Blog archive

Thu

14

Dec

2017

Football is...(#49)

Eccentric strength to improve functional H:Q ratio

Wed

13

Dec

2017

Latest research in football - week 49 - 2017

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 Injury and illness epidemiology in soccer - effects of global geographical differences - a call for standardized and consistent research studies
Reference: Biol Sport. 2017 Sep;34(3):249-254. doi: 10.5114/biolsport.2017.66002. Epub 2017 Feb 19.
Authors: Eirale C, Gillogly S, Singh G, Chamari K
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5676321/pdf/JBS-34-66002.pdf
Summary: Soccer is the most popular sport in the world. While injuries and illnesses can affect the players' health and performance, they can also have a major economic impact on teams. Moreover, several studies have shown the favourable association between higher player availability and team success. Therefore, injury prevention could directly impact clubs' financial balance and teams' performance via increased player availability. To be able to develop effective methods of injury prevention, it is vital to first determine the scope and the degree of the problem: the mechanisms and types of injuries, their frequency and severity, etc. According to the most widely known prevention model, systematic injury surveillance is the first and most fundamental step towards injury prevention. Since epidemiological studies have shown that injuries and illnesses in soccer players differ from region to region, it is important to establish a specific injuries and illness database in order to guide specific preventive actions. Since Asia is the largest continent, with the highest number of soccer players, and in the light of the long-term research on injuries performed in UEFA clubs, the authors of the present article present the AFC surveillance. Some methodological issues related to this prospective design study are discussed. The definition of injury and illness and the methods to track players' exposure are described along with the potential challenges related to such a vast scale study. This article is also a call for action to have consistent and standardized epidemiological studies on soccer injuries and illnesses, with the aim to improve their prevention.


#2 Blood pressure, heart rate and perceived enjoyment after small-sided soccer games and repeated sprint in untrained healthy adolescents
Reference: Biol Sport. 2017 Sep;34(3):219-225. doi: 10.5114/biolsport.2017.65997. Epub 2017 Feb 19.
Authors: Hammami A, Kasmi S, Farinatti P, Fgiri T, Chamari K, Bouhlel E
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5676316/pdf/JBS-34-65997.pdf
Summary: The purpose of this study was to examine systolic (SBP) and diastolic blood pressure (DBP), heart rate (HR), rating of perceived exertion (RPE) and perceived enjoyment responses to a repeated-sprint training session (RST) compared to a small-sided soccer game session (SSG) in untrained adolescents. Twelve healthy post-pubertal adolescent males (age 15.8±0.6 years, body mass 59.1±3.7 kg, height 1.7±0.1m) performed RST and SSG sessions in a randomized and counterbalanced order. Blood pressure and HR were measured at rest and at 10, 20 and 30 minutes after interventions, and RPE and enjoyment were assessed. RST and SSG elicited similar exercise HR (74.0% vs. 73.7% of HR peak during RST and SSG respectively, P>0.05). There was no significant change in SBP or DBP after the 2 interventions (all P>0.05, ES<0.5) with a trend to a decrease in SBP after SSG at 30 min after intervention (moderate effect, ES=0.6). Pearson's correlation analysis revealed a significant and large correlation between baseline BP values and magnitude of decline after both RST and SSG. Heart rate during recovery was higher compared with baseline at all times after both sessions (all P<0.05), with HR values significantly lower after SSG versus RST at 30 min after interventions (82.3±3.2 versus 92.4±3.2 beats/min, respectively, P=0.04). RPE was significantly lower (P=0.02, ES=1.1) after SSG than after RST, without significant differences in enjoyment. In conclusion, repeated sprint and small-sided games elicited similar exercise intensity without a significant difference in perceived enjoyment. Post-exercise hypotension after the two forms of training may depend on resting BP of subjects.


#3 Immediate Effects of Ankle Balance Taping with Kinesiology Tape for Amateur Soccer Players with Lateral Ankle Sprain: A Randomized Cross-Over Design
Reference: Med Sci Monit. 2017 Nov 21;23:5534-5541.
Authors: Kim MK, Shin YJ
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5706382/pdf/medscimonit-23-5534.pdf
Summary: The objective of this study was to investigate the immediate effect on gait function when ankle balance taping is applied to amateur soccer players with lateral ankle sprain. A cross-over randomized design was used. Twenty-two soccer players with an ankle sprain underwent 3 interventions in a random order. Subjects were randomly assigned to ankle balance taping, placebo taping, and no taping groups. The assessment was performed using the GAITRite portable walkway system, which records the location and timing of each footfall during ambulation. Significant differences were found in the velocity, step length, stride length, and H-H base support among the 3 different taping methods (p<0.05). The ankle balance taping group showed significantly greater velocity, step length, and stride length in comparison to the placebo and no taping group. The ankle balance taping group showed a statistically significant decrease (p<0.05) in the H-H base support compared to the placebo and no taping groups, and the placebo group showed significantly greater velocity in comparison to the no taping group (p<0.05). We conclude that ankle balance taping that uses kinesiology tape instantly increased the walking ability of amateur soccer players with lateral ankle sprain. Therefore, ankle balance taping is a useful alternative to prevent and treat ankle sprain of soccer players.


#4 Does Maturity Status Affect The Relationship Between Anaerobic Speed Reserve And Multiple Sprints Sets Performance in Young Soccer Players?
Reference: J Strength Cond Res. 2017 Nov 29. doi: 10.1519/JSC.0000000000002266. [Epub ahead of print]
Authors: Selmi MA, Al-Haddabi B, Yahmed MH, Sassi RH
Summary: The purpose of this study is to examine the relationship between repeated-sprint sets (RSS) performance indices and anaerobic speed reserve (ASR) in young soccer players of different maturity status. One hundred and seventy nine young male soccer players (11.1 to 17.8 years) classified as pre- (n=50), circum- (n=60), or post- (n=69) peak height velocity (PHV) performed multi-stage shuttle run test (MRST) to measure maximal aerobic speed (MAS), 30-m sprint with 10-m splits to estimate maximal anaerobic speed (MAnS), and RSS test. ASR was calculated as the difference between MAS and MAnS. The RSS indices, MAS, MAnS and ASR were significantly different in the three maturity groups (p< 0.001; ES =0.12-0.64). Correlations between RSS performance indices and ASR varied considerably depending on maturity status. Very large correlations between ASR and RSS indices expressed as sum sprint time (SST) and best sprint time (BST) were found for pre- and circum-PHV groups (r=-0.76, -0.79 and r=-0.82, -0.86, respectively). In the post-PHV group, ASR was moderately associated with both SST (r=-0.45) and BST (r=-0.46). To sum up, these results highlighted that the ASR is more related to factors of RSS performance in pre- and circum-PHV male soccer players compared with post-PHV ones. These findings could help coaches and strength and conditioning professionals to better understand how the relationship between ASR and RSS evolve across the maturity and may be considered, therefore, useful in youth soccer selection/training process.


#5 Aerobic Fitness in Top-Class Soccer Referees
Reference: J Strength Cond Res. 2017 Nov 16. doi: 10.1519/JSC.0000000000002264. [Epub ahead of print]
Authors: Castagna C, Bizzini M, Araujo Povoas SC, Schenk K, Busser G, DʼOttavio S
Summary: The aim of this study was to examine the aerobic fitness status of top-class male soccer officials using a cross-sectional design and known population group constructs. Fifty-two field referees (FRs, age 38.4 ± 3.3 years; height 181 ± 5.6 cm; body mass 76.8 ± 6.8 kg; body mass index [BMI] 23.4 ± 1.7 kg·m; body fat 20.4 ± 3.6%; and international refereeing experience 5 ± 3.5 years) and 104 assistant referees (ARs, age 37.8 ± 4.1 years; height 176.9 ± 7.5 cm; body mass 72.1 ± 7.4 kg; BMI 23 ± 1.6 kg·m; body fat 19.2 ± 3.6%; and international refereeing experience 7 ± 3.8 years) from 53 National Football Associations worldwide, and candidates of the preliminary open-list developed by the FIFA Refereeing Department for the 2014 World Cup Final Tournament, were tested for aerobic fitness in laboratory conditions with a progressive speed treadmill test to exhaustion. Large (+8.54%, d = 0.8) and small (+3.1%, d = 0.3) differences in absolute (L·min) and relative (ml·kg·min) V[Combining Dot Above]O2max were found between FR and AR, respectively. Trivial differences (d = 0.07) were shown in running economy (RE) (6 minutes at 8 km·h) between AR and FR. Using the scaling notation (b = 0.64), medium and significant differences were found between match officials for V[Combining Dot Above]O2max and RE (FR > AR; d = 0.6 and 0.67, respectively). Using receiver operating characteristic curve statistics, cutoff values of 3.93 L·min and 50.6 ml·kg·min were detected in absolute and relative V[Combining Dot Above]O2max for the FR and the AR (FR > AR), respectively. The FR showed superior aerobic fitness compared with AR. Training prescription should consider intensities at anaerobic threshold speed (14 km·h, 91% heart rate max) when aerobic fitness development is the aim in elite officials.


#6 Skill not athleticism predicts individual variation in match performance of soccer players
Reference: Proc Biol Sci. 2017 Dec 13;284(1868). pii: 20170953. doi: 10.1098/rspb.2017.0953.
Authors: Wilson RS, David GK, Murphy SC, Angilletta MJ Jr, Niehaus AC, Hunter AH, Smith MD
Summary: Just as evolutionary biologists endeavour to link phenotypes to fitness, sport scientists try to identify traits that determine athlete success. Both disciplines would benefit from collaboration, and to illustrate this, we used an analytical approach common to evolutionary biology to isolate the phenotypes that promote success in soccer, a complex activity of humans played in nearly every modern society. Using path analysis, we quantified the relationships among morphology, balance, skill, athleticism and performance of soccer players. We focused on performance in two complex motor activities: a simple game of soccer tennis (1 on 1), and a standard soccer match (11 on 11). In both contests, players with greater skill and balance were more likely to perform better. However, maximal athletic ability was not associated with success in a game. A social network analysis revealed that skill also predicted movement. The relationships between phenotypes and success during individual and team sports have potential implications for how selection acts on these phenotypes, in humans and other species, and thus should ultimately interest evolutionary biologists. Hence, we propose a field of evolutionary sports science that lies at the nexus of evolutionary biology and sports science. This would allow biologists to take advantage of the staggering quantity of data on performance in sporting events to answer evolutionary questions that are more difficult to answer for other species. In return, sports scientists could benefit from the theoretical framework developed to study natural selection in non-human species.


