contractions on dominant (DL) and non-dominant limb (NDL) at 60º/s and 240º/s. The additional outcomes peak torque angle (AngPT), acceleration time (AcT) and time to peak torque (TPT) and traditional outcomes Peak torque (PT), total work (TW) and power (Pw) were extracted from the exam. Goalkeepers (GK), side backs (SB), central backs (CB), central defender midfielders (CDM), central attacking midfielders (CAM) and forwards (FW) were considered. Comparisons between limbs and positions demonstrated that SB extensors of the DL presented TPT lower (p = 0.006) and AngPT higher (p = 0.011) than NDL at 60°/s. CDM extensors of the DL showed lower TPT at 60°/s (p = 0.003) and 240°/s (p = 0.024). CAM flexors of the DL showed lower TPT (p = 0.026) and AcT (p = 0.021) at 240°/s than NDL. CB, CDM and CAM extensors of the NDL showed higher PT, TW and Pw than DL (p < 0.05). In conclusion, there are muscle imbalances between limbs in SB, CDM and CAM and across different field positions.
#8 Walking Soccer: A Systematic Review of a Modified Sport
Reference: Scand J Med Sci Sports. 2020 Jul 15. doi: 10.1111/sms.13772. Online ahead of print.
Authors: Rekesh Corepal, Jia Yu Zhang, Sanya Grover, Harry Hubball, Maureen C Ashe
Summary: Walking soccer (football) is an emerging modified sport gaining recognition globally. The aim was to synthesize current evidence for walking soccer, and provide a summary of global walking soccer organizations. We searched for studies published across all years and all languages within multiple databases for studies focused on walking soccer (football) in adults (18+ years). Two authors independently screened citations at Level 1 and 2. We also conducted a forward citation search and reviewed the reference lists for included studies. We searched the grey literature to identify walking soccer organizations. We conducted the last database search in December 2019. We conducted a standard systematic review following established guidelines. We also summarized findings from a limited search for walking soccer organizations. For peer-reviewed literature, we used the Mixed Methods Appraisal Tool (MMAT) to assess methodological quality, and conducted a narrative synthesis of the evidence. We identified nine peer-reviewed studies (with 117 participants). Most studies included small sample sizes and interventions with short duration. Walking soccer is an emerging modified sport that is popular across the United Kingdom (UK), with its reach extending to other countries. Limited published evidence exists for walking soccer, despite is global popularity. For the studies identified, generalizability was limited to predominately older men from the UK. Based on preliminary findings, walking soccer has the potential to confer health benefits and build social connections.
#9 Individual versus team heart rate variability responsiveness analyses in a national soccer team during training camps
Reference: Sci Rep. 2020 Jul 16;10(1):11726. doi: 10.1038/s41598-020-68698-5.
Authors: Alejandro Muñoz-López , José Naranjo-Orellana
Download link: https://www.nature.com/articles/s41598-020-68698-5.pdf
Summary: Heart rate variability (HRV) analyses can be performed using group or individual changes. Individual changes could be of potential interest during training camps for national soccer teams. The purpose of this study was to compare whether analysis of individual daily HRV could detect changes in cardiac autonomic responses during training camps for national soccer teams. During two different training camps, 34 professional soccer players were monitored daily over 9 days, using heart rate monitors. Players were divided into First Eleven (those who participated in the main squad) or Reserves. Daily HRV was individually analyzed using a day-to-day method or a baseline (days prior to first match) method, using the smallest worthwhile change and the typical error in the estimate to establish a trivial (random change) zone. Group changes were also analyzed using an ANOVA one-way repeated measures test. Players' responsiveness was classified as High-, Low- or Non-response depending on individual changes. Both analyses showed substantial daily individual changes after playing a soccer match, regardless of the group. However, group changes showed that only First Eleven players had significant changes after playing a soccer match. In conclusion, individual daily HRV analyses are useful in detecting individual changes in professional soccer players.
#10 Prevalence and Incidence of Microhemorrhages in Adolescent Football Players
Reference: AJNR Am J Neuroradiol. 2020 Jul;41(7):1263-1268.
Authors: B R Shah, J M Holcomb, E M Davenport, C M Lack, J M McDaniel, D M Imphean, Y Xi, D A Rosenbaum, J E Urban, B C Wagner, A K Powers, C T Whitlow, J D Stitzel, J A Maldjian
Summary: SWI is an advanced imaging modality that is especially useful in cerebral microhemorrhage detection. Such microhemorrhages have been identified in adult contact sport athletes, and the sequelae of these focal bleeds are thought to contribute to neurodegeneration. The purpose of this study was to utilize SWI to determine whether the prevalence and incidence of microhemorrhages in adolescent football players are significantly greater than those of adolescent noncontact athletes. Preseason and postseason SWI was performed and evaluated on 78 adolescent football players. SWI was also performed on 27 adolescent athletes who reported no contact sport history. Two separate one-tailed Fisher exact tests were performed to determine whether the prevalence and incidence of microhemorrhages in adolescent football players are greater than those of noncontact athlete controls. Microhemorrhages were observed in 12 football players. No microhemorrhages were observed in any controls. Adolescent football players demonstrated a significantly greater prevalence of microhemorrhages than adolescent noncontact controls (P = .02). Although 2 football players developed new microhemorrhages during the season, microhemorrhage incidence during 1 football season was not statistically greater in the football population than in noncontact control athletes (P = .55). Adolescent football players have a greater prevalence of microhemorrhages compared with adolescent athletes who have never engaged in contact sports. While microhemorrhage incidence during 1 season is not significantly greater in adolescent football players compared to adolescent controls, there is a temporal association between playing football and the appearance of new microhemorrhages.
#11 Soccer Heading and Subclinical Neuropsychiatric Symptomatology in Professional Soccer Players
Reference: Neurology. 2020 Jul 10;10.1212/WNL.0000000000010244. doi: 10.1212/WNL.0000000000010244. Online ahead of print.
Authors: Nadav Amitay, Yair Zlotnik, Tara Coreanu, Lior Zeller, Ibrahim Abu-Salameh, Victor Novack, Gal Ifergane
Summary: The aim was to evaluate the association between post-concussive symptomatology and heading in professional soccer players, overcoming the bias of self-reported exposure, we evaluated several clinical neuropsychiatric symptoms using questionnaires after a thorough objective follow-up of players heading-exposure throughout an entire season We collected heading data for all Israeli Premier League players for an entire season using a web-based platform for performance analysis, which enabled us to quantify the exact number of headers per player. Players filled questionnaires regarding post-concussion symptoms, depression, anxiety and sleep disorders. We tested the association between the number of headers and each outcome using a negative binomial regression corrected for the hours played. 159 players were included, of which 79 considered in the high heading exposure group (49%) defined as more than median number of headings (1.34 per game hour). Among players without any past head injury, those with higher heading exposure were less likely to suffer post-concussion symptoms compared to players with low heading exposure (RR per heading per hour=0.94, 95%CI [0.912;0.963]). Players with high heading exposure suffered less from depression symptoms (RR=0.98, 95%CI [0.961;0.997]), anxiety (RR=0.98, 95%CI [0.958;0.997]) and sleep disorders (RR=0.98, 95%CI [0.961;0.996]). Professional soccer players with high heading rate do not display higher post-concussive symptomatology severity. Symptoms among players with low heading exposure might be explained by low resilience, possibly associated with an inferior heading technique. Alternatively, it can reflect heading avoidant behavior.
#12 Reliability of a musculoskeletal profiling test battery in elite academy soccer players
Reference: PLoS One. 2020 Jul 23;15(7):e0236341. doi: 10.1371/journal.pone.0236341. eCollection 2020.
Authors: Neval Grazette, Scot McAllister, Chin Wei Ong, Caroline Sunderland, Mary E Nevill, John G Morris
Download link: https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0236341&type=printable
Summary: The study aimed to quantify the measurement error / reliability of a musculoskeletal profiling test battery administered in young, elite academy soccer players, and to examine if the order in which the test battery was administered, and who it was administered by, influenced reliability. Players (n = 75; age 12-20 years; stature 1.47-1.95 m; body mass 36-89 kg) from U-12 to U-23 age groups were assigned to either: 1) intra-rater-fixed order; 2) intra-rater-non-fixed order; 3) inter-rater-fixed order; or, 4) inter-rater-non-fixed order groups. On two separate occasions separated by 3 to 7 days, 12 raters conducted a musculoskeletal profiling test battery comprising 10 tests (Supine Medial Hip Rotation, Supine Lateral Hip Rotation, Hamstring 90/90, Prone Medial Hip Rotation [degrees]; Combined Elevation, Thoracic Rotation, Weight-Bearing Dorsiflexion, Y-Balance [centimetres]; Beighton, Lumbar Quadrant [categorical]). The measurement error / reliability for tests measured in degrees and centimetres was evaluated using the intraclass correlation (relative reliability), coefficient of variation and ratio limits of agreement (absolute reliability). Intraclass correlations varied from 0.04 ("poor") to 0.95 ("excellent"), coefficient of variation from 2.9 to 43.4%, and the ratio limits of agreement from 1.058 (*/÷ 1.020) to 2.026 (*/÷ 1.319) for the tests measured in degrees and centimetres. The intraclass correlation, coefficient of variation and ratio limits of agreement were smallest for five out of eight tests measured in degrees and centimetres when the tests were administered in an intra-rater-fixed test order. These findings emphasise that different testing methods, and the administration of a musculoskeletal profiling test battery using a less than optimal design, will influence measurement error and hence test reliability. These observations need to be considered when investigating musculoskeletal function and age, injury, training or asymmetry in young, elite academy soccer players.
The aim was to assess the utility of an inertial sensor for assessing recovery in professional soccer players.
The aim was to examine the dose reponse effect of plyometric training on soccer performance variables.
Following studies were retrieved for this week:
#1 Nighttime Hypoglycemia in Children With Type 1 Diabetes After One Day of Football Tournament
Reference: Int J Sports Med. 2020 Jul 7. doi: 10.1055/a-1192-5992. Online ahead of print.
Authors: Mikołaj Kamiński, Andrzej Gawrecki, Aleksandra Araszkiewicz, Agnieszka Szadkowska, Bogda Skowrońska, Witold Stankiewicz, Arkadiusz Michalak, Aleksandra Cieluch, Katarzyna Dżygało, Sebastian Seget, Grzegorz Biegański, Anna Adamska, Katarzyna Ksiądz, Elektra Szymańska-Garbacz, Justyna Flotyńska, Dorota Zozulinska-Ziolkiewicz
Summary: The aim of the study was to investigate factors related to the occurrence of nighttime hypoglycemia after a football tournament in children with type 1 diabetes mellitus. The multicenter study (GoalDiab study) included 189 children and adolescents with type 1 diabetes mellitus, from 11 diabetes care centers in Poland. Hypoglycemia was defined according to the International Hypoglycemia Study Group Statement. We analyzed the data of 95 participants with completed protocols with regards to nighttime hypoglycemia (82% male), aged 11.6 (9.8-14.2) years, diabetes duration 5.0 (2.0-8.0) years. There were 47 episodes of nighttime Level 1 hypoglycemia (≤3.9 mmol/L). Occurrence of clinically important Level 2 hypoglycemia (<3.0 mmol/L) during a game period was positively associated with nighttime hypoglycemia (≤3.9 mmol/L) incident (Odds Ratio=10.7; 95% Confidence Interval: 1.1-100.2; p=0.04). Using Continuous Glucose Monitoring was negatively associated with the occurrence of nighttime hypoglycemia (≤3.9 mmol/L) compared with using glucose meters or Flash Glucose Monitoring (Odds Ratio=0.31; 95% Confidence Interval: 0.12-0.83; p=0.02). The occurrence of clinically important hypoglycemia related to physical activity is associated with the occurrence of hypoglycemia during the night. Continuous Glucose Monitoring is negatively associated with nighttime hypoglycemia after a day of competition.
#2 Feasibility and Safety of a Walking Football Program in Middle-Aged and Older Men With Type 2 Diabetes
Reference: Prog Cardiovasc Dis. 2020 Jul 4;S0033-0620(20)30137-7. doi: 10.1016/j.pcad.2020.06.014. Online ahead of print.
Authors: Ana Barbosa, João Brito, Júlio Costa, Pedro Figueiredo, André Seabra, Romeu Mendes
Summary: This study aimed to analyze the feasibility and safety of a community-based walking football program in middle-aged and older men with type 2 diabetes (T2D). Thirty-one male (age, 64.4 ± 4.5 years old; glycated hemoglobin, 6.7 ± 1.0%; body mass index: 28.8 ± 3.3 kg/m2) patients with T2D were recruited from primary health care units in Porto, Portugal. The participants engaged in a 12-wk walking football program (three sessions per week of 60 min; consisting of strength and conditioning exercises, technical skills drills, and small-sided walking football games). Exercise intensity was planned to be gradual throughout the program in three 4-wk phases (phase I, light-intensity; phase II, moderate-intensity; phase III, vigorous-intensity) through the manipulation of game constraints, and monitored by OMNI scale and heart rate reserve (HRR). Sessions' enjoyment level, and exercise-related injuries and adverse events were recorded in all sessions. The median (P25-P75) adherence to the program was 86.1% (77.8-97.2%). The median enjoyment levels reported by participants was 5 (4-5) points in phase I, 5 (5-5) points in phase II and 5 (5-5) points in phase III. Sessions' average subjective exercise intensity was 3.0 ± 0.6 points in OMNI scale in phase I, 3.5 ± 0.4 points in phase II, and 3.8 ± 0.4 points in phase III. Sessions' average HRR was 35.8 ± 6.7% in phase I, 41.6 ± 4.2% in phase II, and 37.3 ± 4.3% in phase III. Most participants attained vigorous-intensity peaks in all phases. Falls (n = 25) and musculoskeletal injuries (n = 8) were the most frequent adverse events. 31% of these events interfered with exercise participation, but no harm has resulted from it. A community-based walking football program for T2D patients revealed high levels of adherence and enjoyment, and light-to-vigorous exercise intensity. The adverse events were according to the expected for the population and activity. Therefore, walking football seems to be feasible and safe exercise strategy, and therefore has the potential for large scale implementation for T2D control.
#3 A Teaching Games for Understanding Program to Deal With Reasons for Dropout in Under-11 Football
Reference: Res Q Exerc Sport. 2020 Jul 7;1-12. doi: 10.1080/02701367.2020.1759767. Online ahead of print.
Authors: Carmen Barquero-Ruiz, María T Morales-Belando, José L Arias-Estero
Summary: Young players report that they dropout of organized football due to excessive emphasis on technical execution, low success, and the lack of autonomy and motivation experienced by players during training sessions. The purpose was to determine whether a TGfU intervention during a youth football program led players to improve in variables related to dropout. That means tactical-technical competence (decision-making, skill execution), success (successful game performance), autonomy (number of decisions made, player autonomy, number of game involvements, player participation), and motivation (enjoyment, intention to be physically active). Twenty under-11-players and two coaches were recruited from 17 clubs. A pretest-posttest design with a multi-method approach was used. Coaches were trained and mentored in TGfU. Data were collected using Game Performance Assessment Instrument, enjoyment and intention to be physically active scales, and two focus groups with the players and the coaches. Players improved in decision-making, skill execution, successful game performance, number of decisions made, number of game involvements, and intention to be physically active (p < .05). Participants attributed the results to the TGfU pedagogical features emphasized during the coaches' training and mentoring. Considering the reasons for dropout in football, in terms of excessive emphasis on technical execution, low success, and the lack of autonomy and motivation experienced by players, TGfU could be a useful pedagogical approach for teaching-learning organized youth football. The TGfU pedagogical features emphasized during coaches' training and mentoring could be crucial to obtain these results due to the fact that they were the sub-themes highlighted during the focus groups.
#4 Composite Indices of Femoral Neck Strength in Middle-Aged Inactive Subjects Vs Former Football Players
Reference: J Clin Densitom. 2020 Jun 12;S1094-6950(20)30093-7. doi: 10.1016/j.jocd.2020.06.002. Online ahead of print.