#7 Effects of lower extremity injuries on aerobic exercise capacity, anaerobic power, and knee isokinetic muscular function in high school soccer players
Reference: J Phys Ther Sci. 2017 Oct;29(10):1715-1719. doi: 10.1589/jpts.29.1715. Epub 2017 Oct 21.
Authors: Ko KJ, Ha GC, Kim DW, Kang SJ
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5683996/pdf/jpts-29-1715.pdf
Summary: The study investigated the effects of lower extremity injuries on aerobic exercise capacity, anaerobic power, and knee isokinetic muscular function in high school soccer players. The study assessed U High School soccer players (n=40) in S area, South Korea, divided into 2 groups: a lower extremity injury group (n=16) comprising those with knee and ankle injuries and a control group (n=24) without injury. Aerobic exercise capacity, anaerobic power, and knee isokinetic muscular function were compared and analyzed. Regarding the aerobic exercise capacity test, significant differences were observed in maximal oxygen uptake and anaerobic threshold between both groups. For the anaerobic power test, no significant difference was observed in peak power and average power between the groups; however, a significant difference in fatigue index was noted. Regarding the knee isokinetic muscular test, no significant difference was noted in knee flexion, extension, and flexion/extension ratio between both groups. Lower extremity injury was associated with reduced aerobic exercise capacity and a higher fatigue index with respect to anaerobic exercise capacity. Therefore, it seems necessary to establish post-injury training programs that improve aerobic and anaerobic exercise capacity for soccer players who experience lower extremity injury.


#8 Seasonal Training Load and Wellness Monitoring in a Professional Soccer Goalkeeper
Reference: Int J Sports Physiol Perform. 2017 Nov 28:1-13. doi: 10.1123/ijspp.2017-0472. [Epub ahead of print]
Authors: Malone JJ, Jaspers A, Helsen WF, Merks B, Frencken WG, Brink MS
Summary: The purpose of this investigation was to: (a) quantify the training load practices of a professional soccer GK, and (b) investigate the relationship between the training load observed and the subsequent self-reported wellness response. One male goalkeeper playing for a team in the top league of the Netherlands participated in this case study. Training load data were collected across a full season using a global positioning system (GPS) device and session rating of perceived exertion (session-RPE). Data was assessed in relation to the number of days to a match (MD- and MD+). In addition, self-reported wellness was assessed using a questionnaire. Duration, total distance, average speed, PlayerLoadTM and load (derived from session-RPE) were highest on MD. The lowest values for duration, total distance and PlayerLoadTM were observed on MD-1 and MD+1. Total wellness scores were highest on MD and MD-3 and were lowest on MD+1 and MD-4. Small to moderate correlations between training load measures (duration, total distance covered, high deceleration efforts and load) and the self-reported wellness scores were found. This exploratory case-study provides novel data about the physical load undertaken by a goalkeeper during one competitive season. The data suggest there are small to moderate relationships between training load indicators and self-reported wellness. This weak relation indicates that the association is not meaningful. This may be due to the lack of position-specific training load parameters we can currently measure in the applied context.


#9 Irisin levels correlate with bone mineral density in soccer players
Reference: J Biol Regul Homeost Agents. 2017 Oct-Dec,;31(4 suppl 1):21-28.
Authors: Colaianni G, Notarnicola A, Sanesi L, Brunetti G, Lippo L, Celi M, Moretti L, Pesce V, Vicenti G, Moretti B, Colucci S, Grano M
Summary: Irisin, a novel myokine produced in response to physical exercise by skeletal muscle, displays anabolic effect on bone and can improve the bone-loss-induced osteoporosis in hind limb suspended mice. It is well known that muscles positively impact the skeleton and in different sports, including soccer, total body bone mineral density (TB-BMD) is elevated. Therefore, we have investigated the correlation between irisin serum levels and total and bone sub-regional BMD in soccer players never studied before. In this study, Caucasian football players of Bari team have been enrolled. Their sera were collected to measure by ELISA kit irisin levels and by dual-energy X-ray absorptiometry (DEXA) analysis measurements of BMD (g • cm−2) in the whole body and different bone sub-regions (head, arms, legs, ribs, dorsal vertebrae, lumbar vertebrae, pelvis) were performed. The BMC (g) was measured in the whole body. By means of Pearson’s (R) and Cohen’s (d) coefficient we investigated the linear association between the irisin serum levels and BMD. In soccer players, we have found a positive correlation between irisin and TB-BMD as demonstrated by the values of Pearson and Cohen’s (d) coefficient. Furthermore, linear association was detected between irisin and BMD of different bone-site such as right arm, lumbar vertebrae and head. A positive trend was also observed analyzing circulating levels of irisin and bone mineral content as well as total Z-score. In conclusion, we have demonstrated the correlation between irisin and total or bone sub-regional BMD in soccer players for the first time, an additional systemic effect of the “sport-hormone” defined myokine.


#10 Prognostic factors for specific lower extremity and spinal musculoskeletal injuries identified through medical screening and training load monitoring in professional football (soccer): a systematic review
Reference: BMJ Open Sport Exerc Med. 2017 Sep 21;3(1):e000263. doi: 10.1136/bmjsem-2017-000263. eCollection 2017.
Authors: Hughes T, Sergeant JC, Parkes MJ, Callaghan MJ
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5623323/pdf/bmjsem-2017-000263.pdf
Summary: Medical screening and load monitoring procedures are commonly used in professional football to assess factors perceived to be associated with injury. The aim was to identify prognostic factors (PFs) and models for lower extremity and spinal musculoskeletal injuries in professional/elite football players from medical screening and training load monitoring processes. The MEDLINE, AMED, EMBASE, CINAHL Plus, SPORTDiscus and PubMed electronic bibliographic databases were searched (from inception to January 2017). Prospective and retrospective cohort studies of lower extremity and spinal musculoskeletal injury incidence in professional/elite football players aged between 16 and 40 years were included. The Quality in Prognostic Studies appraisal tool and the modified Grading of Recommendations Assessment, Development and Evaluation synthesis approach was used to assess the quality of the evidence. Fourteen studies were included. 16 specific lower extremity injury outcomes were identified. No spinal injury outcomes were identified. Meta-analysis was not possible due to heterogeneity and study quality. All evidence related to PFs and specific lower extremity injury outcomes was of very low to low quality. On the few occasions where multiple studies could be used to compare PFs and outcomes, only two factors demonstrated consensus. A history of previous hamstring injuries (HSI) and increasing age may be prognostic for future HSI in male players. The assumed ability of medical screening tests to predict specific musculoskeletal injuries is not supported by the current evidence. Screening procedures should currently be considered as benchmarks of function or performance only. The prognostic value of load monitoring modalities is unknown.


#11 Effects of Plyometric and Directional Training on Speed and Jump Performance in Elite Youth Soccer Players
Reference: J Strength Cond Res. 2017 Nov 22. doi: 10.1519/JSC.0000000000002371. [Epub ahead of print]
Authors: Beato M, Bianchi M, Coratella G, Merlini M, Drust B
Summary: Soccer players perform approximately 1350 activities (every 4-6 s), such as accelerations/decelerations, and changes of direction (COD) during matches. It is well established that COD and plyometric training have a positive impact on fitness parameters in football players. This study analyzed the effect of a complex COD and plyometric protocol (CODJ-G) compared to an isolated COD protocol (COD-G) training on elite football players.A randomized pre-post parallel group trial was used in this study. Twenty-one youth players were enrolled in this study (mean ± SDs; age 17 ± 0.8 years, weight 70.1 ± 6.4 kg, height 177.4 ± 6.2 cm). Players were randomized into two different groups: CODJ-G (n = 11) and COD-G (n = 10), training frequency of 2 times a week over 6 weeks. Sprint 10, 30 and 40 m, long jump, triple hop jump, as well as 505 COD test were considered. Exercise-induced within-group changes in performance for both CODJ-G and COD-G: long jump (effect size (ES) = 0.32 and ES = 0.26, respectively), sprint 10 m (ES = -0.51 and ES = -0.22 respectively), after 6 weeks of training. Moreover, CODJ-G reported substantially better results (between-group changes) in long jump test (ES = 0.32). In conclusion, this study showed that short-term protocols (CODJ-G and COD-G) are important and able to give meaningful improvements on power and speed parameters in a specific soccer population. CODJ-G showed a larger effect in sprint and jump parameters compared to COD-G after the training protocol. This study offers important implications for designing COD and jumps training in elite soccer.