Authors: Boutros Finianos, Gautier Zunquin, El Hage Rawad
Summary: The purpose of this study was to compare composite indices of femoral neck strength ((compression strength index [CSI], bending strength index [BSI], and impact strength index [ISI]) in inactive middle-aged men (n = 20) and middle-aged former football players (n = 15). 35 middle-aged men participated in this study. Body composition and bone variables were evaluated by dual-energy X-ray absorptiometry. Composite indices of femoral neck strength (CSI, BSI, and ISI) were calculated. Handgrip strength, vertical jump, maximum power of the lower limbs (watts), horizontal jump, maximal half-squat strength, maximal bench-press strength, sprint performance (10 meters), and maximum oxygen consumption (VO2 max, ml/min/kg) were evaluated using validated tests. CSI, BSI, and ISI were significantly higher in football players compared to inactive men. Vertical jump, horizontal jump, maximal half-squat strength, VO2 max and sprint performance were significantly different between the 2 groups. CSI, BSI, and ISI remained significantly higher in football players compared to inactive men after adjusting for physical activity level. The current study suggests that former football practice is associated with higher composite indices of femoral neck strength in middle-aged men.
#5 Association Between the Acute to Chronic Workload Ratio and Injury Occurrence in Young Male Team Soccer Players: A Preliminary Study
Reference: Front Physiol. 2020 Jun 24;11:608. doi: 10.3389/fphys.2020.00608. eCollection 2020.
Authors: Hamid Arazi, Abbas Asadi, Farhood Khalkhali, Daniel Boullosa, Anthony C Hackney, Urs Granacher, Hassane Zouhal
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7327085/pdf/fphys-11-00608.pdf
Summary: This study aimed to investigate the relationship between the acute to chronic workload ratio (ACWR), based upon participant session rating of perceived exertion (sRPE), using two models [(1) rolling averages (ACWRRA); and (2) exponentially weighted moving averages (ACWREWMA)] and the injury rate in young male team soccer players aged 17.1 ± 0.7 years during a competitive mesocycle. Twenty-two players were enrolled in this study and performed four training sessions per week with 2 days of recovery and 1 match day per week. During each training session and each weekly match, training time and sRPE were recorded. In addition, training impulse (TRIMP), monotony, and strain were subsequently calculated. The rate of injury was recorded for each soccer player over a period of 4 weeks (i.e., 28 days) using a daily questionnaire. The results showed that over the course of the study, the number of non-contact injuries was significantly higher than that for contact injuries (2.5 vs. 0.5, p = 0.01). There were also significant positive correlations between sRPE and training time (r = 0.411, p = 0.039), ACWRRA (r = 0.47, p = 0.049), and ACWREWMA (r = 0.51, p = 0.038). In addition, small-to-medium correlations were detected between ACWR and non-contact injury occurrence (ACWRRA, r = 0.31, p = 0.05; ACWREWMA, r = 0.53, p = 0.03). Explained variance (r 2) for non-contact injury was significantly greater using the ACWREWMA model (ranging between 21 and 52%) compared with ACWRRA (ranging between 17 and 39%). In conclusion, the results of this study showed that the ACWREWMA model is more sensitive than ACWRRA to identify non-contact injury occurrence in male team soccer players during a short period in the competitive season.
#6 Comment on: "Changes in Skeletal Muscle Glycogen Content in Professional Soccer Players before and after a Match by a NonInvasive MuscleSound ® Technology. A Cross Sectional Pilot Study
Reference: Nutrients 2020, 12(4), 971"
Authors: Niels Ørtenblad, Joachim Nielsen, Kasper D Gejl, Harry E Routledge, James P Morton, Graeme L Close, David C Niemann, Julia L Bone, Louise M Burke
Download link: https://www.mdpi.com/2072-6643/12/7/2070/pdf
#7 Reply to Comment on: "Changes in Skeletal Muscle Glycogen Content in Professional Soccer Players before and after a Match by a Non-Invasive MuscleSound ® Technology. A Cross Sectional Pilot Study
Reference: Nutrients. 2020 Jul 12;12(7):E2066. doi: 10.3390/nu12072066.
Authors: Iñigo San-Millán, John C Hill, Julio Calleja-González
Download link: https://www.mdpi.com/2072-6643/12/7/2066/pdf
#8 Sodium Bicarbonate Supplementation Does Not Improve Running Anaerobic Sprint Test Performance in Semiprofessional Adolescent Soccer Players
Reference: Int J Sport Nutr Exerc Metab. 2020 Jul 15;1-8. doi: 10.1123/ijsnem.2020-0031. Online ahead of print.
Authors: Rodrigo Dos Santos Guimarães, Alcides Correa de Morais Junior, Raquel Machado Schincaglia, Bryan Saunders, Gustavo Duarte Pimentel, João Felipe Mota
Summary: Ergogenic strategies have been studied to alleviate muscle fatigue and improve sports performance. Sodium bicarbonate (NaHCO3) has improved repeated sprint performance in adult team-sports players, but the effect for adolescents is unknown. The aim of the present study was to evaluate the effect of NaHCO3 supplementation on repeated sprint performance in semiprofessional adolescent soccer players. In a double-blind, placebo-controlled, crossover trial, 15 male semiprofessional adolescent soccer players (15 ± 1 years; body fat 10.7 ± 1.3%) ingested NaHCO3 or a placebo (sodium chloride) 90 min before performing the running anaerobic sprint test (RAST). A countermovement jump was performed before and after the RAST, and ratings of perceived exertion, blood parameters (potential hydrogen and bicarbonate concentration), and fatigue index were also evaluated. Supplementation with NaHCO3 promoted alkalosis, as demonstrated by the increase from the baseline to preexercise, compared with the placebo (potential hydrogen: +0.07 ± 0.01 vs. -0.00 ± 0.01, p < .001 and bicarbonate: +3.44 ± 0.38 vs. -1.45 ± 0.31 mmol/L, p < .001); however, this change did not translate into an improvement in RAST total time (32.12 ± 0.30 vs. 33.31 ± 0.41 s, p = .553); fatigue index (5.44 ± 0.64 vs. 6.28 ± 0.64 W/s, p = .263); ratings of perceived exertion (7.60 ± 0.33 vs. 7.80 ± 0.10 units, p = .525); countermovement jump pre-RAST (32.21 ± 3.35 vs. 32.05 ± 3.51 cm, p = .383); or countermovement jump post-RAST (31.70 ± 0.78 vs. 32.74 ± 1.11 cm, p = .696). Acute NaHCO3 supplementation did not reduce muscle fatigue or improve RAST performance in semiprofessional adolescent soccer players. More work assessing supplementation in this age group is required to increase understanding in the area.
#9 Effects of 6 Weeks Direct Instruction and Teaching Games for Understanding Programs on Physical Activity and Tactical Behaviour in U-12 Soccer Players
Reference: Int J Environ Res Public Health. 2020 Jul 12;17(14):E5008. doi: 10.3390/ijerph17145008.
Authors: Juan Vicente Sierra-Ríos, Filipe Manuel Clemente, Ezequiel Rey, Sixto González-Víllora
Download link: https://www.mdpi.com/1660-4601/17/14/5008/pdf
Summary: The purpose of this study was to compare the effects of 6 weeks direct instruction and teaching games for understanding (TGfU) programs on the decision-making and execution (post-interventions), as well, as on the physical activity (PA) levels during sessions. Thirty under-12 football players participated in this study (age: 10.3 ± 0.45 years) and were randomly assigned to TGfU (n = 15) or direct instruction (n = 15) group. Two sessions/week were implemented. Results revealed that TGfU promoted higher levels (p = 0.043; d = 2.99) of light PA (28.96%) compared with direct instruction (27.55%). Non-significant higher sedentary PA levels (p = 0.073; d = 2.62) were found in the control group (35.48%). In terms of tactical principles, conservation of the ball increased the percentage of moderate to vigorous physical activity in TGfU (43.60%) compared with direct instruction (38.05%). According to the Game Performance Evaluation Tool (GPET), significant improvements (p = 0.018, d = 3.78) of the attacking player with the ball in the percentage of change between groups in the unsuccessful execution in TGfU (% = -62.2) were observed compared with direct instruction (% = 14.2). TGfU seems to be more appropriate than direct instruction to increase the light PA levels during sessions while no significant differences were found between programs in moderate and vigorous intensities. Regarding the effects of programs in decisions, greater improvements in decisions with the ball were found in TGFU compared to DI.
#10 Adductor Muscles Strength and Strength Asymmetry as Risk Factors for Groin Injuries among Professional Soccer Players: A Prospective Study
Reference: Int J Environ Res Public Health. 2020 Jul 9;17(14):E4946. doi: 10.3390/ijerph17144946.
Authors: Goran Markovic, Nejc Šarabon, Jelena Pausic , Vedran Hadžić
Download link: https://www.mdpi.com/1660-4601/17/14/4946/pdf
Summary: The aim of this study was to prospectively examine the association between isometric hip adductor strength and between-limb strength asymmetry to groin injuries in male professional soccer players. Isometric hip adductor strength and between-limb strength asymmetry of 45 professional outfield soccer players from three First Division teams were tested during the 2017/2018 preseason. Players were then monitored throughout the 2017/2018 season for groin injuries. Ten groin injuries were recorded. When compared with uninjured players, players who sustained groin injury had significantly lower strength of respective muscle groups and significantly higher between-limb strength asymmetries (all p < 0.05; ES = 1.16 and 0.88; mean % difference = 26% and 51%). Isometric hip adductor strength had a significant inverse relationship with the incidence of occurring groin injuries (p = 0.016). No significant relationship between hip adductor strength asymmetry and the incidence of future groin injury was observed (p = 0.09). Finally, players' age and previous groin injury were not significantly associated with the incidence of future groin injuries (all p > 0.05). These results generally suggest that isometric adductor strength is a significant predictor of future groin injuries in men's professional football; however, due to the relatively low sample size, further studies are required.
#11 Injuries on the Youth Soccer (Football) Field: Do Additional Referees Reduce Risk? Randomized Crossover Trial
Reference: J Pediatr Psychol. 2020 Jul 11;jsaa050. doi: 10.1093/jpepsy/jsaa050. Online ahead of print.
Authors: David C Schwebel, D Leann Long, Leslie A McClure
Summary: Youth soccer injury can be prevented through various means, but few studies consider the role of referees. Following previous research suggesting children take fewer risks when supervised intensely, this randomized crossover trial evaluated whether risky play and injuries decrease under supervision from three referees instead of one referee. Youth soccer clubs serving a metropolitan U.S. area participated. Boys' and girls' clubs at under age 10 (U10) and under age 11 (U11) levels were randomly assigned such that when the same clubs played each other twice in the same season, they played once with one referee and once with three referees. A total of 98 games were videotaped and subsequently coded to obtain four outcomes: collisions between players, aggressive fouls (involving physical player-to-player contact) called by the referee(s) on the field, aggressive fouls judged by trained coders, and injuries requiring adult attention or play stoppage. Poisson mixed model results suggest players in the 98 games committed fewer aggressive fouls, as identified independently by referees (rate ratio [RR] 0.58; 95% confidence interval [CI] 0.35-0.96) and by researchers (RR 0.67; 95% CI 0.50-0.90), when there were three referees versus one referee. Collisions (RR 0.98; 95% CI 0.86-1.12) and injury rates (RR 1.15; 95% CI 0.60-2.19) were similar across conditions. When the same youth soccer clubs played with three referees rather than one, they committed fewer aggressive fouls. More intense supervision created better rule adherence. Injury rates were unchanged with increased supervision. Results raise questions concerning whether financial investment in additional referees on youth soccer fields yields safety benefits.
#12 'When you have the adrenalin pumping, it kind of flushes out any negative emotions': a qualitative exploration of the benefits of playing football for people with mental health difficulties
Reference: J Ment Health. 2020 Jul 17;1-8. doi: 10.1080/09638237.2020.1793119. Online ahead of print.
Authors: Mark Llewellyn, Alecia L Cousins, Philip John Tyson
Summary: Physical activity is a factor by which mental health can be improved. However, the association between mental health and physical exercise, in a "team-based sport" setting within the community, remains unclear. The current paper aims to provide an evaluation of a football programme, implemented by Time to Change Wales, funded by the Welsh Government, to improve mental health. Participants attended weekly 90-120 minute football sessions, held in local community venues across Wales, UK, with no requirement on the number of sessions that participants had to attend. A qualitative method was employed to explore the experiences of those who took part. Individuals who participated in the programme reported psychosocial and physical benefits, such as improved physical and mental health, improved social confidence and having a sense of purpose added to their day-to-day living. Factors affecting participation were also identified within the data, such as environmental barriers. The findings provide both support and contextual extension to previous research in this area; demonstrating the positive effects of sport-based therapy for those with mental health difficulties. Implications and conclusions should be used to inform future research into developing community sport-based programmes to improve mental health.
The study aimed to identify associations between running performance and game performance indicators in professional footballers compared to their playing position.
The purpose was to assess the relation between training workload and SSGs' density.
Following studies were retrieved for this week:
#1 Short and Long-Term Effects of a Simple-Strength-Training Program on Injuries Among Elite U-19 Soccer Players
Reference: Res Q Exerc Sport. 2020 Jul 7;1-9. doi: 10.1080/02701367.2020.1741498. Online ahead of print.
Authors: Javier Raya-González, Luis Suarez-Arrones, Javier Sanchez-Sanchez, Rodrigo Ramirez-Campillo, Fabio Y Nakamura, Eduardo Sáez De Villarreal
Summary: The aim of this study was to examine the short and long-term effects of a simple strength training program on muscle injury prevention in soccer players. Twenty-seven U-19 elite male soccer players participated in the study. The investigation was conducted over two consecutive and similar seasons (e.g., the same staff, players, weekly training schedule), the first being the control and the second the experimental season. The strength program was carried out 2 times per week, for 10 weeks, during part of the preseason and in-season. Injury incidence and absence days were compared between both seasons, according to the injury rate ratio (IRR), with 95% CI and the Z test. A lower number of total and hamstring injuries were recorded during the experimental (9 and 2, respectively) compared to the control (15 and 7, respectively) period. During the 10 weeks intervention period, the injury rate ratio (IRR) was lower in the experimental season than in the control season (IRR = 8.12; 95% CI: 1.00-66.03; effect size (ES) = 3.30, large). In addition, there was a decline in absence days per injury and in the number of absence days/1000 h (IRR = 2.44; 95% CI: 1.90-3.14; ES = 1.12) during the experimental season. The results of this study suggest that this simple strength-training program could reduce the muscle injury incidence during its application period in young soccer players.
#2 Role of Sports Psychology and Sports Nutrition in Return to Play From Musculoskeletal Injuries in Professional Soccer: An Interdisciplinary Approach
Reference: Eur J Sport Sci. 2020 Jul 7;1-19. doi: 10.1080/17461391.2020.1792558. Online ahead of print.
Authors: Ian Rollo, James M Carter, Graeme L Close, Javier Yanguas Leyes, Antonio Gomez, Daniel Medina Leal, Joan L Duda, Donough Holohan, Sam J Erith, Leslie Podlog
Summary: Musculoskeletal injuries are prevalent in professional soccer and can result in lost training time or match play. It is intuitive that the "return to play" (RTP) pathway will depend, in large part, on the expertise of sports medicine practitioners (e.g., surgeons, physicians, physiotherapists) responsible for player's recovery. Consensus statements on returning athletes to sport following injury acknowledge the contributions of sport psychology and sports nutrition. However, specific consideration on how to integrate these two recognized - but often overlooked components of injury rehabilitation - into existing sport medicine approaches has yet to be examined. Using a framework of milestones directed by the medical physician and physical trainer, evidence is summarised and suggestions provided on the integration of sports psychology and sports nutrition into an interdisciplinary RTP approach. We examine recovery from a phase approach (acute injury and functional recovery) to highlight interdisciplinary opportunities in the management of musculoskeletal soccer injuries. An interdisciplinary approach is understood to achieve outcomes that could not be achieved within the framework of a single discipline. The incorporation of sports psychology and nutrition theoretically compliment milestones used in current medically-based RTP models. Our hope is that this article serves as a catalyst for interdisciplinary practice and research - not only in sports nutrition and sports psychology - but across all sport and exercise disciplines.
#3 Assessment of Energy Availability and Associated Risk Factors in Professional Female Soccer Players
Reference: Eur J Sport Sci. 2020 Jul 7;1-27. doi: 10.1080/17461391.2020.1788647. Online ahead of print.