Tue

12

Dec

2017

Football is...(#48)

Upper-body stability to withstand opposition players' challenges

Mon

11

Dec

2017

Latest research in football - week 48 - 2017

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 Movement pattern and physiological response in recreational small-sided football - effect of number of players with a fixed pitch size
Reference: J Sports Sci. 2017 Nov 13:1-8. doi: 10.1080/02640414.2017.1402552. [Epub ahead of print]
Authors: Randers MB, Orntoft C, Hagman M, Nielsen JJ, Krustrup P
Summary: Recreational soccer is an effective health-promoting activity, but it is unclear how different game formats influence internal and external load. Thus, to be able to advise how to maximise the outcome of recreational football, we examined movement pattern and physiological response in 11 untrained men (32.6 ± 6.7 yrs, 23.3 ± 4.9 fat%, 43.4 ± 5.3 ml·min-1·kg-1) during three football sessions comprising 4 × 12 min of 3v3, 5v5 or 7v7 with a constant pitch size of 20 × 40 m. Movement pattern, heart rate (HR), blood lactate and RPE were measured during and after the 12-min periods. Greater (P < 0.05) total distance and high-speed distance was covered during 3v3 than 5v5 (14 and 30%) and 7v7 (15 and 75%). Mean HR was higher in 3v3 (85.7 ± 5.7%HRmax) and 5v5 (84.2 ± 5.1%HRmax) than in 7v7 (80.7 ± 4.6%HRmax, P < 0.05) and percentage time >90%HR was higher in 3v3 (43 ± 18%, P < 0.05) than in 5v5 (28 ± 21%) and 7v7 (18 ± 14%). Blood lactate was higher in 3v3 (7.4 ± 2.7 mmol·l-1) than in 7v7 (4.5 ± 2.2 mmol·l-1, P < 0.001) but not in 5v5 (6.1 ± 2.1 mmol·l-1, P = 0.061). RPE was higher in 3v3 (6.7 ± 2.3, P < 0.01) than in 5v5 (5.2 ± 2.2) and 7v7 (4.3 ± 2.3). In conclusion, higher external and internal load was found with fewer players, when the pitch size is fixed.


#2 Body fat percentage comparisons between four methods in young football players: are they comparable?
Reference: Nutr Hosp. 2017 Oct 24;34(5):1119-1124. doi: 10.20960/nh.760.
Authors: Lozano Berges G, Matute Llorente A, Gomez Bruton A, Gonzalez Aguero A, Vicente Rodriguez G, Casajus JA
Download link: revista.nutricionhospitalaria.net/index.php/nh/article/download/760/664
Summary: Dual X-ray absorptiometry (DXA), air displacement plethysmography (ADP), bioelectrical impedance analysis (BIA) and anthropometry are four body composition methods that have been frequently used for the assessment of body fat percentage (%BF) in athletes. However, the agreement between these methods has not been studied yet in adolescent football players. The aim of this study was to compare %BF calculated by DXA, ADP, BIA and anthropometry in 92 participants. Sixty-four males (13.4 ± 0.6 years of age) and 28 females (13.4 ± 0.6 years) participated in this study. %BF was measured with four methods: DXA, ADP, BIA, and anthropometry. ADP %BF was calculated by using Siri's equation. The equation proposed by Slaughter et al. was used to calculate %BF by anthropometry. Paired t-test was used to compare %BF means. The heteroscedasticity was calculated by Bland-Altman analyses. Both in males and females, DXA, ADP, BIA and Slaughter et al. equation demonstrated significant %BF differences when compared to each other (p < 0.05); 95% limits of agreements ranged from 5.13 to 15.09% points. Only BIA showed heteroscedasticity compared to the other methods in both genders (p < 0.05). Although DXA, ADP, BIA, and anthropometry have been used in the scientific literature in order to assess %BF in adolescent football players, these results demonstrate that these body composition methods are not interchangeable in this population.


#3 Adoption and use of an injury prevention exercise programme in female football: a qualitative study among coaches
Reference: Scand J Med Sci Sports. 2017 Nov 11. doi: 10.1111/sms.13012. [Epub ahead of print]
Authors: Lindblom H, Carlfjord S, Hagglund M
Summary: This study focuses on an injury prevention exercise programme (IPEP), Knee Control, which has been shown to reduce the incidence of acute knee injury in female adolescent football players. The aim was to explore the factors influencing coaches' adoption and use of Knee Control within female football in Sweden. This was a qualitative study involving interviews with 20 strategically selected coaches for female football teams, predominantly adolescent teams. The semi-structured interview guide was influenced by the Health Belief Model, and an ecological perspective was adopted during the interviews. Interviews were analysed with qualitative content analysis. The results illustrate the different influences that interact on adoption and use of Knee Control by coaches. The coaches described themselves as crucial for Knee Control adoption and use, but external facilitators and barriers such as resources for training, social support from other coaches, clubs and football associations and player buy-in were also described as important. Knee Control characteristics, such as how well the programme fit the team, also influenced use of Knee Control. Many coaches modified the programme to improve player buy-in and Knee Control fit. Such modifications may risk compromising the preventive effect but may increase feasibility, i.e. the ease of using Knee Control, and thereby long-term use. These findings may guide the design and delivery of future IPEPs, and improve use of Knee Control, for example by expanding the programme to fit different target groups and supporting coaches and players in the use of Knee Control.


#4 Measurement properties and feasibility of the Loughborough soccer passing test: A systematic review
Reference: J Sports Sci. 2017 Nov 24:1-13. doi: 10.1080/02640414.2017.1409611. [Epub ahead of print]
Authors: Wen D, Robertson S, Hu G, Song B, Chen H
Summary: The purpose of this paper was to systematically review the literature and examine the research methodological quality, measurement properties and feasibility of the Loughborough Soccer Passing Test (LSPT). Databases were searched up to June 2017. Twenty five studies fulfilled the eligibility criteria. The main methodological limitations of the studies were the small sample size and the lack of information on participants and eligibility criteria. Results showed that test-retest reliability of the LSPT was moderate to excellent. Good discriminative validity was found between playing levels and ages. The LSPT was positively correlated with sprint, dribbling, and agility test; however, a weak correlation was established with in-game performance. Test responsiveness (an ability to detect change over time) to some external interventions was observed in studies. Adjusted Cronbach's alpha (α = 0.67), smallest worthwhile change (SWC = 0.8-3.8) and minimal detectable change (MDC50 = 1.9-11.3) were calculated based on available data. The findings indicate that the LSPT has acceptable test-retest reliability and discriminative validity. However, it may not be a feasible and effective way to interpret the intra-individual change of skill performance in practice. Future work should be undertaken to establish additional measurement properties of the LSPT, and to improve its practical feasibility.


#5 Neural bases of ingroup altruistic motivation in soccer fans
Reference: Sci Rep. 2017 Nov 23;7(1):16122. doi: 10.1038/s41598-017-15385-7.
Authors: Bortolini T, Bado P, Hoefle S, Engel A, Zahn R, de Oliveira Souza R, Dreher JC, Moll J
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5700961/pdf/41598_2017_Article_15385.pdf
Summary: Humans have a strong need to belong to social groups and a natural inclination to benefit ingroup members. Although the psychological mechanisms behind human prosociality have extensively been studied, the specific neural systems bridging group belongingness and altruistic motivation remain to be identified. Here, we used soccer fandom as an ecological framing of group membership to investigate the neural mechanisms underlying ingroup altruistic behaviour in male fans using event-related functional magnetic resonance. We designed an effort measure based on handgrip strength to assess the motivation to earn money (i) for oneself, (ii) for anonymous ingroup fans, or (iii) for a neutral group of anonymous non-fans. While overlapping valuation signals in the medial orbitofrontal cortex (mOFC) were observed for the three conditions, the subgenual cingulate cortex (SCC) exhibited increased functional connectivity with the mOFC as well as stronger hemodynamic responses for ingroup versus outgroup decisions. These findings indicate a key role for the SCC, a region previously implicated in altruistic decisions and group affiliation, in dovetailing altruistic motivations with neural valuation systems in real-life ingroup behaviour.


#6 Novel mathematical model to estimate ball impact force in soccer
Reference: Sports Biomech. 2017 Nov 22:1-17. doi: 10.1080/14763141.2017.1364415. [Epub ahead of print]
Authors: Iga T, Nunome H, Sano S, Sato N, Ikegami Y
Summary: The purpose was to assess ball impact force during soccer kicking is important to quantify from both performance and chronic injury prevention perspectives. We aimed to verify the appropriateness of previous models used to estimate ball impact force and to propose an improved model to better capture the time history of ball impact force. A soccer ball was fired directly onto a force platform (10 kHz) at five realistic kicking ball velocities and ball behaviour was captured by a high-speed camera (5,000 Hz). The time history of ball impact force was estimated using three existing models and two new models. A new mathematical model that took into account a rapid change in ball surface area and heterogeneous ball deformation showed a distinctive advantage to estimate the peak forces and its occurrence times and to reproduce time history of ball impact forces more precisely, thereby reinforcing the possible mechanics of 'footballer's ankle'. Ball impact time was also systematically shortened when ball velocity increases in contrast to practical understanding for producing faster ball velocity, however, the aspect of ball contact time must be considered carefully from practical point of view.


#7 Somatotrope Pituitary Function in Professional Soccer Players
Reference: Exp Clin Endocrinol Diabetes. 2017 Nov 17. doi: 10.1055/s-0043-119876. [Epub ahead of print]
Authors: Roser P, Wehrhahn T, Krogmann H, Riedel N, Marshall RP, Gille J, Flitsch J, Aberle J
Summary: Soccer is associated with repetitive head trauma, which, as it is known from sports like football and boxing, can result in hypopituitarism. Gonadotropins and GH are the most common pituitary hormones to become deficient. GH deficiency is associated with an increased risk of cardiovascular mortality and has negative influence on body mass index, visceral fat mass, insulin resistance and sensitivity, bone mineral density and inflammatory markers. Therefore the aim of this study was to evaluate the somatotrope pituitary function in professional soccer players. This clinical study included 15 male, professional soccer players with at least 10 years of professional training. Basal hormonal parameters of the pituitary axis were obtained from the participants. To assess GH-IGF-I axis, glucagon stimulation tests were used. Rise in growth hormone during glucagon test was analyzed and the prevalence of newly diagnosed hormone deficiencies was evaluated. Mean age of all participants was 31±10 years. None of the 15 soccer players had GH deficiency. Mean rising factor of GH after stimulation with glucagon was 100 in all participants. We did not find signs of ACTH, TSH or LH/FSH deficiency in any player. In this small collective of soccer players we did not find playing soccer to be a risk factor for the development of GH-deficiency. According to our data screening for somatotrope deficiency is not necessary. Further investigations in larger cohorts are needed.


#8 Correction to: Tanner-Whitehouse Skeletal Ages in Male Youth Soccer Players: TW2 or TW3?
Reference: Sports Med. 2017 Nov 21. doi: 10.1007/s40279-017-0827-7. [Epub ahead of print]
Authors: Malina RM, Coelho-E-Silva MJ, Figueiredo AJ, Philippaerts RM, Hirose N, Reyes MEP, Gilli G, Benso A, Vaeyens R, Deprez D, Guglielmo LGA, Buranarugsa R
Download link: https://link.springer.com/content/pdf/10.1007%2Fs40279-017-0827-7.pdf
Summary: An Online First version of this article was made available online at https://link.springer.com/article/10.1007%2Fs40279-017-0799-7 on 29 October 2017. Errors were subsequently identified in the article, and the following corrections should be noted.


#9 The functional movement screen (FMSTM) in elite young soccer players between 14 and 20 years: Composite score, individual test scores and asymmetries
Reference: Int J Sports Phys Ther. 2017 Nov;12(6):977-985.
Authors: Marques VB, Medeiros TM, de Souza Stigger F, Nakamura FY, Baroni BM
Summary: The Functional Movement Screen (FMS™) is a widely used seven-test battery used by practitioners working in sport medicine. The FMS™ composite score (sum of seven tests) in soccer athletes from different competitive levels has been well explored in literature, but the specific movement deficits presented by young high competitive level players remains unclear. The aim of the present study was to provide a detailed description of the performance of elite young soccer players (age 14-20 years) on the FMS™ testing battery. One-hundred and three young soccer players (14-20 years) from a premier league club were assessed by two experienced raters using the FMS™ testing battery. FMS™ composite score, individual-test scores and asymmetries were considered for analysis, and comparisons between age categories were performed. FMS™ composite scores ranged from 9 to 16 points (median=13 points). 82% of the athletes had a composite score ≤14 points, and 91% were classified into the "Fail" group (score 0 or 1 in at least one test). Almost half of athletes (48%) had poor performance (i.e., individual score < 2) in "deep squat" test. Most of athletes in the younger categories (under-15 and under-16) had poor performance in the "trunk stability push-up" test (70%) and in the "rotary stability" test (74%). Asymmetry in at least one of five unilateral FMS™ tests was found in 65% of athletes. High-performance young soccer players have important functional deficits, especially in tasks involving deep squat and trunk stability, as well as high prevalence of asymmetry between right and left body side.


#10 Vision in high-level football officials
Reference: PLoS One. 2017 Nov 21;12(11):e0188463. doi: 10.1371/journal.pone.0188463. eCollection 2017.
Authors: Baptista AMG, Serra PM, McAlinden C, Barrett BT
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5697857/pdf/pone.0188463.pdf
Summary: Officiating in football depends, at least to some extent, upon adequate visual function. However, there is no vision standard for football officiating and the nature of the relationship between officiating performance and level of vision is unknown. As a first step in characterising this relationship, we report on the clinically-measured vision and on the perceived level of vision in elite-level, Portuguese football officials. Seventy-one referees (R) and assistant referees (AR) participated in the study, representing 92% of the total population of elite level football officials in Portugal in the 2013/2014 season. Nine of the 22 Rs (40.9%) and ten of the 49 ARs (20.4%) were international-level. Information about visual history was also gathered. Perceived vision was assessed using the preference-values-assigned-to-global-visual-status (PVVS) and the Quality-of-Vision (QoV) questionnaire. Standard clinical vision measures (including visual acuity, contrast sensitivity and stereopsis) were gathered in a subset (n = 44, 62%) of the participants. Data were analysed according to the type (R/AR) and level (international/national) of official, and Bonferroni corrections were applied to reduce the risk of type I errors. Adopting criterion for statistical significance of p<0.01, PVVS scores did not differ between R and AR (p = 0.88), or between national- and international-level officials (p = 0.66). Similarly, QoV scores did not differ between R and AR in frequency (p = 0.50), severity (p = 0.71) or bothersomeness (p = 0.81) of symptoms, or between international-level vs national-level officials for frequency (p = 0.03) or bothersomeness (p = 0.07) of symptoms. However, international-level officials reported less severe symptoms than their national-level counterparts (p<0.01). Overall, 18.3% of officials had either never had an eye examination or if they had, it was more than 3 years previously. Regarding refractive correction, 4.2% had undergone refractive surgery and 23.9% wear contact lenses when officiating. Clinical vision measures in the football officials were similar to published normative values for young, adult populations and similar between R and AR. Clinically-measured vision did not differ according to officiating level. Visual acuity measured with and without a pinhole disc indicated that around one quarter of participants may be capable of better vision when officiating, as evidenced by better acuity (≥1 line of letters) using the pinhole. Amongst the clinical visual tests we used, we did not find evidence for above-average performance in elite-level football officials. Although the impact of uncorrected mild to moderate refractive error upon officiating performance is unknown, with a greater uptake of eye examinations, visual acuity may be improved in around a quarter of officials.


#11 Monitoring the effect of football match congestion on hamstring strength and lower limb flexibility: Potential for secondary injury prevention?
Reference: Phys Ther Sport. 2017 Sep 15;29:14-18. doi: 10.1016/j.ptsp.2017.09.001. [Epub ahead of print]
Authors: Wollin M, Thorborg K, Pizzari T
Summary: The purpose was to investigate the effect of competitive football match congestion on hamstring strength and lower limb flexibility. Fifteen male elite youth football players from the national football association centre of excellence were included (age = 15.81 ±0.65 years, height = 171.95 ±6.89 cm, weight = 65.93 ±7.53 kg). Hamstring strength and pain, ankle dorsiflexion, hip extension, knee extension and flexion range of motion were used as main outcome measures. Hamstring strength was highest at baseline and significantly reduced at 24 (p = 0.001, mean difference -0.19 Nm/Kg, CI95 -0.28, -0.1) and 48 h post-match 1 (p = 0.002, mean difference -0.16 Nm/Kg, CI95 -0.25, -0.07). Strength recovered by match day 2 before significantly reducing again 24 h post-match 2 (p = 0.012, mean difference -0.17 Nm/Kg, CI95 -0.29, -0.04). Pain was lowest at baseline and increased in the post-match periods (p < 0.05) with standardised effect sizes ranging from 0.07 to 0.42. Passive knee flexion range decreased post-match (p < 0.01) with mean differences of 1.5°-2.7°. The other flexibility measures remained unaffected by match play. Isometric hamstring strength and pain can be considered for inclusion in-season to monitor player's post-match hamstring recovery characteristics during congested match fixtures.


#12 Alcohol intoxication at Swedish football matches: A study using biological sampling to assess blood alcohol concentration levels among spectators
Reference: PLoS One. 2017 Nov 20;12(11):e0188284. doi: 10.1371/journal.pone.0188284. eCollection 2017.
Authors: Durbeej N, Elgan TH, Jalling C, Gripenberg J
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5695776/pdf/pone.0188284.pdf
Summary: Alcohol use and alcohol-related problems, including accidents, vandalism and violence, at sporting events are of increased concern in Sweden and other countries. The relationship between alcohol use and violence has been established and can be explained by the level of intoxication. Given the occurrence of alcohol use and alcohol-related problems at sporting events, research has assessed intoxication levels measured through biological sampling among spectators. This cross-sectional study aimed to assess the level of alcohol intoxication among spectators at football matches in the Swedish Premier Football League. Spectators were randomly selected and invited to participate in the study. Alcohol intoxication was measured with a breath analyser for Blood Alcohol Concentration levels, and data on gender, age, and recent alcohol use were gathered through a face-to-face interview. Blood Alcohol Concentration samples from 4420 spectators were collected. Almost half (46.8%) had a positive Blood Alcohol Concentration level, with a mean value of 0.063%, while 8.9% had a Blood Alcohol Concentration level ≥ 0.1%, with a mean value of 0.135%. Factors that predicted a higher Blood Alcohol Concentration level included male gender (p = 0.005), lower age (p < 0.001), attending a local derby (p < 0.001), alcohol use prior to having entered the arena (p < 0.001), attending a weekend match (p < 0.001), and being a spectator at supporter sections (p < 0.001). About half of all spectators at football matches in the Swedish Premier Football League drink alcohol in conjunction with the match. Approximately one tenth have a high level of alcohol intoxication.


#13 Longitudinal improvement in Balance Error Scoring System scores among NCAA Division-I football athletes
Reference: J Neurotrauma. 2017 Nov 17. doi: 10.1089/neu.2017.5072. [Epub ahead of print]
Authors: Mathiasen RE, Hogrefe CP, Harland KK, Peterson A, Smoot K
Summary: The Balance Error Scoring System (BESS) is a commonly used concussion assessment tool. Recent studies have questioned the stability and reliability of baseline BESS scores. The purpose of this longitudinal prospective cohort study is to examine differences in yearly baseline BESS scores in athletes participating on an NCAA Division-I football team. NCAA Division-I freshman football athletes were videotaped performing the BESS test at matriculation and following one year of participation in the football program. Twenty-three athletes were enrolled in year one of the study, and twenty-five athletes were enrolled in year two. Those athletes enrolled in year one were again videotaped following year two of the study. The paired t-test was used to assess for change in score over time for the firm surface, foam surface, and the cumulative BESS score. Additionally, inter- and intra-rater reliability values were calculated. Cumulative errors on the BESS significantly decreased from a mean of 20.3 at baseline to 16.8 after one year of participation. The mean number of errors following the second year of participation was 15.0. Inter-rater reliability for the cumulative score ranged from 0.65 to 0.75. Intra-rater reliability was 0.81. Following one year of participation, there is a statistically and clinically significant improvement in BESS scores in an NCAA Division-I football program. While additional improvement in the BESS scores was noted following the second year of participation, it did not reach statistical significance. Football athletes should undergo baseline BESS testing at least yearly if the BESS is to optimally useful as a diagnostic test for concussion.