Authors: Samantha L Moss, Rebecca K Randell, Darren Burgess, Stephanie Ridley, Caibre ÓCairealláin, Richard Allison, Ian Rollo
Summary: This study aimed to assess energy availability (EA), alongside possible risk factors of reduced or low EA of professional female soccer players during a competitive season. Thirteen players (age: 23.7 ± 3.4 y, stature: 1.69 ± 0.08 m, body mass: 63.7 ± 7.0 kg) engaged in a 5-day (two rest days, one light training, heavy training and match day) monitoring period. Energy intake (EI) and expenditure during exercise (EEE) were measured. EA was calculated and categorised as optimal, reduced or low (≥45, 31-44, ≤30 kcal·kg FFM-1·day-1, respectively). Relationships between EA and bone mineral density, resting metabolic rate (RMR), plasma micronutrient status, biochemical markers and survey data were assessed. EA was optimal for 15%, reduced for 62% and low for 23% of players. Higher EA was observed on rest days compared to others (P<0.05). EA was higher for the light compared to the heavy training day (P<0.001). EEE differed significantly between days (P<0.05). EI (2124 ± 444 kcal), carbohydrate (3.31 ± 0.64 g·kg·day-1) and protein (1.83 ± 0.41 g·kg·day-1) intake remained similar (P>0.05). Survey data revealed 23% scored ≥ 8 on the Low Energy Availability in Females Questionnaire and met criteria for low RMR (ratio <0.90). Relationships between EA and risk factors were inconclusive. Most players displayed reduced EA and did not alter EI or carbohydrate intake to training or match demands. Although cases of low EA were identified, further work is needed to investigate possible long-term effects and risk factors of low and reduced EA separately to inform player recommendations.
#4 The Influence of a Soccer Season on Non-Contact Injury and Isokinetic Peak Torque of the Quadriceps and Hamstrings in Professional Youth Soccer Players
Reference: Res Sports Med. 2020 Jul 6;1-14. doi: 10.1080/15438627.2020.1771336. Online ahead of print.
Authors: Colin Charles Brow, Andisheh Bakhshi, Russ Wrigely, Viswanath B Unnithan
Summary: Isokinetic strength screening is utilized in professional soccer. However, there has been little research on the interaction between seasonal changes in players' peak torque (PT) and injury incidence. Twenty-five (age 16.5[Formula: see text]0.68 years) professional youth soccer players participated in the study. Bilateral isokinetic concentric (CON) and eccentric (ECC) testing of Quadriceps (Q) and Hamstrings (H) were conducted at three time-points across the season. Absolute CON and ECC PT were measured at 60 degree/sec and in a supine 170-degree position. Testing data was normalized to body mass. A mixed design (2 by 3) repeated measures ANOVA with injury as a co-variate was conducted to evaluate the effect of season and/or limb dominance on PT and injury incidence. With regard to the seasonal variation and injury incidence, an interaction was identified with respect to non-dominant limb (NDL) QCON (p = 0.01) and to a lesser extent the dominant limb (DL) QCON (p = 0.05). The seasonal variation of the PT of the NDL QCON was different between the injured and non-injured individuals. Non-injured individuals, QCON strength increased over the course of the season. While for the Injured players, QCON declined from pre-season to mid-season then increased but never recovered to starting pre-season values.
#5 Muscular Strength Imbalances Are Not Associated With Skin Temperature Asymmetries in Soccer Players
Reference: Life (Basel). 2020 Jul 2;10(7):E102. doi: 10.3390/life10070102.
Authors: Rodrigo Mendonça Teixeira, Rodolfo A Dellagrana, Jose I Priego-Quesada, João Claudio B P Machado, Juliano Fernandes da Silva, Tallyne Mayara Pacheco Dos Reis, Mateus Rossato
Download link: https://www.mdpi.com/2075-1729/10/7/102/pdf
Summary: Although strength imbalances using isokinetic dynamometer have been examined for injury risk screening in soccer players, it is very expensive and time-consuming, making the evaluation of new methods appealing. The aim of the study was to analyze the agreement between muscular strength imbalances and skin temperature bilateral asymmetries as well as skin temperature differences in the hamstrings and quadriceps. The skin temperature of the anterior and posterior thigh of 59 healthy male soccer athletes was assessed at baseline using infrared thermography for the identification of hamstrings-quadriceps skin temperature differences and thermal asymmetries (>0.5 °C). Subsequently, concentric and eccentric peak torque of the quadriceps and hamstrings were considered in the determination of the ratios, as well as muscular asymmetries (>15%). When considering the torque parameters, 37.3% (n = 22) of the players would be classified as high risk for injuries. The percentage of those presenting skin temperature imbalances superior to 0.5 °C was 52.5% (n = 31). The skin temperature assessment showed sensitivity (22%) and specificity (32.2%) to identify torque asymmetries, demonstrating the inability to identify false negatives (15.3%) and false positives (30.5%) from all soccer athletes. In conclusion, skin temperature differences between hamstrings and quadriceps could be more related to thermoregulatory factors than strength imbalances.
#6 Effects of a 20-min Nap After Sleep Deprivation on Brain Activity and Soccer Performance
Reference: Int J Sports Med. 2020 Jul 6. doi: 10.1055/a-1192-6187. Online ahead of print.
Authors: Amornpan Ajjimaporn, Papatsorn Ramyarangsi, Vorasith Siripornpanich
Summary: We examined effects of a 20-min nap following 3 h of sleep deprivation on brain wave activity, auditory reaction time, the running-based anaerobic sprint test, leg muscle strength and the rating of perceived exertion in male college soccer players. Eleven players underwent three sleep conditions; normal sleep, sleep deprivation and 20-min nap after sleep deprivation. The sleep deprivation demonstrated an increase in the mean power of delta waves over the frontal area and a decrease in the mean power of alpha waves over the parietal area compared to the normal sleep. The nap and the sleep deprivation showed an increase in auditory reaction time compared with those in the normal sleep. The sleep deprivation demonstrated a decrease in the running-based anaerobic sprint test compared to the normal sleep, whereas the nap has partially reversed only minimal power and average power of the running-based anaerobic sprint test. The nap showed a recovery effect on leg muscle strength, but not on the rating of perceived exertion compared with the sleep deprivation. Thus, a 20-min nap after sleep deprivation did not completely return brain activity back to active state and did not entirely reverse the negative impact of sleep deprivation on soccer performance in soccer players.
#7 Physical Match Performance in Sub-elite Soccer Players - Introduction of a New Index
Reference: Int J Sports Med. 2020 Jul 6. doi: 10.1055/a-1165-1950. Online ahead of print.
Authors: Lars Reinhardt, Stephan Schulze, Rene Schwesig, Eduard Kurz
Summary: This investigation examined the position-specific physical performance in different locomotor categories and physiological demands concurrently in official games of sub-elite players and to present a new performance index (PI). Time-motion (distance, velocity, acceleration) and heart rate data of 55 soccer players were simultaneously captured via a GPS tracking system. The relationship between external and internal match-load (PI) was determined on the basis of heart rate, average velocity and acceleration. In contrast to the mean heart rate (85.2±3.2%, P=0.806, ηp²=0.03), the average total distance covered (9946±715 m) was largely affected by players' position (P<0.001, ηp²=0.63). Furthermore, a mixed design ANOVA showed a large interaction effect between position and locomotor category (P<0.001, ηp²=0.44). On average, PI was 1.57±0.37 m/min²/%, with notably lower values in the 2nd half. The position-specific profiles already reported for higher leagues were also present in sub-elite soccer players. Despite lower values for total distance and smaller distances in the high-intensity zones (>14.4 km/h), internal loads were comparable to those observed in European top leagues. In comparison to a performance measure that ignores accelerations, PI was shown to be less dependent on the playing position and had higher variability. Consequently, PI is better suited to distinguish between players' performance
#8 The Developmental and Professional Activities of Female International Soccer Players From Five High-Performing Nations
Reference: J Sports Sci. 2020 Jul 4;1-9. doi: 10.1080/02640414.2020.1789384. Online ahead of print.
Authors: Paul R Ford, Nicola J Hodges, David Broadbent, Donna O'Connor , Dawn Scott, Naomi Datson, Helena A Andersson, A Mark Williams
Summary: We study the developmental and professional activities engaged in by 86 female adult soccer players from the senior national teams of Australia, Canada, England, Sweden, and the United States of America. Players completed the Participation History Questionnaire (PHQ) to elicit the amount and type of activities engaged in across their developmental and professional years, including milestones, soccer-specific activity and engagement in other sport activity. Greater specialisation than diversification characterised their childhood developmental activities, including all players starting in soccer in childhood and accumulating more hours in soccer activity than other sports during this period. However, interindividual variation further characterised these childhood activities, with a proportion of players diversifying into other sports and/or soccer play to a greater or lesser degree during childhood when compared to the other players. The amount of coach-led soccer practice increased for all players across their development culminating in an average of 15-16 h/wk across a 40-week season in early adulthood. In contrast, the amount of engagement in other sports and soccer peer-led play varied between players but generally decreased across adolescence to negligible amounts in late adolescence. Findings are commensurate with the deliberate practice framework and early engagement.
#9 Effects of Acute Inspiratory Loading During Treadmill Running on Cerebral, Locomotor and Respiratory Muscle Oxygenation in Women Soccer Players
Reference: Respir Physiol Neurobiol. 2020 Jul 2;103488. doi: 10.1016/j.resp.2020.103488. Online ahead of print.
Authors: Flavia Rossi Caruso, Bruno Archiza, Daniela Kuguimoto Andaku, Renata Trimer, José Carlos Bonjorno-Junior, Claudio Ricardo de Oliveira, Cleiton A Libardi, Shane A Phillips, Ross Arena, Renata Gonçalves Mendes, Audrey Borghi-Silva
Summary: Respiratory limitation can be a primary mechanism for exercise cessation in female athletes. This study aimed to assess the effects of IL on intercostal (IM), vastus lateralis (VL) and cerebral (Cox) oxygenation in women soccer players during high-intensity dynamic exercise. Ten female soccer players were randomized to perform in order two constant-load tests on a treadmill until the exhaustion time (Tlim) (100% of maximal oxygen uptake- V̇O2). They breathed freely or against a fixed inspiratory loading (IL) of 41 cm H2O (∼30% of maximal inspiratory pressure). Oxygenated (Δ[OxyHb]), deoxygenated (Δ[DeoxyHb]), total hemoglobin (Δ[tHb]) and tissue saturation index (ΔTSI) were obtained by NIRs. Also, blood lactate [La-] was obtained. IL significantly reduced Tlim (224 ± 54 vs 78 ± 20 sec; P < 0.05) and increased [La-], V̇O2, respiratory cycles and dyspnea when corrected to Tlim (P < 0.05). IL also resulted in decrease of Δ[OxyHb] of Cox and IM during exercise compared with rest condition. In addition, decrease of Δ[OxyHb] was observed on IM during exercise when contrasted with Sham (P < 0.05). Furthermore, significant higher Δ[DeoxyHb] of IM and significant lower Δ[DeoxyHb] of Cox were observed when IL was applied during exercise in contrast with Sham (P < 0.05). These results were accompanied with significant reduction of Δ[tHb] and ΔTSI of IM and VL when IL was applied (P < 0.05). High-intensity exercise with IL decreased respiratory and peripheral muscle oxygenation with negative impact on exercise performance. However, the increase in ventilatory work did not impact cerebral oxygenation in soccer players.
#10 Body Composition of National Collegiate Athletic Association (NCAA) Division I Female Soccer Athletes Through Competitive Seasons
Reference: Int J Sports Med. 2020 Jul 10. doi: 10.1055/a-1177-0716. Online ahead of print.
Authors: Erica Roelofs, April Bockin, Tyler Bosch, Jonathan Oliver, Christopher W Bach, Aaron Carbuhn, Philip R Stanforth, Donald R Dengel
Summary: The purpose of this study was to examine body composition of National Collegiate Athletic Association Division I female soccer players by position and season. One hundred seventy-five female athletes were categorized by positions of forward (n=47), midfielder (n=51), defender (n=57), and goalkeeper (n=20). A dual X-ray absorptiometry scan assessed percent body fat, total lean mass, total fat mass, arm and leg lean mass and fat mass, and visceral adipose tissue. Goalkeepers had significantly higher total, arm, and leg lean mass and fat mass compared to all other positions (p<0.05). For seasonal changes, body fat percentage was significantly higher in winter off-season (26.7%) compared to summer off-season (25.7%) and pre-season (25.8%; p<0.01) for all positions. Total and leg lean mass was significantly lower in winter off-season compared to all other seasons, and total lean mass was significantly higher in summer off-season than pre-season (p<0.01). Overall, goalkeepers were significantly different than all other positions. Body fat percentage increased and lean mass decreased in winter off-season indicating potential undesired changes in training and/or nutrition over the break whereas lean mass was the highest in summer off-season potentially reflecting the emphasis on resistance training and increased volume of training.
#11 Developing a Two-Dimensional Landscape Model of Opportunities for Penetrative Passing in Association Football - Stage I
Reference: J Sports Sci. 2020 Jul 10;1-8. doi: 10.1080/02640414.2020.1786991. Online ahead of print.
Authors: Pedro Passos, Rodrigo Amaro E Silva, Luís Gomez-Jordana, Keith Davids
Summary: This study investigated a method for modelling a landscape of opportunities for penetrative passing completed on the ground by ball carriers in association football. Analysis of video footage of competitive, professional football performance was undertaken, identifying a sample (n = 20) of attacking sub-phases of gameplay which ended in a penetrative pass being made between defenders to a receiver. Players' relative co-positioning during performance was modelled using bi-dimensional x and y coordinates of each player recorded at 25 fps. Data on player movements during competitive interactions were captured using an automatic video tracking system, recording player co-locations emerging over time, as well as current and estimated running velocities. Results revealed that the half spaces between the midfield and both sidelines were the key locations on field providing most affordances for penetrating passes in the competitive performance sample analysed. Due to the dynamics of players' co-adaptive performance behaviours, it was expected that opportunities for penetrative passing by ball carriers would not display a homogeneous space-time spread across the entire field. Results agreed with these expectations, showing how a landscape of opportunities for penetrative passing might be specified by information emerging from continuous player interactions in competitive performance.
#12 Influence of Training Schedules on Objective Measures of Sleep in Adolescent Academy Football Players
Reference: J Strength Cond Res. 2020 Jul 7. doi: 10.1519/JSC.0000000000003724. Online ahead of print.
Authors: Georgia A Brown, Stella Veith, John A Sampson, Matthew Whalan, Hugh H K Fullagar
Summary: Football academy settings may pose risks to adolescent athletes achieving sufficient sleep because of the contextual challenges these players face (e.g., psychosocial pressure, changes in training, competition, and academic stress). Given the importance of sleep to overall health as well as physical athletic development and injury risk, this study aimed to investigate whether differences in training schedules (morning vs. evening training sessions) affected objective measures of sleep in adolescent academy football (soccer) players. Twelve academy players (mean age 14.18 ± 1.36 years) wore an ActiGraph accelerometer on nights before, and nights of, training days in 2 separate weeks where morning (09:00-11:00 hours) and evening (18:00-20:00 hours) training occurred. Objective sleep parameters and training load data were collected. Night-time sleep periods were categorized as sleep preceding morning training, preceding evening training, or after evening training. One-way univariate and multivariate analyses of variance for repeated measures were performed to determine the impact of the training schedule on sleep. Significance levels were set at p < 0.05. The total sleep time was below the recommended guidelines (<8 hours) across conditions. A large significant effect of the training schedule on time attempted to fall asleep (p = 0.004, effect size [ES] = 0.40) and time of sleep (p = 0.003, ES = 0.41) was present, with post-evening sessions resulting in the latest times. Overall, the players' sleep behavior was resilient to changes in training schedules. However, the low sleep durations (and potential risks to physical performance/injury) suggest that sleep education coupled with practical interventions are required in this cohort.
The aim was to provide in-season training load for different days within a mesocycle in elite soccer players.
The aim was to analyze the effects of 2 resistance programs using the same relative load but different repetition volume.
Following studies were retrieved for this week:
#1 Evaluation of Ball Passing and Space Detection Skill in Soccer: Implementation of Two New Soccer Tests
Reference: Res Sports Med. 2020 Jul 1;1-11. doi: 10.1080/15438627.2020.1789133. Online ahead of print.