Fri

08

Dec

2017

Football ist...(#47)

Crosses into the penalty box = ↑ chances of winning

Wed

06

Dec

2017

Football is...(#46)

Training according to players' positions.

Wed

29

Nov

2017

Latest research in football - week 47 - 2017

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 Z-scores-based methods and their application to biological monitoring: an example in professional soccer players
Reference: Biostatistics. 2017 Nov 15. doi: 10.1093/biostatistics/kxx044. [Epub ahead of print]
Authors: Sauliere G, Dedecker J, Marquet LA, Rochcongar P, Toussaint JF, Berthelot G
Summary: The clinical and biological follow-up of individuals, such as the biological passport for athletes, is typically based on the individual and longitudinal monitoring of hematological or urine markers. These follow-ups aim to identify abnormal behavior by comparing the individual's biological samples to an established baseline. These comparisons may be done via different ways, but each of them requires an appropriate extra population to compute the significance levels, which is a non-trivial issue. Moreover, it is not necessarily relevant to compare the measures of a biomarker of a professional athlete to that of a reference population (even restricted to other athletes), and a reasonable alternative is to detect the abnormal values by considering only the other measurements of the same athlete. Here we propose a simple adaptive statistic based on maxima of Z-scores that does not rely on the use of an extra population. We show that, in the Gaussian framework, it is a practical and relevant method for detecting abnormal values in a series of observations from the same individual. The distribution of this statistic does not depend on the individual parameters under the null hypothesis, and its quantiles can be computed using Monte Carlo simulations. The proposed method is tested on the 3-year follow-up of ferritin, serum iron, erythrocytes, hemoglobin, and hematocrit markers in 2577 elite male soccer players. For instance, if we consider the abnormal values for the hematocrit at a 5% level, we found that 5.57% of the selected cohort had at least one abnormal value (which is not significantly different from the expected false-discovery rate). The approach is a starting point for more elaborate models that would produce a refined individual baseline. The method can be extended to the Gaussian linear model, in order to include additional variables such as the age or exposure to altitude. The method could also be applied to other domains, such as the clinical patient follow-up in monitoring abnormal values of biological markers.


#2 Effects of detraining on breathing pattern and ventilatory efficiency in young soccer players
Reference: J Sports Med Phys Fitness. 2017 Nov 17. doi: 10.23736/S0022-4707.17.07619-8. [Epub ahead of print]
Authors: Alvero Cruz JR, Ronconi M, Garcia Romero J, Naranjo Orellana J
Summary: This study investigated the effects of detraining on breathing pattern. The aim of this study was to evaluate the effect of a sixweek detraining period on breathing patterns and ventilatory efficiency. Fourteen young soccer players were evaluated at the end of a competitive season and after a sixweek detraining period. Assessment of respiratory efficiency was based on VE/VCO2 slope changes below 70% of exercise intensity. All participants underwent twice an incremental graded exercise test up to exhaustion. No differences in breathing frequency and inspiratory time/ total time ratio (Ti/Ttot) were found after detraining (p>.05). Differences in tidal volume (VT), VT/Ti quotient and VE were significant (p<.05) at between 40 to 100% of exercise intensity. The VE/VCO2 slope did not change (p>.05) during a postdetraining maximal incremental test. A sixweek detraining period causes changes in inspiratory flow but does not affect the inspiratory time/total respiratory cycle time ratio. The overall ventilatory efficiency of the respiratory system remains constant and is not affected by detraining.


#3 Acoustic Analysis of Soccer Fans in Acute Phonotrauma After the Match
Reference: J Voice. 2017 Nov 13. pii: S0892-1997(17)30294-1. doi: 10.1016/j.jvoice.2017.10.004. [Epub ahead of print]
Authors: Pinarbasli MO, Kaya E, Ozudogru E, Gurbuz MK, Colak E, Aksoy MA, Birdane L, Guney FO
Summary: Acute phonotrauma is the result of sound production by shouting or straining one's voice. In this study, we aimed to investigate the acute changes in the vocal folds and voices of soccer fans who voluntarily applied to our clinic after the soccer match where they engaged in acute phonotrauma. There are no other studies in the literature conducted on a similar sample group. Videolaryngostroboscopic (VLS) examination, acoustic voice analysis, and Voice Handicap Index (VHI) questionnaire were performed on 29 voluntary soccer fans included to the study before the match and at the first hour after the match. The values obtained were compared statistically with each other and with 29 control groups without voice pathology. The jitter, shimmer, and normalized noise energy values measured after the match increased significantly statistically compared with the pre-match level, but harmonic noise ratio value decreased significantly (P < 0.05). VHI scores increased significantly after the match according to the pre-match scores (P < 0.05). In the VLS examinations, there was no difference in the images before and after the match. It has been concluded that people who are using their voices loudly and intensely by shouting during the match are exposed to sound changes after the match, and if this situation becomes persistent, it may cause permanent voice pathologies. It is thought that VHI and acoustic voice analysis should be done together with VLS for diagnosis and follow-up of voice changes for which the VLS examination alone is not sufficient.


#4 Sex Differences in Aerobic Fitness in Top-Class Soccer Referees
Reference: J Strength Cond Res. 2017 Nov 14. doi: 10.1519/JSC.0000000000002292. [Epub ahead of print]
Authors: Castagna C, Bizzini M, DʼOttavio S, Araujo Povoas SC
Summary: The aim of this study was to assess the aerobic-fitness differences between male and female top-class soccer field referees (FRs). This with the purpose to provide cutoff values useful for training prescription in female FRs. Forty female top-class FRs (age 34.18 ± 3.50 years and 5 ± 3.9 years international refereeing experience) and 52 male FRs (age 38.4 ± 3.3 years and 5 ± 3.5 years international refereeing experience) candidates in the preliminary open list developed by the FIFA Refereeing Department for the 2014 and 2015 World Cup Tournaments, participated in the study. The FRs were tested for aerobic fitness under laboratory conditions with a progressive speed treadmill test until exhaustion. Female FRs showed to possess, on average, lower (large effect) levels of aerobic fitness and performance compared with their male counterparts. The female FRs' V[Combining Dot Above]O2max (48.1 ± 4.4 ml·kg·min) was 7% (large effect) lower than the male FRs (51.9 ml·kg·min). Peak treadmill speed was 11% lower (large effect) in female FRs (16.27 ± 0.94 vs. 14.64 ± 0.96 km·h). The receiver operating characteristic curve analysis enabled cutoff values (47.8 ml·kg·min for V[Combining Dot Above]O2max) that may be used as preliminary cues to guide physiological selection and training prescription in female FRs aiming to officiate male-soccer matches. Only 2.5% of the female FRs showed V[Combining Dot Above]O2max higher than the mean values of male FRs when using the scaled notation (0.68). Female FRs aiming to officiate male competitions should consider training intensities at anaerobic threshold speed (13 km·h, 95% heart rate max) when developing aerobic fitness. Given the very large sex differences in aerobic performance, strength/power training should be proposed to perspective female top-class FRs.


#5 Return to Play After Hip Arthroscopic Surgery for Femoroacetabular Impingement in Professional Soccer Players
Reference: Am J Sports Med. 2017 Nov 1:363546517738741. doi: 10.1177/0363546517738741. [Epub ahead of print]
Authors: Locks R, Utsunomiya H, Briggs KK, McNamara S, Chahla J, Philippon MJ
Summary: Arthroscopic hip surgery has been shown to be effective in returning professional athletes back to play at a high level of performance in different sports. Limited information exists regarding professional soccer players and their return to play. The purpose of the study was to determine the rate and time to return to sport for professional soccer players after hip arthroscopic surgery for the treatment of femoroacetabular impingement (FAI) and to identify possible risk factors associated with a delay in returning to play. Professional soccer players who underwent hip arthroscopic surgery for FAI by a single surgeon between 2005 and 2015 were evaluated. Data retrieved from www.mlssoccer.com , www.fifa.com , www.transfermarkt.co.uk , and www.wikipedia.org included information on each player's professional career, participation on the national team, length of professional career before surgery, number of appearances (games) before surgery, time between surgery and first appearance in a professional game, and number of appearances after surgery. Other data were obtained from the patient's medical records. Twenty-four professional soccer players (26 hips) were included. The mean age at surgery was 25.0 ± 4.0 years (range, 19-32 years). A total of 96% of patients were able to return to play at the professional level. The mean time between surgery and the first professional game played was 9.2 months (range, 1.9-24.0 months). On average, players played in 70 games after surgery (range, 0-224). National team players were able to return to play significantly earlier than the rest of the players (median, 5.7 months vs 11.6 months, respectively; P = .018). Severe chondral damage and microfracture did not interfere with return to play. The arthroscopic management of FAI in symptomatic professional soccer players allowed 96% of them to return to play. Players with national team experience were able to return to play earlier than those without it. Severe chondral damage and microfracture did not interfere with return to play.


#6 Effects of an Interpersonal Style Intervention for Coaches on Young Soccer Players' Motivational Processes
Reference: J Hum Kinet. 2017 Oct 20;59:107-120. doi: 10.1515/hukin-2017-0151. eCollection 2017 Oct.
Authors: Pulido JJ, Sanchez-Oliva D, Leo FM, Matos S, Garcia-Calvo T
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5680690/pdf/hukin-59-107.pdf
Summary: The main goal of the study was to assess the effects of an intervention programme developed with soccer coaches, based on promoting strategies to optimise the satisfaction of the basic psychological needs of athletes. Eight soccer coaches, aged between 19 and 50 years (M = 32.5; SD = 14.34), participated in the study. They were selected intentionally (without academic or federative training) and divided equally into a control and an experimental group by random peer selection. Also, 109 soccer players, aged between 11 and 15 years (M = 13.78; SD = 1.38), divided into a control group (CG; n = 56) and an experimental group (EG; n = 53), participated in the experiment. The training programme (12 hours) was aimed to develop methodological and motivational strategies to promote autonomy, competence and relatedness need satisfaction among the players. The results showed that the participants in the EG decreased competence and relatedness control, while significantly increased (post-intervention) competence and relatedness needs satisfaction. Moreover, values for the EG did not decrease for autonomy, competence frustration and amotivation, while they increased for the sport commitment. Also, intrinsic motivation decreased in both groups (greater decrease in the CG). In conclusion, we can affirm the effectiveness of the training programme to create an environment of "bright side" motivation, and reduce thwarting styles, needs frustration and low self-determination levels.