Authors: Evangelos Bekris, Stylianos Kounalakis, Ioannis Ispirlidis, Athanasios Katis
Summary: The present study examined the validity and reliability of two new soccer tests: the Passing Accuracy Test (PAT), which assesses ball passing accuracy in combination with visual stimulus recognition and the Passing and Visual Recognition test (PVR), which assesses player's space detection skill in a 360 degrees range along with the frequency and the accuracy of ball passing technique. Participants were allocated in four (4) groups based on their age: the Under 11 (U11) group consisted of 101 players, the Under 14 (U14) group consisted of 100 players, the Under 17 (U17) group consisted of 118 players and the Adults (AD) group consisted of 43 players. The typical error, the limits of agreement and the ICC of PAT and PVR test were examined. The results of the study showed high validity and reliability for both tests with the exception in PAT for adult group (ICC = 0.33-0.83; P < 0.05). Therefore, both tests could be valuable tools to assess the accuracy of ball passing technique and the space detection skill in players of different ages.
#2 Talipes Equinus Deformity Caused by Fibrous Gastrocnemius Muscle Contracture After Direct Contusion in Football Players: Report of Two Cases
Reference: J Foot Ankle Surg. Jul-Aug 2020;59(4):816-820. doi: 10.1053/j.jfas.2019.10.004.
Authors: Yoichi Kaneuchi, Ken-Ichi Otoshi, Michiyuki Hakozaki, Kazuo Watanabe, Shin-Ichi Konno
Summary: Two main causes of gastrocnemius contracture have been considered: 1) congenital deformities in pediatric patients, such as limb-length discrepancy, cerebral palsy, flatfoot, and clubfoot; and 2) secondary conditions such as immobilization for trauma or a nonfunctional limb. Talipes equinus deformity caused by fibrous gastrocnemius contracture after a direct muscle contusion is extremely rare. We describe 2 cases of talipes equinus deformity caused by fibrous gastrocnemius muscle contracture after a direct contusion in football players. Both of the players had a talipes equinus deformity with a severe restriction of ankle dorsiflexion, and a cord-like structure was observed at the proximal part of the lateral gastrocnemius head. Both patients' histological examinations revealed fibrous tendon-like tissue within the structure. After discission of the cord-like structures, the restriction of ankle dorsiflexion was completely resolved, and the patients were able to fully return to playing football without any discomfort in their calves.
#3 Training Soccer Skills to Adolescents With Autism Spectrum Disorder via Peer-Mediated Behavioral Skills Training
Reference: Behav Anal Pract. 2019 Aug 19;13(2):454-461. doi: 10.1007/s40617-019-00381-2.
Authors: Caitlyn Chambers, Keith C Radley
Summary: Peer-mediated interventions have been identified as efficient means of promoting the acquisition of skills of students with autism spectrum disorder (ASD). Limited research, however, has evaluated the utility of such procedures for promoting recreational skills that may allow for greater interaction with peers. The purpose of the current study was to evaluate the effectiveness of peer-mediated behavioral skills training on the acquisition of discrete soccer skills of 3 students with ASD. Following the implementation of the intervention, all participants demonstrated substantial improvements in the accuracy of the target soccer skills.
#4 Relationships Between Controlling Interpersonal Coaching Style, Basic Psychological Need Thwarting, and Burnout, in Adolescent Soccer Players
Reference: Int J Environ Res Public Health. 2020 Jul 7;17(13):E4909. doi: 10.3390/ijerph17134909.
Authors: Verónica Morales-Sánchez, Miriam Crespillo-Jurado, David Jiménez-López, Juan P Morillo-Baro, Antonio Hernández-Mendo, Rafael E Reigal
Download link: https://www.mdpi.com/1660-4601/17/13/4909/pdf
Summary: The aim of this paper is to analyze the relationships between a controlling interpersonal style, psychological need thwarting and burnout in adolescent soccer players and to test a structural equation model to analyze whether (a) a controlling interpersonal style is a predictor of psychological need thwarting and whether (b) psychological need thwarting is a predictor of burnout. A total of 103 male soccer players between the ages of 12 and 17 participated in the research (M = 14.91; SD = 5.56). The Controlling Coach Behaviors Scale, the Psychological Need Thwarting Scale, and the Athlete Burnout Questionnaire were used to evaluate the variables under study. The analyses revealed significant relationships between a controlling interpersonal style, psychological need thwarting and burnout. Furthermore, the proposed structural equations model, using the partial least squares (PLS) method, showed that a controlling style is a positive predictor of basic psychological need thwarting and that the latter is a predictor of burnout, as well as revealing an indirect relationship between a controlling style and burnout. This indirect effect of the controlling style variable on burnout can be enhanced (or attenuated) by the basic psychological need thwarting variable, which acts as a modulator.
#5 The Effects of Physical Fitness on Postactivation Potentiation in Professional Soccer Athletes
Reference: J Strength Cond Res. 2020 Jul 7. doi: 10.1519/JSC.0000000000003711. Online ahead of print.
Authors: Mauro A Guerra Jr, Leonardo C Caldas, Helder L Souza, Jason Tallis, Michael J Duncan, Lucas Guimarães-Ferreira
Reference: The effects of physical fitness on postactivation potentiation in professional soccer athletes.
Summary: The purpose was to investigate the relationship of the response to postactivation potentiation (PAP) with scores of physical fitness. Twenty-four professional male soccer players undertook tests of agility, muscular power, aerobic capacity, and body composition. Conditioning activities (CAs) were performed consisting of plyometrics exercises and sprints with sled towing. In the first and second sessions, body composition, agility, power, and aerobic capacity were assessed. At the third session, countermovement jumps (CMJ) were performed with 1, 3, and 5 minutes after the execution of the CA. Significant differences were found for CMJ height 1, 3, and 5 minutes after the CA compared with baseline values (3.58, 5.10, 5.48%, respectively). There was a significant positive correlation between the level of general physical fitness and PAP (CMJ height increase) 5 minutes after (r = 0.73). When the athletes were divided into groups with higher and lower physical fitness, the CA caused a significant increase in CMJ height in both groups, but a significant difference (p < 0.05) was observed at all times after PAP induction, with better performance in higher versus lower fitness level. The results suggest that plyometrics exercises associated with sled towing sprints as a CA result in an increase in CMJ performance in athletes and that physical fitness directly influences the PAP occurrence, with higher fit players demonstrating an enhanced PAP response.
#6 High Coenzyme Q10 Plasma Levels Improve Stress and Damage Markers in Professional Soccer Players During Competition
Reference: Int J Vitam Nutr Res. 2020 Jul 8;1-12. doi: 10.1024/0300-9831/a000659. Online ahead of print.
Authors: Ana Sánchez-Cuesta, Ana Belén Cortés-Rodríguez, Ignacio Navas-Enamorado, José Antonio Lekue, Toscana Viar, Martín Axpe, Plácido Navas, Guillermo López-Lluch
Summary: Ubiquinol, the reduced form of Coenzyme Q10 (CoQ10), is a key factor in bioenergetics and antioxidant protection. During competition, professional soccer players suffer from considerable physical stress causing high risk of muscle damage. For athletes, supplementation with several antioxidants, including CoQ10, is widely recommended to avoid oxidative stress and muscle damage. We performed an observational study of plasma parameters associated with CoQ10 levels in professional soccer players of the Spanish First League team Athletic Club de Bilbao over two consecutive seasons (n = 24-25) in order determine their relationship with damage, stress and performance during competition. We analyzed three different moments of the competition: preterm, initial phase and mid phase. Metabolites and factors related with stress (testosterone/cortisol) and muscle damage (creatine kinase) were determined. Physical activity during matches was analyzed over the 2015/16 season in those players participating in complete matches. In the mid phase of competition, CoQ10 levels were higher in 2015/16 (906.8 ± 307.9 vs. 584.3 ± 196.3 pmol/mL, p = 0.0006) High levels of CoQ10 in the hardest phase of competition were associated with a reduction in the levels of the muscle-damage marker creatine kinase (Pearsons' correlation coefficient (r) = - 0.460, p = 0.00168) and a trend for the stress marker cortisol (r = -0.252, p = 0.150). Plasma ubiquinol was also associated with better kidney function (r = -0.287, p = 0.0443 for uric acid). Furthermore, high CoQ10 levels were associated with higher muscle performance during matches. Our results suggest that high levels of plasma CoQ10 can prevent muscle damage, improve kidney function and are associated with higher performance in professional soccer players during competition.
#7 Identification of Ankle Injury Risk Factors in Professional Soccer Players Through a Preseason Functional Assessment
Reference: Orthop J Sports Med. 2020 Jun 24;8(6):2325967120928434. doi: 10.1177/2325967120928434.
Authors: Lucas Sartori Manoel, Marcela Godoy Xixirry, Thabata Pasquini Soeira, Marcelo Camargo Saad, Marcelo Riberto
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7315686/pdf/10.1177_2325967120928434.pdf
Summary: Etiologically, the risk of an ankle injury depends on extrinsic and intrinsic factors, such as muscle strength asymmetry, decreased flexibility, and decreased proprioception, as well as patient age and history of injuries. The purpose of this study was to identify risk factors present in the preseason assessment that may predispose professional soccer players to ankle injuries. We hypothesized that analysis of these parameters could relate the incidence of injuries to the deficits found during the preseason period, enabling the identification of risk factors to predict the occurrence of injuries. A total of 89 professional soccer athletes were evaluated in the preseason period; the evaluation included athlete history and anthropometric data collection, an isokinetic ankle evaluation, and functional tests: the Dorsiflexion Lunge Test and Y-Balance Test (YBT). The athletes were monitored during the competitive period, and the incidence of injuries was surveyed. The association of quantitative variables and injury outcomes was analyzed using the Student t test for independent samples, with P < .05. For the association of categorical variables and injury outcomes, the chi-square test was performed, with P < .05. A higher incidence of ankle injuries was associated with lower YBT scores in the dominant (P = .04) and nondominant (P = .01) limbs. A higher body mass index was also associated with a higher injury occurrence (P = .01).
Functional tests, such as the YBT, are indicated tools for assessing the physical capacities and possible risks of ankle sprains, as they can evaluate the ankle functional capacity in a complex way, identifying athletes more prone to ankle injuries. Athletes' body mass index should also be taken into account to prevent such injuries.
#8 Effects of Different Solutions Consumed During Exercise on Cognitive Function of Male College Soccer Players
Reference: J Exerc Sci Fit. 2020 Sep;18(3):155-161. doi: 10.1016/j.jesf.2020.06.003. Epub 2020 Jun 20.
Authors: Feng-Hua Sun, Simon B Cooper, Frank Chak-Fung Tse
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7330616/pdf/main.pdf
Summary: The present study aimed to investigate the effects of three solutions, i.e. carbohydrate-electrolyte-solution (CES), carbohydrate-electrolyte-protein-solution (CEPS), and placebo (PLA), on cognitive function of college soccer players. Sixteen male college soccer players completed three main trials in a randomized cross-over study design. In each main trial, participants completed 90 min Loughborough Intermittent Shuttle Test (LIST) protocol and consumed one of three solutions. The cognitive function tests were performed; blood glucose and lactate concentrations, and several subjective measurements were also recorded in each trial. Compared with pre-exercise level, the accuracy of Rapid Visual Information Processing test (RVIPT) and the response time in Visual Search Test (VST, complex level) after LIST improved in CES and CEPS trials, but not in PLA trial. However, the accuracy of VST (complex level) decreased in both CES and CEPS trials, compared with PLA trial. CEPS consumption improved accuracy in VST (simple level), compared with CES consumption. Blood glucose concentrations were well maintained in CEPS trial, but not in CES and PLA trials. It seems that both CES and CEPS consumption show certain benefits on some aspects of cognitive function in male college soccer players in Hong Kong. However, these effects may be specific to the cognitive domain tested.
#9 Youth Soccer Parents' Attitudes and Perceptions About Concussions
Reference: J Adolesc Health. 2020 Jul 4;S1054-139X(20)30218-4. doi: 10.1016/j.jadohealth.2020.04.029. Online ahead of print.
Authors: Sungwon Kim, Daniel P Connaughton
Download link: https://www.jahonline.org/article/S1054-139X(20)30218-4/pdf
Summary: Parents are important figures in properly managing youth sport concussions. Although media attention has predominantly centered on concussions in contact/collision sports, evidence suggests that the concussion rate in soccer is comparable to those found in contact/collision sports. Given the high rate of concussions in youth soccer, this study aimed to examine parents of youth soccer athletes' attitudes and perceptions about concussions and associated factors. A cross-sectional study was conducted by surveying parents of youth soccer athletesfrom the five largest organized youth soccer programs across the U.S. The researchers developed a questionnaire after an extensive literature review and by modifying previously used instruments. Overall, 419 parents completed the survey. The vast majority (85%) agreed that a concussion is a serious injury, but only 27.9% believed that their child could suffer a concussion during the next season. Parents were most concerned about permanent brain damage when their child suffers a concussion. The vast majority (4.37 ± .89) perceived concussion reporting as an important injury prevention strategy. Greater appreciation and perceived risk about concussions was found particularly among parents who received concussion education and those who had witnessed or heard about a concussive incidence(s). Findings suggest that youth soccer parents have high appreciation and perceived risk about concussions. However, the need for more targeted education was noted, as improvements to better manage and reduce concussions can be made. Future research should continue examining youth sport parents' belief and understanding about concussions as well as factors affecting them.
#10 Fatigue Increases in Resting Muscle Oxygen Consumption After a Women's Soccer Match
Reference: Int J Sports Med. 2020 Jul 7. doi: 10.1055/a-1177-0849. Online ahead of print.
Authors: Aldo Alfonso Vasquez Bonilla, Rafael Timon, Alba Camacho-Cardeñosa, Marta Camacho-Cardeñosa, Samantha Guerrero, Guillermo Olcina
Summary: Currently, near infrared spectroscopy has a clear potential to explain the mechanisms of fatigue by assessing muscle oxygenation. The objective of the study was to observe the changes in muscle oxygen consumption after an official women's soccer match. The sample was 14 players who competing in the second division of Spain of women's soccer. They were evaluated before, immediately after and 24 h after the official match. Biochemical parameters were measured in blood plasma (BUN, GOT, LDH, CPK). The jumping in countermovement, perceived exertion and perceived muscle pain were also assessed. The muscle oxygen consumption and muscle oxygen saturation were evaluated in the gastrocnemius muscle with an arterial occlusion test. ANOVA of repeated measures, Pearson's correlation and Hopkins' statistics were applied to measure the magnitudes of change and effect size. There was observed an increase in kinetics of SmO2 at 24 h after the official match, using arterial occlusion. In addition, it was found that the increase in muscle oxygenation correlated with fatigue indicators, such as the increases in LDH, perceived muscle pain and the decrease in countermovement. It is confirmed that a women's soccer match produced an increase of resting muscle oxygenation in 24 h after the official match.
The aim of the study was to provide seasonal internal and external training load includig the Hooper Index in elite soccer players during an in-season period.
As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases.
Following studies were retrieved for this week:
#1 Effects of Three Different Stretching Protocols on Hamstring Muscle Flexibility in Professional Soccer Players: A Randomized Study
Reference: J Sports Med Phys Fitness. 2020 Jul;60(7):999-1004. doi: 10.23736/S0022-4707.20.10562-0.
Authors: Vincenzo Manzi, Ferdinando Iellamo, Anas R Alashram, Rosario D'onofrio, Elvira Padua, Maurizio Casasco, Giuseppe Annino
Summary: The current study aimed to investigate and compare the influences of global postural rieducation techniques (GPR), stretching exercises on a whole-body vibration platform (WBV), and static stretching exercises on hamstrings flexibility in elite soccer players. 24 professional soccer players were randomly assigned to either global postural re-education (N.=8), stretching on whole-body vibration group (N.=8) or static stretching (N.=8), during the first 4 weeks of the precompetitive season. Assessment of hamstring muscle flexibility was performed using a straight leg raise test. All participants were assessed three times: at baseline, at the end of the study protocol and 14 days after the end of the study protocol. The short-term increase in hamstring muscle flexibility was observed in all 3 groups, without significant differences among groups. However, after 14 days from the end of the interventions only the WBV group maintained the flexibility level achieved just at the end of the protocol with no significant changes in both legs whereas a significant decrease in the SLRT in GPR and SS groups, in right and left legs (GPR, P=0.002; P=0.015; SS, P=0.0001; P=0.0001), was observed. These results would suggest that GPR, static stretching on whole-body vibration and static stretching techniques all improve hamstring muscle flexibility, but only stretching on WBV maintains the effect over time in professional soccer players.
#2 Soccer Player With Unusual Right Shoulder and Arm Pain and Swelling
Reference: J Prim Health Care. 2020 Jun;12(2):181-183. doi: 10.1071/HC19101.
Authors: Alan Zakaria , Jasper Gill, Livia Maruoka Nishi, Jeff Nadwodny, George G A Pujalte
Summary: Paget-Schroetter syndrome, or effort thrombosis, refers to a deep venous thrombosis in an upper extremity. It is most commonly located in the axillary or subclavian veins and is associated with vigorous repetitive movements and anatomic abnormalities. This case study describes an 18-year-old Division 1 soccer player who presented with worsening axillary swelling and pain. He was found to have subclavian stenosis at the level of the thoracic inlet between the clavicle and first rib, with deep venous thrombosis in his right axillary, subclavian, proximal brachial, and basilic veins. It was diagnosed with ultrasound and confirmed with venography. He was treated initially with enoxaparin and warfarin before having mechanical thrombolysis, balloon venoplasty, infusion of tissue plasminogen activator, and a right first rib resection. CONCLUSION As Paget-Schroetter syndrome is rare, early recognition and management leads to fewer long-lasting sequelae and less morbidity. Left untreated, it can result in pulmonary embolism and residual upper extremity obstruction.
#3 Variations of Estimated Maximal Aerobic Speed in Children Soccer Players and Its Associations With the Accumulated Training Load: Comparisons Between Non, Low and High Responders
Reference: Physiol Behav. 2020 Jun 25;224:113030. doi: 10.1016/j.physbeh.2020.113030. Online ahead of print.
Authors: Filipe Manuel Clemente, Ana Filipa Silva, Ana Ruivo Alves, Pantelis Theodoros Nikolaidis, Rodrigo Ramirez-Campillo, Ricardo Lima, Mustafa Sö?üt, Thomas Rosemann, Beat Knechtle
Summary: The aim of this study was twofold: (i) to examine the variations of estimated maximal aerobic speed between non, low and high responders and (ii) to analyze the relationships between accumulated training load parameters and variations of maximal aerobic speed in children soccer players. Forty-four male soccer players were assessed three times during the early and mid-season (second to fifth month of the season) and were monitored daily over the period of analysis using the rating of perceived exertion (RPE), recording the training duration (in min) and calculating the session-RPE (sRPE). Pairwise comparisons revealed that maximal aerobic speed (MAS) was greater for the third assessment than the first (p-value [p] = 0.003; standardized effect of Cohen [d] = 0.355) and second (p = 0.013; d = 0.193) assessments. Large correlations were found between MAS and accumulated RPE, accumulated time, and accumulated sRPE. Moreover, non, low and high responders differed in ?MAS (p<0.001) with the last group presenting the largest improvement in MAS. Results suggest that children with lower MAS baseline levels will improve more this capacity over the early and mid-season period compared to children with better baseline levels. Moreover, associations between accumulated training load and MAS were found, suggesting that the training effort can be related with aerobic capacity changes.
#4 Association Between the ACE I/D Polymorphism and Muscle Injuries in Italian and Japanese Elite Football Players
Reference: J Sports Sci. 2020 Jul 2;1-7. doi: 10.1080/02640414.2020.1787683. Online ahead of print.
Authors: Myosotis Massidda, Eri Myamoto-Mikami, Hiroshi Kumagai, Hayato Ikeda, Yu Shimasaki, Masafumi Yoshimura, Paolo Cugia, Francesco Piras, Marco Scorcu, Naoki Kikuchi , Carla Maria Calò, Noriyuki Fuku
Summary: ACE I/D polymorphism has been recently associated with the susceptibility to inflammation and muscle damage after exercise. The aim of this study was to understand the association between the ACE I/D polymorphism and muscle injuries in a large cohort of elite football players from two different countries. Seven hundred and ten male elite football players from Italy (n = 341) and Japan (n = 369) were recruited for the study. Genomic DNA was extracted from either the buccal epithelium or saliva using a standard protocol. Structural-mechanical injuries and functional muscle disorders were recorded from 2009 to 2018. A meta-analysis was performed using Review Manager 5.3.5. In the Japanese cohort, the ACE I/D polymorphism was significantly associated with muscle injury using the D-dominant model (OR: 0.48, 95% CI: 0.24-0.97, P = 0.040). The meta-analysis showed that in the pooled model (Italian and Japanese populations), the frequencies of the DD+ID genotypes were significantly lower in the injured groups than in non-injured groups (OR: 0.61, 95% CI: 0.38-0.98, P = 0.04) with a low degree of heterogeneity (I2 = 0%). Our findings suggest that the ACE I/D polymorphism could influence the susceptibility to developing muscle injuries among football players.
#5 Effects of Daily Probiotics Supplementation on Anxiety Induced Physiological Parameters among competetive Football Players
Reference: Nutrients. 2020 Jun 29;12(7):E1920. doi: 10.3390/nu12071920.
Authors: A M G C P Adikari, Mahenderan Appukutty, Garry Kuan
Download link: https://www.mdpi.com/2072-6643/12/7/1920
Summary: Competitive football players who undergo strenuous training and frequent competitions are more vulnerable to psychological disorders. Probiotics are capable of reducing these psychological disorders. The present study aimed to determine the effect of daily probiotics supplementation on anxiety induced physiological parameters among competitive football players. The randomized, double-blinded, placebo-controlled trial was conducted on 20 male footballers who received either probiotics (Lactobacillus Casei Shirota strain 3 × 1010 colony forming units (CFU) or a placebo drink over eight weeks. Portable biofeedback devices were used to measure the electroencephalography, heart rate, and electrodermal responses along with cognitive tests at the baseline, week 4, and week 8. Data were statistically analyzed using mixed factorial ANOVA and results revealed that there is no significant difference between the probiotic and placebo groups for heart rate (61.90 bpm ± 5.84 vs. 67.67 bpm ± 8.42, p = 0.09) and electrodermal responses (0.27 µS ± 0.19 vs. 0.41 µS ± 0.12, p = 0.07) after eight weeks. Similarly, brain waves showed no significant changes during the study period except for the theta wave and delta wave at week 4 (p < 0.05). The cognitive test reaction time (digit vigilance test) showed significant improvement in the probiotic group compared to the placebo (p < 0.05). In conclusion, these findings suggest that daily probiotics supplementation may have the potential to modulate the brain waves namely, theta (relaxation) and delta (attention) for better training, brain function, and psychological improvement to exercise. Further research is needed to elucidate the mechanism of current findings.
#6 Injuries and Functional Performance Status in Young Elite Football Players: A Prospective 2-year Monitoring
Reference: J Sports Med Phys Fitness. 2020 Jun 30. doi: 10.23736/S0022-4707.20.10886-7. Online ahead of print.
Authors: Johanna Sieland, Frieder Krause, Kristin Kalo, Jan Wilke, Lutz Vogt, Winfried Banzer, Daniel Niederer
Summary: Motor function, such as strength asymmetries of the lower extremities and impaired dynamic stability, have a predictive value for the risk of injury. The present study aimed to reveal potential associations between injury and motor performance. Two hundred five (205) male youth elite (association) football (soccer) players (mean ± standard deviation: 13.5 ± 4.5 years, 57.2 ± 30.2 kg, 168 ± 35 cm) were included. A test battery was conducted twice per season, over two consecutive seasons (four times). Mobility (Sit and Reach Test, SnR), dynamic stability (Single Leg Hop for Distance, SLHD), linear sprinting speed (10 m, 30 m [s]), agility (Zig-Zag test with and without dribbling a ball [s]), jump performance (Counter Movement Jump (CMJ) and Drop Jump (DJ) [cm]) and Maximal Isometric Voluntary Force (MIVF [N]) of the knee extensors and flexors were assessed. All injuries occurring over the two-year period, as well as training and competition exposure time, were collected and used as grouping variables for statistical difference testing. One hundred twenty five (125) injuries in 93 players occurred (an injury incidence of 2.7/1000 hours of exposure). Age was associated with injury incidence (r=.191; p=.006). Neither DJ, CMJ, SnR nor agility performance were statistically different between injured and non-injured participants (p>.05). Group differences did occur for sprint and strength (p=.011; p=.016), but these lapsed after the inclusion of age as a covariate. Only for SLHD symmetry was a non-significant trend evident after the correction for age (p=.08). The occurrence of musculoskeletal injuries in junior football players are, probably, not related to baseline motor function. Group differences between injured and non-injured youth elite football players are mostly explained by age. Only the symmetry in SLHD could be a potential risk factor for injuries and merits further investigation.
#7 Cross-Cultural Exploration of Baseline ImPACT Quick Test Performance Among Football Athletes in Zambia
Reference: Phys Sportsmed. 2020 Jun 30. doi: 10.1080/00913847.2020.1790983. Online ahead of print.
Authors: Jessica Wallace, Philip Schatz, Davie Mulenga, Mark Lovell, Gabriel Muyinda, Kachinga Agrippa Sichizya, Joseph Mulenga, Tracey Covassin
Summary: Concussion is a global sport injury; however, this public health issue has yet to be studied across Africa. It is unknown if tests such as the Immediate Post-Concussion Assessment and Cognitive Test (ImPACT) Quick Test (QT) are culturally appropriate for implementation as part of a concussion screening protocol in Zambia or other African nations. Study objectives included: 1) establish that Zambian athletes are able to complete the iPad-based ImPACT QT with respect to language or cultural barriers that may exist, and 2) document baseline neurocognitive percentile ranks among Zambian football athletes on the ImPACT QT. This study was completed with adult premiere league football athletes in Zambia (n=125) aged 24.48±5.41. Participants completed the ImPACT QT neurocognitive assessment prior to a preseason practice. Outcome measures were average performance on 3 factor scores: Motor Speed, Memory, and Attention Tracker, presented as percentile ranks using normative data built-into the ImPACT QT. Zambian athletes scored nearly two standard deviations below the mean on Motor Speed (7th percentile), using North American normative data. However, performance on Attention Tracker (44th percentile) and Memory (56th percentile) was within the average range. Results of the current study show that Zambian athletes are able to complete the ImPACT QT, despite any language or cultural differences that may exist. In addition, preliminary percentile ranks suggest Zambian football athletes have average scores on Attention and Memory and below average scores on Motor Speed. These data are the first to explore Zambian athletes' performance on a cognitive concussion measure.
#8 Age-related and Training-Induced Changes in Morphological Characteristics of Young Elite Male Soccer Players
Reference: J Sports Med Phys Fitness. 2020 Jun 30. doi: 10.23736/S0022-4707.20.11119-8. Online ahead of print.
Authors: Nikolaos Androulakis, Nikolaos Koundourakis, Christos Tsiakiris, George Notas
Summary: In soccer, morphological characteristics of young players are particularly important as they have a significant impact on the performance of many technical-tactical elements. Our aim in this study was to investigate whether soccer specific training on its own or combined with strength training can influence the morphological characteristics, of young soccer players and if so, to establish which age is more appropriate for interventions through individualized training. The study sample consisted of 61 young male soccer players, members of two under 17 (U171 and U172) and two under 19 (U191 andU192) teams. U171 (n= 17, consists of ages: 15.1±0.6) and U191 (n=14, consists of ages 17.3±0.5 years) teams performed only soccer specific training whilst U172 (n= 18, consists of ages 15.0±0.4 years) and U192 (n=12 consists of ages 17.1±0.7 years) teams had two extra strength trainings per week. Anthropometric measurements were performed at the beginning and at the end of the 10-months session. Lean body mass was increased whilst body fat decreased at the end of the study in all teams (p<0.001). No significant changes were found regarding endomorphic and ectomorphic outcome. Mesomorphic outcome was significantly increased only in U172 team (p<0.001). Our data supports that earlier interventions (between ages 15-17 years) in the training routine may be more effective in order to achieve anatomical and morphological characteristics most favorable for soccer.
#9 Design and Validation of the Instrument for the Measurement of Learning and Performance in Football
Reference: Int J Environ Res Public Health. 2020 Jun 27;17(13):E4629. doi: 10.3390/ijerph17134629.
Authors: Juan M García-Ceberino, Antonio Antúnez, Sergio J Ibáñez, Sebastián Feu
Download link: https://www.mdpi.com/1660-4601/17/13/4629/pdf
Summary: The assessment of tactical-technical knowledge of football is essential to develop optimal and integral teaching processes for students. Therefore, the aim of this study was to design and validate an instrument so that teachers, coaches, and researchers can observe and codify both the tactical behaviors and technical skills performed by the students in the game of football. The design and validation of the instrument were carried out in four phases: a) review of the literature and previous instruments; b) design of the Instrument for the Measurement of Learning and Performance in Football (IMLPFoot). It assesses all the offensive and defensive play actions, with and without the ball, as well as their three components (decision-making, technical execution, and final result); c) sample selection of experts (N = 12); and d) quantitative (Likert-type scale from 1 to 10) and qualitative assessment of degree the pertinence, unambiguity, and importance of each of the 33 items included in the IMLPFoot. Aiken's V coefficient was used to determine content validity. Likewise, internal consistency was calculated using Cronbach's ? coefficient. The results showed demanding levels of validity (V ? 0.77), internal consistency (? = 0.983), inter-rater, and intra-rater reliability. Therefore, it is a valid and reliable instrument that makes possible a complete assessment of football in physical education classes and/or in the sports context (out-of-school football).
Player readiness can affect the ability to perform and tolerate prescribed training load. Consequently, practitioners need objective evidence to inform readiness to train.
The purpose was to quantify the relationship between daily training load and a range of potential measures of fatigue.
Following studies were retrieved for this week:
#1 A Case Study Comparison of Objective and Subjective Evaluation Methods of Physical Qualities in Youth Soccer Players
Reference: J Sports Sci. 2020 Jun 13;1-9. doi: 10.1080/02640414.2020.1766177. Online ahead of print.
Authors: James H Dugdale, Dajo Sanders, Tony Myers, A Mark Williams, Angus M Hunter
Summary: Subjective and objective assessments may be used congruently when making decisions regarding player recruitment in soccer, yet there have been few attempts to examine the level of agreement between these methods. Therefore, we compare levels of agreement between subjective and objective assessments of physical qualities associated with youth soccer performance. In total, 80 male youth soccer players (13.2 ± 1.9 years), and 12 professional coaches volunteered to participate. Players were objectively assessed using five fitness measures: Yo-Yo Intermittent Recovery Test Level 1; Countermovement vertical jump; Functional Movement Screen™; 5/20 m sprint; alongside anthropometric measures. Additionally, coaches subjectively rated each player on the same five physical qualities using 5-point Likert scales. Inter-rater agreement between ratings from lead and assistant coaches was established for each age group. Moreover, Bayesian regression models were fitted to determine how well coach ratings were able to predict fitness test performance. Although inter-rater agreement between lead and assistant coaches was moderate-to-substantial (ω = 0.48-0.68), relationships between coaches subjective rating's and corresponding fitness test performance were only highly related for the highest and lowest performing players. We suggest that while ratings derived from objective and subjective assessment methods may be related when attempting to differentiate between distinct populations, concerns exist when evaluating homogeneous samples using these methods. Our data highlight the benefits of using both types of measures in the talent identification process.
#2 Recommendations for Initial Examination, Differential Diagnosis and Management of Concussion and Other Head Injuries in High-Level Football
Reference: Scand J Med Sci Sports. 2020 Jun 17. doi: 10.1111/sms.13750. Online ahead of print.
Authors: Nina Feddermann-Demont, Georges Chiampas, Charlotte M Cowie, Tim Meyer, Anna Nordström, Margot Putukian, Dominik Straumann, Efraim Kramer
Summary: Head injuries can result in substantially different outcomes, ranging from no detectable effect to transient functional impairments to life-threatening structural lesions. In high-level international football (soccer) tournaments, on average, one head injury occurs in every third match. Making the diagnosis and determining the severity of a head injury immediately on-pitch or off-field is a major challenge for team physicians, especially because clinical signs of a brain injury can develop over several minutes, hours or even days after the injury. A standardised approach is useful to support team physicians in their decision whether the player should be allowed to continue to play or should be removed from play after head injury. A systematic, football-specific procedure for examination and management during the first 72 hours after head injuries and a graduated Return-to-Football programme for high-level players has been developed by an international group of experts based on current national and international guidelines for the management of acute head injuries. The procedure includes seven stages from the initial on-pitch examination to the graduated Return-to-Football programme. Details of the assessments and the consequences of different outcomes are described for each stage. Criteria for emergency management (red flags), removal from play (orange flags), and referral to specialists for further diagnosis and treatment (persistent orange flags) are provided. The guidelines for Return-to-Sport after concussion-type head injury are specified for football. Thus, the present paper presents a comprehensive procedure for team physicians after a head injury in high-level football.