#7 Mental Strategies Predict Performance and Satisfaction with Performance among Soccer Players
Reference: J Hum Kinet. 2017 Oct 20;59:79-90. doi: 10.1515/hukin-2017-0149. eCollection 2017 Oct.
Authors: Kruk M, Blecharz J, Boberska M, Zarychta K, Luszczynska A
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5680688/pdf/hukin-59-079.pdf
Summary: This study investigated the changes in mental strategies across the season and their effects on performance and satisfaction with individual performance. Data were collected three times: at the pre-season at Time 1 (T1; baseline), in the mid-season at Time 2 (T2; two-month follow-up), and at the end-of-season at Time 3 (T3; nine-month follow-up) among male soccer players (N = 97) aged 16-27. Athletes completed the questionnaires assessing the use of nine psychological strategies in competition and the level of satisfaction with individual performance. Endurance performance was measured objectively with a 300 m run. A high level of relaxation (T1) explained better 300 m run performance (T3) and a high level of self-talk explained a higher satisfaction with individual performance (T3). A rare use of distractibility and emotional control (T1) predicted a higher level of satisfaction with individual performance (T3). No predictive role of other psychological strategies was found. The use of emotional control, relaxation, and distractibility increased over the season, whereas the use of imagery and negative thinking declined. Besides the roles of self-talk, imagery, relaxation and goal-setting, the effects of distractibility and emotional control should be taken into account when considering athletes' mental training programs.


#8 Low perceptual sensitivity to altered video speed in viewing a soccer match
Reference: Sci Rep. 2017 Nov 13;7(1):15379. doi: 10.1038/s41598-017-15619-8.
Authors: de'Sperati C, Baud Bovy G
Download link: https://www.nature.com/articles/s41598-017-15619-8.pdf
Summary: When watching videos, our sense of reality is continuously challenged. How much can a fundamental dimension of experience such as visual flow be modified before breaking the perception of real time? Here we found a remarkable indifference to speed manipulations applied to a popular video content, a soccer match. In a condition that mimicked real-life TV watching, none of 100 naïve observers spontaneously noticed speed alterations up/down to 12%, even when asked to report motion anomalies, and showed very low sensitivity to video speed changes (Just Noticeable Difference, JND = 18%). When tested with a constant-stimuli speed discrimination task, JND was still high, though much reduced (9%). The presence of the original voice-over with compensation for pitch did not affect perceptual performance. Thus, our results document a rather broad tolerance to speed manipulations in video viewing, even under attentive scrutiny. This finding may have important implications. For example, it can validate video compression strategies based on sub-threshold temporal squeezing. This way, a soccer match can last only 80 min and still be perceived as natural. More generally, knowing the boundaries of natural speed perception may help to optimize the flow of artificial visual stimuli which increasingly surround us.


#9 A prospective investigation to evaluate risk factors for lower extremity injury risk in male youth soccer players
Reference: Scand J Med Sci Sports. 2017 Nov 11. doi: 10.1111/sms.13013. [Epub ahead of print]
Authors: Read PJ, Oliver JL, De Ste Croix MBA, Myer GD, Lloyd RS
Summary: There is an inherent risk of injury in male youth football; however, pertinent risk factors for injury have yet to be examined. This study used a prospective cohort design with 357 elite male youth football players (aged 10-18 years) assessed during the pre-season period and then monitored during the season recording all non-contact lower extremity injuries. Screening tests included: single leg hop for distance (SLHD); 75% of maximum hop and stick (75%Hop); single leg countermovement jump (SLCMJ); and the tuck jump assessment (TJ). Players were divided into sub-groups based on chronological age. SLCMJ peak landing vertical ground reaction force (pVGRF) asymmetry was the most prominent risk factor (U11-U12's, OR 0.90, p = 0.04; and U15-U16's, OR 0.91, p < 0.001). Maturational offset (OR 0.58, p = 0.04), lower right leg SLCMJ pVGRF relative to body weight (OR 0.36, p = 0.03) and advanced chronological age (OR 3.62, p = 0.04) were also significantly associated with heightened injury risk in the U13-U14's, U15-U16's and U18's respectively. Univariate analyses showed combinations of anthropometric and movement screening risk factors were associated with heightened risk of lower extremity injury; however, there was variability across the different chronological age groups. Greater SLCMJ pVGRF asymmetry, lower right leg SLCMJ pVGRF %BW, later maturation and advanced chronological age are potential risk factors for injury in elite male youth football players, although the strength of these relationships were often low to moderate. In addition, risk factors are likely to change at different stages of development.


#10 Kinematic analysis of pressing situations in female collegiate football games: New insight into ACL injury causation
Reference: Scand J Med Sci Sports. 2017 Nov 16. doi: 10.1111/sms.13018. [Epub ahead of print]
Authors: Sasaki S, Koga H, Krosshaug T, Kaneko S, Fukubayashi T
Summary: The most common events during which anterior cruciate ligament (ACL) injuries occur in football are pressing situations. This study aimed to describe the knee and hip joint kinematics during pressing situations in football games in order to identify kinematic patterns in actions with a high risk for ACL injuries. We filmed 5 female collegiate football matches and identified 66 pressing situations. Five situations with a large distance between the trunk and foot placements in the sagittal plane were analysed using a model-based image-matching technique. The mean knee flexion angle at initial contact (IC) was 13° (range, 8°-28°), and increased by 11° (95% confidence interval [CI], 3°-14°) at 40 ms after IC. As for knee adduction and rotation angles, the knee positions were close to neutral at IC, and only minor knee angular changes occurred later in the sequences. The mean hip flexion was 25° (range, 8°-43°) at IC, and increased by 22° (95% CI, 11°-32°) after 100 ms. The hip was also externally rotated by 7° (range, -19° to 3°) at IC, and gradually rotated internally, reaching 10° of internal rotation (range, -5° to 27°) at 100 ms after IC. This study suggests that the observed knee valgus, internal hip and knee rotation, and static hip flexion previously reported in non-contact ACL injury events are unique to injury situations. In contrast, neither rapid knee valgus nor increased internal rotation was seen in non-injury pressing manoeuvres.


#11 The prognostic value of physiological and physical characteristics in youth soccer: A systematic review
Reference: Eur J Sport Sci. 2017 Nov 21:1-13. doi: 10.1080/17461391.2017.1386719. [Epub ahead of print]
Authors: Murr D, Raabe J, Honer O
Download link: http://www.tandfonline.com/doi/abs/10.1080/17461391.2017.1386719?needAccess=true#aHR0cDovL3d3dy50YW5kZm9ubGluZS5jb20vZG9pL3BkZi8xMC4xMDgwLzE3NDYxMzkxLjIwMTcuMTM4NjcxOT9uZWVkQWNjZXNzPXRydWVAQEAw
Summary: Talent identification and selection in soccer is typically based on subjective evaluations of experienced coaches. Recently, there has been a trend to complement these subjective assessments with objective tests. However, there is currently no comprehensive overview of the prognostic relevance of objective measurements in youth soccer. Therefore, the primary purpose of the current study was to systematically review published empirical studies related to the prognostic relevance of physiological (e.g. endurance and speed) and physical characteristics (i.e. height and weight). Of 6876 initially identified studies, nine articles were included. In those studies, endurance (nine studies), change of direction (seven), height (seven), and weight (seven) received the most meaningful consideration within the literature. In regard to physiological predictors, between 16 and 29 effect sizes were tested for endurance, sprint, and change of direction, and about half of them were found to be significant with small to moderate effects (0.37 ≤ Mdn(d) ≤ 0.57). In addition, while only investigated in two studies all tested effect sizes for repeated sprint ability were found to be significant. Despite their frequent consideration in the literature, low numbers of significant effect sizes (≤ 26%) and magnitude (0.23 ≤ Mdn(d) ≤ 0.29) were found for the physical predictors height and weight. Overall, results appear to be dependent on the respective study design and, in particular, moderator variables (i.e. soccer development stage, performance level T1/T2, prognostic period, and sample size). Consequently, additional research seems warranted to more comprehensively investigate the predictive relevance of the individual characteristics using more homogeneous study designs.



American Football
#1 Associations between BMI Change and Cardiometabolic Risk in Retired Football Players
Reference: Med Sci Sports Exerc. 2017 Nov 14. doi: 10.1249/MSS.0000000000001492. [Epub ahead of print]
Authors: Trexler ET, Smith-Ryan AE, DeFreese JD, Marshall SW, Guskiewicz KM, Kerr ZY
Summary: Elevated rates of cardiometabolic diseases have been observed in former American football players. The current study sought to determine if change in body mass index (ΔBMI) following retirement influences the prevalence of coronary heart disease (CHD), diabetes, or high blood pressure (HBP) in former professional football players. Retired professional football players (n=3,729) were sent a survey with questions regarding health status, playing history, and demographic information. Self-reported BMI at the time of retirement was subtracted from current self-reported BMI to calculate ΔBMI. Prevalence of CHD, diabetes, and HBP were determined by asking participants if they had ever been diagnosed by a healthcare professional. Binomial regression with a Poisson residual and robust variance estimation was used to compute crude prevalence ratios (PRs) and 95% confidence intervals (CI) for each outcome. Adjusted PRs were calculated by adjusting for BMI at the time of retirement, age, years of football experience, race, exercise habits, alcohol use, steroid history, smoking history, and playing position. Complete data were available for 2,062 respondents. Prevalence of CHD increased 25-31% for each 5-point increase in ΔBMI following retirement (Crude PR: 1.25; 95%CI: 1.03-1.52; p=0.026; Adjusted PR: 1.31; 95%CI: 1.11-1.55; p=0.001). Diabetes prevalence increased 69-88% for each 5-point ΔBMI increase (Crude: 1.88; 95%CI: 1.45-2.44; p<0.001; Adjusted: 1.69; 95%CI: 1.32-2.15; p<0.001). A 5-point increase in ΔBMI was associated with a 35-40% increase in HBP prevalence (Crude: 1.40; 95%CI: 1.27-1.53; p<0.001; Adjusted: 1.35; 95%CI: 1.24-1.47; p<0.001). After controlling for relevant covariates, post-retirement ΔBMI was positively and independently associated with prevalence of CHD, diabetes, and HBP. Post-retirement interventions using diet and/or exercise to influence body composition may improve long-term health in retired football players.