#3 Position Statement of the Royal Spanish Football Federation for the Resumption of Football Activities After the COVID-19 Pandemic (June 2020)
Reference: Br J Sports Med 2020 Jun 16;bjsports-2020-102640. doi: 10.1136/bjsports-2020-102640. Online ahead of print.
Authors: Helena Herrero-Gonzalez, Rafael Martín-Acero, Juan Del Coso, Carlos Lalín-Novoa, Rafel Pol, Pilar Martín-Escudero, Ana Isabel De la Torre, Christopher Hughes, Magni Mohr, Francisco Biosca, Rafael Ramos
Download link: https://bjsm.bmj.com/content/bjsports/early/2020/06/15/bjsports-2020-102640.full.pdf
#4 The Effects of High-Intensity Interval Training (HIIT) in Improving VO2 Max
Reference: Enferm Clin. 2020 Jun;30 Suppl 4:507-511. doi: 10.1016/j.enfcli.2019.10.130.
Authors: Dilli Dwi Kuswoyo, Jori Lahinda, Syamsudin
Summary: This study aims to determine the effect of High-Intensity Interval Training (HIIT) in improving VO2 Max in Football Students Activity Unit, University of Musamus. This research is an experimental study with one group pretest and posttest design research. The population in this study was Football Students Activity Unit, the University of Musamus, which numbered 22 students who were the subjects of the study. Data retrieval technique is by tests and measurements. The instrument used is a multi-stage fitness test (bleep test). The students were given HIIT; it carried out twice a week for four weeks. Analysis of the data used is using t-test at 0.05% as the significance level. Based on the results, the number of pretests showed on 39.6773. While at the posttest after there was an improvement, the number showed on 48.5863. Based on the results of data analysis on the hypothesis in the study, it was found that there was a significant effect of HIIT in improving VO2 Max football student activity unit, University of Musamus, it was indicated by the score of t-count that higher than t-table (13.015>2.080). There was a significant effect of the HIIT in improving football students' VO2 of Max at University of Musamus.
#5 Prior Workload Has Moderate Effects on High-Intensity Match Performance in Elite-Level Professional Football Players When Controlling for Situational and Contextual Variables
Reference: J Sports Sci. 2020 Jun 16;1-12. doi: 10.1080/02640414.2020.1778355. Online ahead of print.
Authors: Matthew Springham, Sean Williams, Mark Waldron, Anthony J Strudwick, Chris Mclellan, Robert U Newton
Summary: This investigation examined the effect of prior workload on high-intensity football match performance. Player load variables were recorded using a global positioning system and converted into composite variables: rolling season accumulated load (AL), exponentially weighted moving average acute, chronic and acute:chronic workload ratio (A:C). Match-play high-intensity performance-per-minute: accelerations (ACC), sprints, high-speed running (HSR) and high metabolic load (HMLd) distances; and situational and contextual variables were recorded for all games. Partial least squares modelling, and backward stepwise selection determined the most parsimonious model for each performance variable. Quadratic relationships of small to moderate effect sizes were identified for sprint AL and sprint performance, HSR AL and HSR performance, acute HMLd and HMLd performance, acute sprint load and ACC performance and A:C sprint load and ACC performance. Match performance was typically greatest between the mean and +1SD. High chronic HMLd, and combined acceleration and deceleration (ACC+DEC) load exerted small beneficial effects on HMLd and HSR performance, whereas high acute load exerted trivial to moderate negative effects. High sprint A:C exerted a small beneficial effect on sprint performance and playing position exerted small effects on HSR and HMLd performance. Prior workload has trivial to moderate effects on high-intensity match performance in professional players.
#6 Adapted Recreational Football Small Sided Games Improves Cardiac Capacity, Body Composition and Muscular Fitness in Patients With Type 2 Diabetes: Results From a Pilot Study
Reference: J Sports Med Phys Fitness. 2020 Jun 12. doi: 10.23736/S0022-4707.20.10498-5. Online ahead of print.
Authors: Annamaria Mancini, Anna A Turco, Carlo G Tocchetti, Georgios Ermidis, Francesca Cozzolino, Giacomo Campi, Paolo Parrella, Valentina Mercurio, Ciro G Mainolfi, Teresa Mannarino, Adriana D'antonio, Maurizio Marra, Rita Polito, Luca Russomando, Domenico Martone, Stefania Orrù, Aurora Daniele, Brunella Capaldo, Francesco Salvatore, Pasqualina Buono
Summary: The usefulness of adapted small-side games (SSGs) in improving cardiac function in subjects with T2DM is still debated. Here we evaluated the effects of 18weeks Indoor Muscular Activation training (6 wks; IMA) followed by adapted SSGs football training (12wks) on cardiac function, muscular fitness, Body Composition and adiponectin expression in sedentary T2DM volunteers. 6 T2DM patients underwent IMA protocol of 6 wks, 2/wk followed by 12 wks SSGs (5vs5; once a wk) training. Glucose, lipid profile and serum homocysteine concentration, Body Composition (BC), bone mineral density (DEXA), were determined at baseline and after 18wks (IMA+SSGs). VO2max and muscular fitness were recorded at baseline and after IMA (6wks) and SSGs (12 wks), respectively. No significant differences were found for VO2max and muscular fitness after 6wks of IMA. After 18wks (6 wks IMA+ 12 wks SSGs) of training, significant improvements were found in the following parameters: work capacity, VO2peack, Ventilation (VEpeack), breathing reserve consumption and oxygen uptake efficiency (OUES) (p<0.05); leg fitness (p<0.05), BC (p<0.05), vertebral column T-score (p<0.01) and adiponectin (total and High Molecular Weight, HMW; p<0.05). Compared to baseline, a reduction in serum homocystein (Hcy) occurred after 18 wks of training (p<0.05). We evidenced that weekly adapted SSGs friendly football matches for 12 weeks improve cardiorespiratory capacity and the expression of independent markers associated with cardiovascular risk in T2DM patients, suggesting an overall reduced CVD-risk in these patients. These preliminary data encourage us to test the efficacy of this type of exercise in a larger population.
#7 Physical Fitness and Activity Changes After a 24-week Soccer-Based Adaptation of the U.S Diabetes Prevention Program Intervention in Hispanic Men
Reference: Prog Cardiovasc Dis. 2020 Jun 27;S0033-0620(20)30135-3. doi: 10.1016/j.pcad.2020.06.012. Online ahead of print.
Authors: Jennifer K Frediani, Alan F Bienvenida, Jianheng Li, Melinda K Higgins, Felipe Lobelo
Summary: One third of the U.S. adult population is estimated to have prediabetes. Hispanics have a 50% higher type 2 diabetes (T2DM) death rate compared to non-Hispanic whites, yet low participation in lifestyle change programs, making this subgroup an important target for prevention efforts. The purpose of this study was to determine the effects of an exercise intervention implementing the Center for Disease Control and Prevention National Diabetes Prevention Program (NDPP) plus recreational soccer (RS) in Hispanic men. Overweight and obese Hispanic men, aged 30-57 years with prediabetes at screening were recruited from the community. Trained soccer coaches led 30-min facilitated discussion of the NDPP modules after each RS session, with two weekly sessions delivered over 12 wks, then once a wk until 24 wks. The 1-h RS sessions followed the Football Fitness curriculum structure. Standardized study assessments included objectively measured physical activity via fitness tracker, physical fitness via validated field tests, global positional system soccer specific metrics and behavior change questionnaires. Mixed models assessed the outcomes as a function of time and cohort and incorporated an unstructured covariance structure to examine the difference between baseline, 12 and 24 wks. All analyses were conducted as intent-to-treat and generated using SAS v 9.4. Hispanic males (n = 41; mean age 41.9 [6.2 SD] years) were obese at baseline (mean BMI 32.7, standard error [0.7]). After 24 wks of the NDPP+RS intervention, there were significant beneficial changes in vertical jump (2.8 [1.3] cm; p = 0.048), agility and lower extremity muscular power (figure 8-run) at 12 wks (-4.7% change; p = 0.001) and 24 wks (-7.2% change; p < 0.0001), predicted VO2 max (12 wks: 1.9%; p = 0.007; 24 wks 1.0%; p = 0.036), modified push-ups increased 22% (p < 0.0001) at 12 wks and 31% (p < 0.0001) at 24 wks, dynamic sit-ups increased 10% (p = 0.005) at 12 wks and 15% (p < 0.0001) at 24 wks. Among middle-aged Latino men, broad-ranging significant improvements in physical fitness were observed after 24 wks participating in lifestyle education plus RS in a single arm feasibility trial.
#8 Analysis of Physical and Technical Performance of Substitute Players in Professional Soccer
Reference: Res Q Exerc Sport. 2020 Jun 30;1-8. doi: 10.1080/02701367.2020.1755414. Online ahead of print.
Authors: Miguel Lorenzo-Martínez, Alexis Padrón-Cabo, Ezequiel Rey, Daniel Memmert
Summary: Current soccer scientific literature is scarce with regard to examining the technical performance of substitute players. This study aimed to analyze the physical and technical performance of substitute players versus those who completed the entire match or were replaced and also examine the performance of substitutes across different playing positions. The sample was composed of 6,631 match observations from 431 professional soccer players competing in the German Bundesliga during the season 2018-2019. These observations were divided into three groups: entire match (n = 3,807), replaced (n = 1,412), and substitutes (n = 1,412). Linear mixed models were adjusted to compare the performance of the three groups independently of playing position and separately for each position (central defenders, fullbacks, central midfielders, wide midfielders, and attackers). Substitute players showed higher total distance covered (effect sizes [ES]: 0.99-1.06), number of sprints (ES: 0.60-0.64), and number of fast runs (ES: 0.83-0.91) relative to playing time than replaced and entire match players. The differences in technical performance between groups varied according to playing position. Substitute central defenders showed less possession (ES: 0.39-0.41), touches (ES: 0.47-0.57), and passes (ES: 0.54-0.59) but higher defensive performance (ES: 0.51-0.54) than replaced and entire match players. Substitutes in midfield and attack positions displayed more possession (ES: 0.22-0.47), touches (ES: 0.27-0.37), and shots (ES: 0.22-0.28) than replaced and entire match players. This study has shown that substitutes are able to improve the performance of the players who completed the entire match or were replaced in both physical and some technical variables depending on playing position.
#9 Changes in Perceptions of Mental Fatigue During a Season in Professional under-23 English Premier League Soccer Players
Reference: Res Sports Med. 2020 Jun 30;1-11. doi: 10.1080/15438627.2020.1784176. Online ahead of print.
Authors: William Abbott, Thomas E Brownlee, Robert J Naughton, Tom Clifford, Richard Page, Liam D Harper
Summary: The present study assessed changes in academy soccer players' perception of mental fatigue (MF) across a competitive season, investigating the relationship between MF and other subjective measures of wellness. Ten players completed a modified Brief Assessment of Mood (BAM+) questionnaire that included the question: "How mentally fatigued do you feel"? on match-day (MD) and one (MD+1), two (MD+2) and three (MD+3) days post-match (35 matches). Players reported their MF, along with other subjective measures (sleep, muscle soreness, fatigue and motivation). Results found MF was elevated on MD+1 (43±1 mm) compared to all other days (all P≤0.001). Players reported lower MF on MD+1 in the late-season phase (34±2 mm) compared to both early- (50±2 mm, P≤0.001) and mid-season (46±2 mm, P≤0.001). This coincided with an 80%-win rate in the late-season phase versus the early- (33%) and mid-season (50%). There were very strong repeated-measures correlations between changes in MF and sleep (r=-0.77), muscle soreness (r=0.94), fatigue (r=0.92) and motivation (r=-0.89; all P ≤ 0.0005). In conclusion, MF was closely aligned to match success and other wellness variables. This data suggests a potential lack of sensitivity for identifying MF using a subjective questionnaire. Therefore, researchers and practitioners could work together to identify other ways of practically assessing MF.
#10 Evolution of Soccer as a Research Topic
Reference: Prog Cardiovasc Dis . 2020 Jun 26;S0033-0620(20)30134-1. doi: 10.1016/j.pcad.2020.06.011. Online ahead of print.
Authors: Donald T Kirkendall, James R Urbaniak
Summary: Soccer has not only the largest number of worldwide participants, it is also the most studied sport, with nearly 14,000 citations listed on Pubmed and nearly 60% more articles than the next most studied sport. Research about soccer was limited until the late 1970s when exponential growth began; approximately 98% of all soccer-related research publications have occurred since 1980. This vast repository of soccer research shows trends in various major (e.g., 'sex' or 'age group' or 'performance' or 'injury') and specialty (e.g., agility, deceleration, elbow-head impact injuries, behavior) topics. Examining trends of the various topics provides insights into which subjects have come in and out of favor as well as what topics or demographics have been neglected and worthy of inquiry. A further examination can be used by students to learn the most productive researchers, which programs have a strong history of inquiry, and what journals have demonstrated a commitment to publishing research on soccer.
The aim of this study was to analyse the effect of mental fatigue on passing decision-making in professional soccer athletes.
The results of a systematic review.
Following studies were retrieved for this week:
#1 Financial Awards and Their Effect on Football Players' Anxiety and Coping Skills
Reference: Front Psychol. 2020 Jun 10;11:1148. doi: 10.3389/fpsyg.2020.01148. eCollection 2020.
Authors: Adriana Kaplánová
Summary: Financial awards can be an important factor affecting athletes' mental preparation and various skills to manage stress. Since such a link has not yet been studied, the study has been designed to evaluate the moderation effect of financial awards in relation to football players' anxiety and coping skills. The study consists of 110 male football players aged 18-32 years old (mean ± SD: 23.98 ± 3.01 years) who were divided into two groups: financial awarded (n = 48) and financial unawarded for sports performance (n = 62). The anxiety of football players was measured by the Sport Anxiety Scale SAS-2. Coping strategies to manage stress were assessed by the Athletic Coping Skills Inventory ACSI-28. The effect of financial awards in relation to football players' anxiety and coping skills was evaluated by the mediators' model using the PROCESS software (Hayes, 2018). The results suggest that financial awards are important factors that influence football players' anxiety and coping skills. The financial awards increase the motivation of football players to better prepare for sports performance, which has been proven, through better setting of performance goals and more careful mental preparation. Financially awarded football players seem to respect the coach and follow his instructions to a greater extent than unawarded football players, which may be due to the financial benefits and the commitment they have confirmed by signing to the football club. In another aspect, the financial awards are likely to increase the cognitive trait of the anxiety of football players. It seems that financial players are more concerned about the failure of the match, which increases their anxiety, especially since it is a cognitive part and affects their sports performance. For this reason, we encourage sports organizations to focus more on the mental preparation of football players. It is important to provide football players the opportunity to graduate from short- or long-term mental training conducted by a trained sports psychologist not only at the time of the athlete's failure but also as a preventive measure against increasing cognitive anxiety. We recommend sports organizations to train coaches in the field of mental training, preferably through annual short training sessions with a sports psychologist, to influence the development of desirable athletes' coping skills.
#2 Effect of Weekly Training Frequency With the Nordic Hamstring Exercise on Muscle-Strain Risk Factors in Football Players: A Randomized Trial
Reference: Int J Sports Physiol Perform. 2020 Jun 24;1-8. doi: 10.1123/ijspp.2018-0780. Online ahead of print.