#2 Calling Injury Timeouts for the Medical Evaluation of Concussion: Determinants of Collegiate Football Officials' Behavior
Reference: J Athl Train. 2017 Nov 8. doi: 10.4085/1062-6050-52.11.17. [Epub ahead of print]
Authors: Kroshus E, Parsons J, Hainline B
Summary: Sports officials can play an important role in concussion safety by calling injury timeouts so that athletic trainers can evaluate athletes with possible concussions. Understanding the determinants of whether officials call an injury timeout when they suspect a concussion has important implications for the design of interventions that better support officials in this role. The objective of the study was to assess the knowledge of US collegiate football officials about concussion symptoms and to determine the associations between knowledge, perceived injunctive norms, and self-efficacy and calling injury timeouts for suspected concussions in athletes. 3074 US collegiate football officials contacted, 1324 (43% response rate) participated.  Concussion knowledge, injunctive norms (belief about what others would want them to do), and behavioral self-efficacy (confidence in their ability to call injury timeouts for suspected concussions in athletes during challenging game-day conditions) were used as outcome measures. Officials reported calling approximately 1 injury timeout for a suspected concussion every 4 games during the 2015 season. Structural equation modeling indicated that officials with more concussion-symptom knowledge had greater behavioral self-efficacy. Independent of an official's symptom knowledge, injunctive norms that were more supportive of calling an injury timeout were associated with greater self-efficacy. Concussion education for officials is important because when officials are aware of concussion symptoms, they are more confident in calling injury timeouts. Beyond increasing symptom knowledge, fostering sports environments that encourage concussion safety in all stakeholder groups can support officials in calling injury timeouts. Athletic trainers can help create sports environments that support proactive concussion identification by educating stakeholders, including officials, about the importance of concussion safety. When officials believe that other stakeholders support concussion safety, they are more likely to call injury timeouts if they suspect a concussion has occurred.


#3 Postmortem Autopsy-Confirmation of Antemortem [F-18]FDDNP-PET Scans in a Football Player With Chronic Traumatic Encephalopathy
Reference: Neurosurgery. 2017 Nov 10. doi: 10.1093/neuros/nyx536. [Epub ahead of print]
Authors: Omalu B, Small GW, Bailes J, Ercoli LM, Merrill DA, Wong KP, Huang SC, Satyamurthy N, Hammers JL, Lee J, Fitzsimmons RP, Barrio JR
Summary: Currently, only presumptive diagnosis of chronic traumatic encephalopathy (CTE) can be made in living patients. We present a modality that may be instrumental to the definitive diagnosis of CTE in living patients based on brain autopsy confirmation of [F-18]FDDNP-PET findings in an American football player with CTE. [F-18]FDDNP-PET imaging was performed 52 mo before the subject's death. Relative distribution volume parametric images and binding values were determined for cortical and subcortical regions of interest. Upon death, the brain was examined to identify the topographic distribution of neurodegenerative changes. Correlation between neuropathology and [F-18]FDDNP-PET binding patterns was performed using Spearman rank-order correlation. Mood, behavioral, motor, and cognitive changes were consistent with chronic traumatic myeloencephalopathy with a 22-yr lifetime risk exposure to American football. There were tau, amyloid, and TDP-43 neuropathological substrates in the brain with a differential topographically selective distribution. [F-18]FDDNP-PET binding levels correlated with brain tau deposition (rs = 0.59, P = .02), with highest relative distribution volumes in the parasagittal and paraventricular regions of the brain and the brain stem. No correlation with amyloid or TDP-43 deposition was observed. [F-18]FDDNP-PET signals may be consistent with neuropathological patterns of tau deposition in CTE, involving areas that receive the maximal shearing, angular-rotational acceleration-deceleration forces in American football players, consistent with distinctive and differential topographic vulnerability and selectivity of CTE beyond brain cortices, also involving midbrain and limbic areas. Future studies are warranted to determine whether differential and selective [F-18]FDDNP-PET may be useful in establishing a diagnosis of CTE in at-risk patients.


#4 Intracranial Ischemic Infarct Due to Blunt Force Trauma in a High School Football Player
Reference: Cureus. 2017 Sep 7;9(9):e1659. doi: 10.7759/cureus.1659.
Authors: Esianor BI, Haider AS, Engelhardt MI, Osumah T, Vayalumkal S, Thakur R, Leonard D, Haithcock J, Layton KF
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5675602/pdf/cureus-0009-00000001659.pdf
Summary: Ischemic stroke is an uncommon cause of death among teenagers and young adults; however, the etiologies differ when compared to ischemic strokes in older individuals. Large-vessel atherosclerosis and small-vessel disease causing ischemic stroke are rare for the teenage population, while cervicocerebral arterial dissections account for up to 20% of ischemic strokes. Here, we present the case of a 16-year-old male who developed internal carotid artery dissection (ICAD) after a head injury and subsequently developed ischemic stroke and seizures.


#6 Posterolateral Corner Injuries of the Knee at the National Football League Combine: An Imaging and Outcomes Analysis
Reference: Arthroscopy. 2017 Nov 13. pii: S0749-8063(17)31162-3. doi: 10.1016/j.arthro.2017.08.303. [Epub ahead of print]
Authors: Chahla J, Kennedy NI, Cinque ME, Sanchez G, Logan C, Vopat BG, Beaulieu-Jones B, Price M, Whalen J, LaPrade RF, Provencher MT
Summary: (1) To determine the epidemiology, examination findings, imaging findings, and associated injuries of posterolateral corner (PLC) injuries in players participating in the National Football League (NFL) Combine and (2) to evaluate the impact of PLC injuries on performance compared with matched controls. All PLC injuries identified at the NFL Combine between 2009 and 2015 were reviewed. The inclusion criteria were any player who had clinical findings or a previous surgical procedure consistent with a PLC injury and who participated in medical and performance testing at the NFL Combine. PLC injuries were identified by evaluating the side-to-side difference in lateral-compartment laxity with varus stress and reviewing magnetic resonance imaging studies. NFL performance outcomes (draft position and number of games played or started within the first 2 years) were compared with matched controls. Of the 2,285 players assessed at the NFL Combine, 16 (0.7%) were identified with a history of a grade II or III PLC tear and surgical management whereas 7 additional players (0.3%) had a PLC injury diagnosed on clinical examination, for 23 total PLC injuries (1%). On examination, 13 of 22 knees (59%) were shown to be stable; however, most of those managed surgically had significantly improved stability (13 of 15 stable) versus none of those managed nonsurgically (0 of 7 stable). Surgically managed PLC-injured athletes started significantly fewer games than controls (5.3 vs 10.5, P = .03); the mean draft position for players with surgically treated PLC injuries was 139.7 versus controls' mean draft position of 111.3. Of the 16 athletes treated operatively, 2 reported a PLC injury recurrence; both were managed nonoperatively. A small percentage of players at the NFL Combine had evidence of a previous PLC injury (1%), with 0.4% having residual varus asymmetry on clinical examination. A worse overall mean draft position for isolated PLC-injured athletes versus controls was found: 132.8 versus 111.3 (P = .02). It is recommended that the use of varus stress radiographs be considered for NFL Combine athletes to objectively determine their grade of injury. LEVEL OF EVIDENCE: Level IV, retrospective case series.


Australian Football
#1 Phases of match-play in professional Australian Football: Descriptive analysis and reliability assessment
Reference: J Sci Med Sport. 2017 Oct 23. pii: S1440-2440(17)31671-7. doi: 10.1016/j.jsams.2017.10.021. [Epub ahead of print]
Authors: Rennie MJ, Watsford ML, Spurrs RW, Kelly SJ, Pine MJ
Summary: The purpose was to examine the frequency and time spent in the phases of Australian Football (AF) match-play and to assess the intra-assessor reliability of coding these phases of match-play. Video footage of 10 random quarters of AF match-play were coded by a single researcher. Phases of offence, defence, contested play, umpire stoppage, set shot and goal reset were coded using a set of operational definitions. Descriptive statistics were provided for all phases of match-play. Following a 6-month washout period, intra-coder reliability was assessed using typical error of measurement (TEM) and intra-class correlation coefficients (ICC). A quarter of AF match-play involved 128±20 different phases of match-play. The highest proportion of match-play involved contested play (25%), followed by offence (18%), defence (18%) and umpire stoppages (18%). The mean duration of offence, defence, contested play, umpire stoppage, set shot and goal reset were 14, 14, 10, 11, 28 and 47s, respectively. No differences were found between the two coding assessments (p>0.05). ICCs for coding the phases of play demonstrated very high reliability (r=0.902-0.992). TEM of the total time spent in each phase of play represented moderate to good reliability (TEM=1.8-9.3%). Coding of offence, defence and contested play tended to display slightly poorer TEMs than umpire stoppages, set shots and goal resets (TEM=8.1 vs 4.5%). Researchers can reliably code the phases of AF match-play which may permit the analysis of specific elements of competition.