Authors: Thales M Medeiros, João B Ribeiro-Alvares, Carolina G Fritsch, Gabriel S Oliveira, Lucas Severo-Silveira, Evangelos Pappas, Bruno M Baroni
Summary: The purpose was to examine the differences between performing Nordic hamstring exercises once or twice a week on hamstring eccentric strength and other muscle-strain risk factors in high-level football players. In this randomized trial, 32 football players (18-23 y old) completed an 8-week Nordic hamstring exercise training program in 1 of 2 experimental groups: group 1 (once a week; n = 15) and group 2 (twice a week; n = 17). Knee-flexor/extensor peak torques and biceps femoris long-head muscle architecture were assessed through isokinetic dynamometry and ultrasonography, respectively, before and after the training programs. Analysis of covariance, effect sizes (ESs), and t tests for percentage change were used to assess the effect of the 2 interventions on the outcome measures. Group 2 demonstrated higher hamstring concentric peak torque than group 1 posttraining (155-164 vs 149-158 N·m; P = .043; ES = 0.27), although there was also a statistical trend for higher hamstring eccentric peak torque (212-234 vs 198-221 N·m; P = .098; ES = 0.37), hamstring-to-quadriceps conventional ratio (0.56-0.59 vs 0.54-0.57; P = .089; ES = 0.31), and hamstring-to-quadriceps functional ratio (0.76-0.84 vs 0.71-0.79; P = .076; ES = 0.50). No between-groups differences were found for muscle thickness (P = .864; ES = 0.12), pennation angle (P = .289; ES = 0.18), fascicle length (P = .406; ES = 0.03), and quadriceps concentric peak torque (P = .340; ES = 0.02). Only the Nordic hamstring exercise training program performed twice a week strengthened the hamstrings of high-level football players, while similar changes in muscle architecture occurred with both once- and twice-weekly sessions.
#3 Football Can Tackle Type 2 Diabetes: A Systematic Review of the Health Effects of Recreational Football Practice in Individuals With Prediabetes and Type 2 Diabetes
Reference: Res Sports Med. 2020 Jun 22;1-19. doi: 10.1080/15438627.2020.1777417. Online ahead of print.
Authors: Ana Barbosa, João Brito , Pedro Figueiredo, André Seabra, Romeu Mendes
Summary: This work aimed to summarize the health effects of recreational football practice in individuals with prediabetes and type 2 diabetes (T2D), through a systematic review. An electronic search was performed in PubMed, Scopus, Web of Science, LILACS and list of references of the available reviews, until July 2019. Studies were eligible if they included any form of football practice, in patients diagnosed with prediabetes or T2D. After recreational football practice, participants with prediabetes or T2D improved fasting glucose, total and LDL cholesterol, triglycerides, body mass, body fat percentage, waist circumference, blood pressure, and maximal oxygen uptake. Further benefits were found in fat-free mass and resting heart rate for participants with prediabetes, and in glycated haemoglobin, body mass index and fat mass in individuals with T2D. This systematic review showed promising benefits of recreational football practice on both the prevention and control of T2D and related cardiovascular risk.
#4 Ankle Osteoarthritis and Its Association With Severe Ankle Injuries, Ankle Surgeries and Health-Related Quality of Life in Recently Retired Professional Male Football and Rugby Players: A Cross-Sectional Observational Study
Reference: BMJ Open. 2020 Jun 21;10(6):e036775. doi: 10.1136/bmjopen-2020-036775.
Authors: Liam D A Paget, Haruhito Aoki, Simon Kemp, Mike Lambert, Clint Readhead, Keith A Stokes, Wayne Viljoen, Gustaaf Reurink, Johannes L Tol, Gino M M J Kerkhoffs, Vincent Gouttebarge
Download link: https://bmjopen.bmj.com/content/bmjopen/10/6/e036775.full.pdf
Summary: The objective was to determine (1) the prevalence of ankle osteoarthritis (OA) among former professional football and rugby players, (2) assess the association between ankle injuries or ankle surgeries with ankle OA, and (3) compare the mental and physical quality of life (QoL) between former professional football and rugby players with and without OA. We conducted a questionnaire-based observational study with a cross-sectional design. Former professional football and rugby players were recruited by the Football Players Worldwide and the International Rugby Players. Information concerning ankle OA, sustained ankle injuries and ankle surgeries was gathered (medical record or most recent medical professional). Health-related QoL was assessed using the Patient-Reported Outcomes Measurement Information System (PROMIS) physical and mental health scores. Overall, 553 former professional football (n=401) and rugby (n=152) players were enrolled in the study (response rate of 56%). Ankle OA prevalence among former professional football and rugby players was 9.2% and 4.6%, respectively. Football players were more likely to suffer from ankle OA following every ankle injury and/or surgery. Football and rugby players with ankle OA had similar PROMIS physical and mental health scores to the norm for the general population. Former professional football and rugby players had higher ankle OA prevalence than the general population (3.4%). Football players are more likely to suffer from ankle OA following every ankle injury and/or surgery. No clinically relevant difference was seen for physical or mental health-related QoL among football and rugby players. Preventive measures for ankle injuries are recommended.
#5 Medial Epicondyle Avulsion After Elbow Dislocation in an Adolescent Non-Professional Soccer Player Treated With a Cannulated Screw: A Case Report
Reference: Acta Biomed. 2020 May 30;91(4-S):271-275. doi: 10.23750/abm.v91i4-S.9578.
Authors: Alessio Pedrazzini, Alberto Visigalli, Piergiulio Valenti, Nicola Bertoni, Henry Yewo Simo, Roberto Bisaschi, Vanni Medina, Bianca Pedrabissi, Francesco Ceccarelli, Francesco Pogliacomi
Summary: Medial epicondyle fractures of the humerus account for 11-20% of all elbow injuries in children and in 30-55% of cases they are associated with an elbow dislocation. Undisplaced fractures are usually treated conservatively but literature is controversial regarding the treatment of displaced fractures (≥5mm) in paediatric fractures. In recent years, there is an emerging consensus that such patients may benefit more from open reduction and internal fixation. Authors report a case of a 15 years old nonprofessional soccer player who suffered of an elbow dislocation with an intra-articular fragment derived from avulsion of the medial epicondyle. Clinical and instrumental evaluation confirmed elbow dislocation with an intra-articular fragment derived of the medial epicondyle. After the reduction an open reduction and internal fixation with cannulated screw was performed. Clinical evaluation after 90 days showed resolution of pain and almost complete ROM and complete recovery of strength and of functionality of the operated limb. Furthermore, x-rays demonstrated consolidation of the fracture. this case confirms that a precise evaluation of the fracture and its displacement is at the base of satisfactory outcomes. If fracture is displaced≥5mm and patient is near skeletal maturity open reduction and fixation is indicated.
#6 Long-term Test-Retest Evaluation of the King-Devick Test in Youth Soccer Athletes
Reference: J Neurol Sci. 2020 Jun 6;416:116951. doi: 10.1016/j.jns.2020.116951. Online ahead of print.
Authors: Abigail C Bretzin, Morgan Anderson, Ryan N Moran, Tracey Covassin
Summary: Despite the clinical utility of baseline comparisons during concussion assessments, little evidence exists on long-term test-retest reliability of baseline tests in youth athletes. In addition, sex differences in baseline performance are inconsistent in youth athletes, warranting further research. The purpose was to examine sex differences, prevalence of false-positive scores, and long-term test-retest reliability of the King-Devick (KD) test. Healthy youth athletes (23 males, 28 females) completed the KD test prior to the Spring 2016 and Fall 2017 seasons. Two-way random-effects intraclass correlation coefficients (ICCs) were utilized to determine test-retest reliability. A mixed between-within ANOVA with post-hoc t-tests were used to identify the interaction between sex and season, and frequencies were used to determine abnormal test score prevalence. The KD test demonstrated good test-retest reliability (0.77[95% CI, 0.43-0.89]), with 11.8% of youth athletes having clinically meaningful improvements between Season 1 to Season 2. There was a significant sex*season interaction (F(1,49) = 4.67, p = .04), with significantly greater improvements between seasons in male youth athletes compared to female youth athletes. However, 33-35% of youth athletes displayed abnormal test scores in Season 2 relative to Season 1. The KD test demonstrated good reliability and only a small percentage had clinically meaningful changes, however a high prevalence of false-positive scores were observed in this sample.
#7 Match Demands of Women's Collegiate Soccer
Reference: Sports (Basel). 2020 Jun 12;8(6):E87. doi: 10.3390/sports8060087.
Authors: Andrew R Jagim, Jason Murphy, Alexis Q Schaefer, Andrew T Askow, Joel A Luedke, Jacob L Erickson, Margaret T Jones
Download link: https://www.mdpi.com/2075-4663/8/6/87/pdf
Summary: Research describing the match and specific positional demands during match play in women's collegiate soccer is limited. The purpose of the study was to quantify the match demands of National Collegiate Athletic Association (NCAA) Division III soccer and assess position differences in movement kinematics, heart rate (HR), and energy expenditure. Twenty-five Division III women soccer players (height: 1.61 ± 0.3 m; body mass: 66.7 ± 7.5 kg; fat-free mass: 50.3 ± 6.5 kg; body fat%: 25.6 ± 5.1%) were equipped with a wearable global positioning system to assess the demands of 22 matches throughout a season. Players were categorized by position (goal keepers (GK), center defenders (CB), flank players (FP), forwards (F), and center midfielders (CM)). Players covered 9807 ± 2588 m and 1019 ± 552 m at high speeds (>249.6 m·m-1), with an overall average speed of 62.85 ± 14.7 m·m-1. This resulted in a mean HR of 74.2 ± 6% HR max and energy expenditure of 1259 ± 309 kcal. Significant and meaningful differences in movement kinematics were observed across position groups. CM covered the most distance resulting in the highest training load. FP covered the most distance at high speeds and mean HR values were highest in CM, CB, and FP positions.
#8 Predicting the Timing of the Peak of the Pubertal Growth Spurt in Elite Youth Soccer Players: Evaluation of Methods
Reference: Ann Hum Biol. 2020 Jun 16;1-23. doi: 10.1080/03014460.2020.1782989. Online ahead of print.
Authors: James Parr, Keith Winwood, Emma Hodson-Tole, Frederik J A Deconinck, Les Parry, James P Hill , Robert M Malina, Sean P Cumming
Summary: Three commonly used non-invasive protocols are implemented to estimate the timing at which PHV most likely occurs. Accurate estimation of circumpubertal years can aid in managing training load of adolescent athletes. Three protocols were compared against observed age at PHV: an estimate of 13.8 ± 1.0 years - generic age at PHV (from longitudinal measures); an estimate based on the maturity offset equation, predicted age at PHV ±1.0 year; a window of PHV based on 85 - 96% of predicted adult height at time of observation. A final sample of 23 (from 28) adolescent participants who were selected from the academy of an English Premier League club. Anthropometric measures were collected across five playing seasons; age at PHV was estimated with Super-Imposition by Translation and Rotation (SITAR). The three protocols were compared based on measures at 13.0 years. An age window based on predicted maturity offset did not improve estimation of PHV compared to generic age method; however, the percentage of predicted adult height window showed improvement in performance shown by the following results. Predicted age at PHV correctly assigned 15 participants (65%) as experiencing PHV, while the percentage height correctly assigned 17 participants (74%). Generic age and predicted age at PHV correctly predicted observed age at PHV for 14 participants (61%), percentage of adult height window correctly predicted 22 participants (96%).
#9 Psychosocial Outcomes Associated With Soccer Academy Involvement: Longitudinal Comparisons Against Aged Matched School Pupils
Reference: J Sports Sci. 2020 Jun 16;1-12. doi: 10.1080/02640414.2020.1778354. Online ahead of print.
Authors: Fieke Rongen, Jim McKenna, Stephen Cobley, Jason Cameron Tee, Kevin Till
Summary: Despite literature highlighting numerous risks to the healthy psychosocial development of youth elite academy soccer players, little of this research is based on high-quality research designs. This study employed a prospective longitudinal cohort design to track psychosocial outcomes of academy involvement within male youth elite soccer players (n = 33, U12-U16 age groups) compared to age-matched soccer-active school pupils (n = 44) over 12 months. Participants completed questionnaires assessing the most commonly raised psychosocial concerns at four equally spaced data collection periods (T1-T4). Repeated measures multivariate analysis of variance (MANOVAs) indicated that, over the year, both groups reported a healthy and improving stress and recovery balance, as well as positive and stable needs satisfaction and physical, psychological and social well-being. Academy players reported stable positive school-related quality of life, whereas school pupils reported increases from T3 to T4. Academy players reported consistent significantly higher total athletic identity and exclusivity of identity. Findings suggest that many concerns around negative psychosocial impacts of soccer academy involvement did not materialise in this context. However, heightened athletic identities remained a concern
#10 A Comparison of Bilateral vs. Unilateral-Biased Strength and Power Training Interventions on Measures of Physical Performance in Elite Youth Soccer Players
Reference: J Strength Cond Res. 2020 Jun 10. doi: 10.1519/JSC.0000000000003659. Online ahead of print.
Authors: Darren Stern, Oliver Gonzalo-Skok, Irineu Loturco, Anthony Turner, Chris Bishop
Summary: The aim of the present study was to compare the effects of bilateral and unilateral-biased strength and power training programs on measures of physical performance in male youth soccer players. Twenty-three elite youth players (age: 17.6 ± 1.2 years) were randomly assigned to either a unilateral (n = 11) or a bilateral (n = 12) group, who completed a strength and power intervention, twice per week for 6 weeks. The unilateral group completed rear foot elevated split squats (RFESS), single-leg countermovement jumps (SLCMJs), single-leg drop jumps (SLDJs), and single-leg broad jumps (SLBJs). The bilateral group intervention performed back squats, CMJs, drop jumps (DJ), and broad jumps (BJ). A 2 × 2 repeated measures analysis of variance showed no between-group differences. However, within-group differences were evident. The bilateral training group showed significant (p < 0.05) improvements in back squat strength (d = 1.27; %Δ = 26.01), RFESS strength (d = 1.64; %Δ = 23.34), BJ (d = 0.76; %Δ = 5.12), 10-m (d = -1.17; %Δ = 4.29), and 30-m (d = -0.88; %Δ = 2.10) performance. The unilateral group showed significant (p < 0.05) improvements in RFESS strength (d = 1.40; %Δ = 33.29), SLCMJ on the left leg (d = 0.76; %Δ = 9.84), SLBJ on the left leg (d = 0.97; %Δ = 6.50), 10 m (d = -1.50; %Δ = 5.20), and 505 on the right leg (d = -0.78; %Δ = 2.80). Standardized mean differences showed that bilateral training favored improvements in back squat strength and unilateral training favored improvements in RFESS strength, SLDJ on the right leg and 505 on the right leg. These results show that although both training interventions demonstrated trivial-to-large improvements in physical performance, the notion of training specificity was evident with unilateral training showing greater improvements in unilateral test measures.
The study profiled the match-day physical activities performed by substitutes focusing on the pre- and post-pitch-entry periods.
The effects of a Nordic hamstring exercise before vs. after football training was examined.
Following studies were retrieved for this week:
#1 Female Soccer Players' Psychological Profile: Differences Between Professional and Amateur Players
Reference: Int J Environ Res Public Health 2020 Jun 18;17(12):E4357. doi: 10.3390/ijerph17124357.
Authors: Cecilia Ruiz-Esteban , Aurelio Olmedilla, Inmaculada Méndez, Juan Jesús Tobal
Download link: https://www.mdpi.com/1660-4601/17/12/4357/pdf
Summary: The psychological variables that affect competitive performance are called the psychological profile of athletes. In recent years, the interest in female soccer players and the psychological characteristics that affect their performance has increased. The aim of the present study is to analyze the psychological characteristics of female professional soccer players and female amateur soccer players, as well as to determine the differences in the psychological profile of both groups. The participants were 134 federated female soccer players, with an average age of 18.28 years (SD = 4.05). To assess the psychological profile, the questionnaire on Psychological Characteristics related to Sports Performance (CPRD) by Gimeno, Buceta, and Pérez-Llantada (2001) was used. The results showed that female professional players presented higher values for motivation, while the female amateur players presented higher values for stress control and the influence of performance evaluation. These results can have a great impact on coaches' work, since they can help them to establish tasks and training methods consistent with the characteristics of their players.
#2 Directions of Single-Leg Landing Affect Multi-Segment Foot Kinematics and Dynamic Postural Stability in Male Collegiate Soccer Athletes
Reference: Gait Posture. 2020 Jun 13;80:285-291. doi: 10.1016/j.gaitpost.2020.06.007. Online ahead of print.
Authors: Shun Kunugi, Takashi Koumura, Ryota Myotsuzono, Akihiko Masunari, Naruto Yoshida, Shumpei Miyakawa, Naoki Mukai
Summary: Understanding lower limb kinematics and postural control in different directions of single-leg landings is critical to evaluate postural control and prevent lower limb injuries. However, foot and ankle kinematics and postural control during single-leg landings in different directions are less known. Therefore we questioned wheter the difference in the direction of single-leg landing affect the foot kinematics on the frontal plane and dynamic postural stability? A cross-sectional study was conducted. Forty-nine male collegiate soccer players performed single-leg forward (FL), 45° lateral (LL), and medial (ML) direction landings. The lower limb, foot (rearfoot, midfoot, forefoot), and ankle kinematics during an impact phase were evaluated, and a curve analysis was performed using a statistical parametric mapping method to compare the three landings. The three landings were compared in terms of postural control parameters, including time to stabilization (TTS), peak of ground reaction forces (GRFs), root-mean-square of the mediolateral GRFs for 0-0.4 s (GRFML0.4), loading rate, and magnitude of horizontal GRFs from 0-0.4 s (HGRF-0.4), 0.4-2.4 s (HGRF-2.4), and 3.0-5.0 s. Ankle and rearfoot kinematics in LL exhibited smaller eversion and pronation positions than FL and ML (p < 0.01). The TTS-mediolateral (TTS-ML) was longer in the LL than in FL and ML (p < 0.001). The GRFML0.4, HGRF-0.4, and -2.4 in the LL and ML were greater than those in the FL (p < 0.001). Directions of single-leg landing affect foot and ankle kinematics and postural stability. Specifically, the LL exhibits more inverted ankle and supinated rearfoot positions, and longer TTS-ML. Thus, the LL may induce stretching of the lateral ankle ligament. These findings can help understand foot kinematics and assess dynamic postural control.
#3 The Genetic Profile of Elite Youth Soccer Players and Its Association With Power and Speed Depends on Maturity Status
Reference: PLoS One. 2020 Jun 22;15(6):e0234458. doi: 10.1371/journal.pone.0234458. eCollection 2020.
Authors: Conall F Murtagh, Thomas E Brownlee, Edgardo Rienzi, Sebastian Roquero, Sacha Moreno, Gustavo Huertas, Giovani Lugioratto, Philipp Baumert, Daniel C Turner, Dongsun Lee, Peter Dickinson, K Amber Lyon, Bahare Sheikhsaraf, Betül Biyik, Andrew O'Boyle, Ryland Morgans, Andrew Massey, Barry Drust, Robert M Erskine
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7307776/pdf/pone.0234458.pdf
Summary: We investigated the association of multiple single nucleotide polymorphisms (SNPs) with athlete status and power/speed performance in elite male youth soccer players (ESP) and control participants (CON) at different stages of maturity. ESP (n = 535; aged 8-23 years) and CON (n = 151; aged 9-26 years) were genotyped for 10 SNPs and grouped according to years from predicted peak-height-velocity (PHV), i.e. pre- or post-PHV, to determine maturity status. Participants performed bilateral vertical countermovement jumps, bilateral horizontal-forward countermovement jumps, 20m sprints and modified 505-agility tests. Compared to CON, pre-PHV ESP demonstrated a higher ACTN3 (rs1815739) XX ('endurance') genotype frequency distribution, while post-PHV ESP revealed a higher frequency distribution of the PPARA (rs4253778) C-allele, AGT (rs699) GG genotype and NOS3 (rs2070744) T-allele ('power' genotypes/alleles). BDNF (rs6265) CC, COL5A1 (rs12722) CC and NOS3 TT homozygotes sprinted quicker than A-allele carriers, CT heterozygotes and CC homozygotes, respectively. COL2A1 (rs2070739) CC and AMPD1 (rs17602729) GG homozygotes sprinted faster than their respective minor allele carrier counterparts in CON and pre-PHV ESP, respectively. BDNF CC homozygotes jumped further than T-allele carriers, while ESP COL5A1 CC homozygotes jumped higher than TT homozygotes. To conclude, we have shown for the first time that pre- and post-PHV ESP have distinct genetic profiles, with pre-PHV ESP more suited for endurance, and post-PHV ESP for power and speed (the latter phenotypes being crucial attributes for post-PHV ESP). We have also demonstrated that power, acceleration and sprint performance were associated with five SNPs, both individually and in combination, possibly by influencing muscle size and neuromuscular activation.
#4 Talent Identification and Development in Soccer Since the Millennium
Reference: J Sports Sci. 2020 Jun 22;1-12. doi: 10.1080/02640414.2020.1766647. Online ahead of print.
Authors: A Mark Williams, Paul R Ford, Barry Drust
Summary: At the turn of the millennium, a review paper was published in this journal on talent identification and development in soccer (Williams & Reilly, 2000). In the current paper, we assess progress made in this field over the last twenty years relative to the areas for future research highlighted in the original review. We evaluate developments in light of the calls made by Williams and Reilly to: a) undertake more multidisciplinary rather than mono-disciplinary research; b) embrace longitudinal rather than cross-sectional research designs; c) expand the research base on female football; and, d) better identify the subjective criteria used by scouts when selecting one player over another for entry into a formalised training environment. The body of mono-disciplinary research on this topic continues to expand, and progress has been made in publishing multidisciplinary, prospective, longitudinal data sets, along with advanced statistical modelling procedures, as well as in identifying the experiential criteria used by scouts. We found some variables in these studies have predictive value from adolescence to adult performance level in soccer. We present suggestions for future research to enhance knowledge and understanding of the best practices underpinning the identification and development of future generations of professional players.
#5 Brief Cycles of Lower Limb Occlusion Accelerates Recovery Kinetics In Soccer Players
Reference: Phys Sportsmed. 2020 Jun 22. doi: 10.1080/00913847.2020.1785260. Online ahead of print.
Authors: Wael Daab, Mohamed Amine Bouzid, Mehdi Lajri, Mustapha Bouchiba, Haithem Rebai
Summary: The aim of this study was to assess the effect of intermittent vascular occlusion (IVO) on recovery following simulated soccer physical demand test in soccer players. Twelve soccer players completed the Loughborough Intermittent Shuttle Test (LIST) in two conditions placebo (PLA) and IVO followed by intermittent lower limb occlusion. Physical performance (Squat jump: SJ, countermovement jump: CMJ, maximal voluntary contraction: MVC, and 20 meters sprint: SP), muscle damage parameters (creatine kinase: CK, Lactate dehydrogenase: LDH), inflammatory parameter (C-reactive protein: CRP) and perceived muscle soreness (DOMS) were assessed before, immediately after (0h), and 24h, 48h and 72h following the exercise. Following the LIST, a decrease was observed in all Physical performance within 48h in PLA condition (p<0.05),compared to PLA treatment, IVO treatment attenuated the decrease of SJ and CMJ at 24h and at 48hand for MVC and SP within 48h after the LIST (p<0.05). CK and LDH levels increased within 24h post exercise in both conditions (p<0.05), but with a lower level in IVO compared to PLA condition (p<0.05). Likewise, DOMS values were significantly lower with IVO condition compared to PLA condition immediately and at 24hafter exercise. The results of the present study suggest that the application of IVO after simulated soccer physical demand test accelerated recovery kinetics in soccer players.
#6 Femur, Tibia, and Fibula Fractures Secondary to Youth Soccer: A Descriptive Study and Review of the Literature
Reference: Cureus. 2020 May 18;12(5):e8185. doi: 10.7759/cureus.8185.
Authors: Peter Zaki, Sayyar Khakimov, Joseph Hess, William Hennrikus
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7301417/pdf/cureus-0012-00000008185.pdf
Summary: Objectives Soccer is the most popular sport in the world and is one of the top sports with increased participation. Despite the vast and increasing numbers of soccer players, limited data are available on pediatric lower extremity injuries. In particular, the purpose of the study is to describe the epidemiology of femur, tibia, and fibula fractures secondary to youth soccer. Methods A retrospective review concerning soccer-related femur, tibia, and fibula fractures was conducted in children under the age of 18 years from January 1, 2000 to December 31, 2015 with statewide data from the Pennsylvania Trauma Systems Foundation (PTSF), Mechanicsburg, PA. Results A total of 258 youth soccer players were admitted for femur, tibia, and fibula fractures from 2000 to 2015. These fractures constituted 33% of soccer-related injuries in youth admitted at trauma centers. Sixty-five percent of the fractures involved the tibia and 34% involved the femur. Body contact injury resulted in 54% of the fractures and non-body contact injury resulted in 46% of the fractures. Athletes the age of 13 and older sustained 67% of the fractures and were more likely to incur contact injuries (p-value=0.000041) than those less than 13. Males sustained 67% of the fractures, and gender was not associated with the mechanism of injury (p-value=0.43). Open fractures included 10% of tibia fractures and did not occur in femur fractures. The growth plate was involved in 24% of the femur fractures and 17% of the tibia fractures. Conclusion Youth soccer has the potential for serious femur, tibia, and fibula fractures. Intervention programs should aim at reducing non-body contact mechanism in children < 13 years of age and body contact mechanism in children ≥ 13 years of age. Further research should investigate injury prevention methods such as potentially reducing body contact mechanism by improving the effectiveness of shin guards.
#7 Tuck jump score is not related to hopping performance or patient-reported outcome measures in female soccer players
Reference: Int J Sports Phys Ther. 2020 May;15(3):395-406.
Authors: Amelia J H Arundale, Joanna Kvist, Martin Hägglund, Anne Fältström
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7297000/pdf/ijspt-15-395.pdf
Summary: The tuck jump assessment was developed to identify players at risk for anterior cruciate ligament (ACL) injuries or gauge a player's progress through rehabilitation after ACL reconstruction. A tuck jump score of ≥ 6 out of 10 has been labeled poor and thought to identify players with high risk landing patterns. The purpose of this exploratory study was to examine if there was a relationship between tuck jump score, particularly tuck jump scores ≥ 6, hopping performance, and patient-reported outcome measures in female soccer players with ACL reconstruction (ACLR) and knee-healthy controls. Female soccer players (117 after ACLR, 117 knee-healthy) performed the single hop for distance, tuck jump assessment, and drop vertical jump (DVJ). All players were categorized based on as having a total tuck jump score ≥ 6 or < 6. Analyzing all players together, Spearman's rank correlations assessed if there were relationships between total tuck jump score or tuck jump scores ≥ 6 and single-legged hop limb symmetry or DVJ measures. Players with an ACLR also filled out the International Knee Documentation Committee 2000 Subjective Knee Form and the Knee injury Osteoarthritis Outcome Score. Spearman's rank correlations assessed if there were relationships between total tuck jump score or tuck jump scores ≥ 6 and patient-reported outcome measures. The mean tuck jump scores was 4.8 ± 1.8 (tuck jump score ≥ 6, 6.7 ± 0.9, tuck jump score < 6, 3.7 ± 1.1) with 87 (37%) athletes having tuck jump score ≥ 6. There were no significant relationships between tuck jump score or tuck jump score ≥ 6 and hopping performance or patient-reported outcome measures. The results of this current study indicate that tuck jump scores, including tuck jump scores ≥ 6, may not be related to functional or patient-reported outcome measures. Further work is needed to examine the clinical utility of the tuck jump assessment.
#8 Plantar Loading in the Youth Soccer Player During Common Soccer Movements and Risk for Foot Injury
Reference: Injury. 2020 Jun 12;S0020-1383(20)30515-5. doi: 10.1016/j.injury.2020.06.009. Online ahead of print.
Authors: Renato R Azevedo, Suellen B Nery, Darren J Stefanyshyn, Felipe P Carpes
Summary: Soccer players are at high risk of stress injuries in the foot. While most research addresses this issue in professional athletes, there is little information concerning young athletes. As soccer is practiced around the world since early infancy, we set out to determine whether young soccer athletes are susceptible to increased foot loading that increase risk factors for foot injuries in a similar manner as reported by the literature to the adult athlete. Twenty-six male adolescents (mean age 16 years old) were organized into two groups: soccer players (n = 13) and controls (n = 13). Groups were compared regarding foot sensitivity, ankle range of motion, Q-angle, and plantar pressure determined during running and cutting movements performed at maximal speed and using different shoes. Foot sensitivity, ankle range of motion and Q-angle did not differ between the groups. During performance of soccer actions, young players showed higher peak pressure in the lateral region of the foot including the fifth metatarsal region. These higher peaks were minimized by manipulation of the footwear. In summary, young soccer athletes show dynamic plantar pressure patterns that are related to foot injury in the adult athlete, and this condition can be minimized by the manipulation of the footwear. Additional attention should be paid to the young athlete in soccer aiming to minimize long-term risk for stress injuries in the foot.
#9 Increased Myocardial Mass and Attenuation of Myocardial Strain in Professional Male Soccer Players and Competitive Male Triathletes
Reference: Int J Cardiovasc Imaging. 2020 Jun 20. doi: 10.1007/s10554-020-01918-1. Online ahead of print.
Authors: Jitka Starekova, Tilo Thottakara, Gunnar K Lund, Götz H Welsch, Fabian J Brunner, Kai Muellerleile, Gerhard Adam, Marc Regier, Enver Tahir
Download link: https://link.springer.com/content/pdf/10.1007/s10554-020-01918-1.pdf
Summary: The purpose of this prospective study was to analyze the relationship between ventricular morphology and parameters of cardiac function in two different athletic groups and controls, using feature tracking cardiac magnetic resonance (FT-CMR). Twenty-three professional soccer players (22 ± 4 years), 19 competitive triathletes (28 ± 6 years) and 16 controls (26 ± 3 years) were included in the study. CMR was performed using a 1.5 T scanner. Cardiac chamber volumes, mass and biventricular global myocardial strain were obtained and compared. In comparison to the control subjects, athletes were characterized by a higher cardiac volume (p < 0.0001), higher cardiac mass (p < 0.001), reduced longitudinal strain of the left and right ventricle (p < 0.05 and p < 0.01 respectively) and reduced left ventricular radial strain (p < 0.05). Soccer players revealed higher amounts of left ventricular mass (87 ± 15 vs. 75 ± 13 g/m2, p < 0.05) than triathletes. Moreover, they showed a greater decrease in left and right ventricular longitudinal strain (p < 0.05 and p < 0.05) as well as in radial left ventricular strain (p < 0.05) in comparison to triathletes. An increase in left ventricular mass correlated significantly with a decrease in longitudinal (r = 0.47, p < 0.001) and radial (r = - 0.28, p < 0.05) strain. In athletes, attenuation of strain values is associated with cardiac hypertrophy and differ between soccer players and triathletes. Further studies are needed to investigate whether it is an adaptive or maladaptive change of the heart induced by intense athletic training.
#10 Systematic Video Analysis of ACL Injuries in Professional Male Football (Soccer): Injury Mechanisms, Situational Patterns and Biomechanics Study on 134 Consecutive Cases
Reference: Br J Sports Med. 2020 Jun 19;bjsports-2019-101247. doi: 10.1136/bjsports-2019-101247. Online ahead of print.
Authors: Francesco Della Villa, Matthew Buckthorpe, Alberto Grassi, Alberto Nabiuzzi, Filippo Tosarelli, Stefano Zaffagnini, Stefano Della Villa
Download link: https://bjsm.bmj.com/content/bjsports/early/2020/06/19/bjsports-2019-101247.full.pdf
Summary: A few small studies have reported on the mechanisms of ACL injury in professional male football. The purpose was to describe the mechanisms, situational patterns and biomechanics (kinematics) of ACL injuries in professional male football matches. We identified 148 consecutive ACL injuries across 10 seasons of professional Italian football. 134 (90%) injury videos were analysed for mechanism and situational pattern, while biomechanical analysis was possible in 107 cases. Three independent reviewers evaluated each video. ACL injury epidemiology (month), timing within the match and pitch location at the time of injury were also reported. 59 (44%) injuries were non-contact, 59 (44%) were indirect contact and 16 (12%) were direct contact. Players were frequently perturbed immediately prior to injury. We identified four main situational patterns for players who suffered a non-contact or an indirect contact injury: (1) pressing and tackling (n=55); (2) tackled (n=24); (3) regaining balance after kicking (n=19); and (4) landing from a jump (n=8). Knee valgus loading (n=83, 81%) was the dominant injury pattern across all four of these situational patterns (86%, 86%, 67% and 50%, respectively). 62% of the injuries occurred in the first half of the matches (p<0.01). Injuries peaked at the beginning of the season (September-October) and were also higher at the end of the season (March-May). 88% of ACL injuries occurred without direct knee contact, but indirect contact injuries were as frequent as non-contact injuries, underlying the importance of mechanical perturbation. The most common situational patterns were pressing, being tackled and kicking.
The purpose was to analyze the day-to-day variance of a typical weekly external training workload of two professional soccer teams from Portugal and Netherlands