#2 Eight Week Return to Play following Latarjet Shoulder Reconstruction in an Australian Football Player: A Case Report
Reference: J Sport Rehabil. 2017 Nov 15:1-28. doi: 10.1123/jsr.2017-0194. [Epub ahead of print]
Authors: Murphy M, Stockden M, Withers K, Breidahl W, Charlesworth J
Summary: Anterior shoulder dislocations are a common injury in many sports resulting in extended time lost from play with an extremely high recurrence rate in young athletes playing high risk sport. Latarjet shoulder reconstruction is a common surgical procedure used to prevent subsequent dislocation with an expected rehabilitation timeframe of between four to six months before return to play. A 21-year-old male Australian football player experienced two left sided shoulder dislocations before undergoing a left Latarjet shoulder reconstruction. He was assessed clinically and with magnetic resonance imaging which revealed significant tearing of the anterior labrum. We theorized maximal glenohumeral stability occurs after bony healing of the coracoid onto the glenoid at six weeks. The patient then underwent an eight-week structured and graduated rehabilitation program aimed at preventing loss of shoulder range of motion, muscle and functional capacity and returned to play at eight weeks post injury with no complications or recurrence at twelve month follow-up. This is the first time an eight-week rehabilitation following Latarjet shoulder reconstruction has been reported. In athletes with anterior glenohumeral dislocation who require accelerated return to play, a Latarjet reconstruction with an eight-week rehabilitation protocol can be considered.

Mon

27

Nov

2017

Football is...(#45)

Coach feedback to influence intensity

Fri

24

Nov

2017

Football is ...(#44)

Inter-player, inter-team and inter-line = team's tactical orientation

Thu

23

Nov

2017

Football is ...(#43)

End of warm-up = ballistic stretching with SSC activity

Wed

22

Nov

2017

Latest research in football - week 46 - 2017

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 Hamstring Injuries in Professional Soccer Players: Extent of MRI-Detected Edema and the Time to Return to Play
Reference: Sports Health. 2017 Nov 1:1941738117741471. doi: 10.1177/1941738117741471. [Epub ahead of print]
Authors: Crema MD, Godoy IRB, Abdalla RJ, de Aquino JS, Ingham SJM, Skaf AY
Summary: Discrepancies exist in the literature regarding the association of the extent of injuries assessed on magnetic resonance imaging (MRI) with recovery times. Thr hypothesis was that MRI-detected edema in grade 1 hamstring injuries does not affect the return to play (RTP). Grade 1 hamstring injuries from 22 professional soccer players were retrospectively reviewed. The extent of edema-like changes on fluid-sensitive sequences from 1.5-T MRI were evaluated using craniocaudal length, percentage of cross-sectional area, and volume. The time needed to RTP was the outcome. Negative binomial regression analysis tested the measurements of MRI-detected edema-like changes as prognostic factors. The mean craniocaudal length was 7.6 cm (SD, 4.9 cm; range, 0.9-19.1 cm), the mean percentage of cross-sectional area was 23.6% (SD, 20%; range, 4.4%-89.6%), and the mean volume was 33.1 cm3 (SD, 42.6 cm3; range, 1.1-161.3 cm3). The mean time needed to RTP was 13.6 days (SD, 8.9 days; range, 3-32 days). None of the parameters of extent was associated with RTP. The extent of MRI edema in hamstring injuries does not have prognostic value.


#2 Hip Strength as a Predictor of Ankle Sprains in Male Soccer Players: A Prospective Study
Reference: J Athl Train. 2017 Nov 8. doi: 10.4085/1062-6050-52.11.18. [Epub ahead of print]
Authors: Powers CM, Ghoddosi N, Straub RK, Khayambashi K
Summary: Diminished hip-abductor strength has been suggested to increase the risk of noncontact lateral ankle sprains. The purpose was to determine prospectively whether baseline hip-abductor strength predicts future noncontact lateral ankle sprains in competitive male soccer players. Two hundred ten competitive male soccer players participated in this study.  Before the start of the sport season, isometric hip-abductor strength was measured bilaterally using a handheld dynamometer. Any previous history of ankle sprains, body mass index, age, height, and weight was documented. During the sport season (30 weeks), ankle injury status was recorded by team medical providers. Injured athletes were further classified based on the mechanism of injury. Only data from injured athletes who sustained noncontact lateral ankle sprains were used for analysis. Postseason, logistic regression was used to determine whether baseline hip strength predicted future noncontact lateral ankle sprains. A receiver operating characteristic curve was constructed for hip strength to determine the cutoff value for distinguishing between high-risk and low-risk outcomes. A total of 25 noncontact lateral ankle sprains were confirmed, for an overall annual incidence of 11.9%. Baseline hip-abductor strength was lower in injured players than in uninjured players (P = .008). Logistic regression indicated that impaired hip-abductor strength increased the future injury risk (odds ratio = 1.10 [95% confidence interval = 1.02, 1.18], P = .010). The strength cutoff to define high risk was ≤33.8% body weight, as determined by receiver operating characteristic curve analysis. For athletes classified as high risk, the probability of injury increased from 11.9% to 26.7%. Reduced isometric hip-abductor strength predisposed competitive male soccer players to noncontact lateral ankle sprains.


#3 Nonsurgical Management of an Anterior Cruciate Ligament-Deficient Knee in a Women's Soccer Player: A Validation Clinical Case Report
Reference: J Athl Train. 2017 Nov 8. doi: 10.4085/1062-6050.52.11.21. [Epub ahead of print]
Authors: Gray CE, Hummel C, Lazenby T
Summary: A collegiate women's soccer player sustained an isolated anterior cruciate ligament (ACL) tear and expressed a desire to continue her season without surgical intervention. Using the results of a randomized controlled trial and published clinical guidelines, the clinicians classified the patient as an ACL-deficient coper. The patient completed her soccer season without incident, consistent with the findings of the established clinical guidelines. However, 6 months later, she sustained a meniscal tear, which was not unexpected given that 22% of ACL-deficient copers in the randomized controlled trial incurred a meniscal tear within 24 months of ACL injury.


#4 Risk Factors for Lower Extremity Overuse Injuries in Female Youth Soccer Players
Reference: Orthop J Sports Med. 2017 Oct 23;5(10):2325967117733963. doi: 10.1177/2325967117733963. eCollection 2017 Oct.
Authors: O'Kane JW, Neradilek M, Polissar N, Sabado L, Tencer A, Schiff MA
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5656111/pdf/10.1177_2325967117733963.pdf
Summary: Youth soccer injuries are common and of increasing concern, with sport specialization occurring at younger ages. Limited research is available regarding overuse injuries and risk factors in young female athletes. The purpose was to identify the number and rate of overuse injuries in female soccer players (ages 12-15 years), describe the anatomic location and type of injury, and evaluate contributing risk factors. A total of 351 female youth soccer players, ages 12 to 15 years, from Washington State were evaluated from 2008 to 2012. Players with lower extremity overuse injuries were identified through weekly emails and were interviewed by telephone to obtain data on injury type and body region. We evaluated the association between overuse injuries and preseason risk factors, including joint hypermobility, hip and knee muscle strength, and jump biomechanics, using Poisson regression to estimate relative risk (RR) and 95% CIs. The incidence rate for first-time lower extremity overuse injuries was 1.7 per 1000 athlete-exposure hours (AEH; 95% CI, 1.4-2.2), and that for repeat injuries was 3.4 per 1000 AEH (95% CI, 2.1-5.6). Knee injuries accounted for 47% of overuse injuries. Increased valgus was associated with a 3.2-fold increased risk (95% CI, 1.52-6.71) for knee injury. A 1-standard deviation (SD) increase in hamstring strength was associated with a 35% decreased risk (RR, 0.65; 95% CI, 0.46-0.91) for overuse knee injuries, and a 1-SD increase in quadriceps strength was associated with a 30% decreased risk (RR, 0.70; 95% CI, 0.50-0.98). A 1-SD increase in hip flexor strength was associated with a 28% decreased risk (RR, 0.72; 95% CI, 0.51-1.00) for overuse knee injuries, and a 1-SD increase in external rotation strength was associated with a 35% decreased risk (RR, 0.65; 95% CI, 0.46-0.91). Playing on more than 1 soccer team was associated with a 2.5-fold increased risk (95% CI, 1.08-5.35) for overuse knee injuries, and participating in other physical activities was associated with a 61% decreased risk (odds ratio, 0.39; 95% CI, 0.15-0.81). In this study, lower extremity overuse injuries in female youth soccer players affected primarily the knee. Lower knee separation distance, decreased lower extremity strength, and playing on more than 1 soccer team increased injury risk.


#5 Comparison of body fat percentage of male soccer players of different competitive levels, playing positions and age groups: a meta-analysis
Reference: J Sports Med Phys Fitness. 2017 Nov 7. doi: 10.23736/S0022-4707.17.07941-5. [Epub ahead of print]
Authors: Slimani M, Znazen H, Hammami A, Bragazzi NL
Summary: The aim of the present meta-analysis was to compare the body fat percentage (%) between male soccer players of different competitive levels, playing positions and age groups. The systematic search was conducted using different databases and according to the Population/Intervention or Exposure/Comparison/Outcome(s) [PICO] criteria. Higher % values of body fat in lower-level soccer players than higher-level counterparts (ES=0.18, 95% CI -0.86 to -0.14, p=0.006) were noted. Higher body fat % values in goalkeepers than defenders (ES=0.21, 95% CI -1.17 to -0.34, p<0.001), midfielders (ES=0.26, 95% CI -1.50 to -0.45, p<0.001) and forwards (ES=0.18, 95% CI -1.26 to -0.53, p<0.001) were observed. There was no significant association between % of body fat and age (p=0.86). In conclusion, body fat % clearly distinguished higher- from lower-level soccer players. These findings also imply that body fat % differ as a function of positional role in soccer and that sports scientists, coaches, and strength and conditioning professionals need to be aware of the specific positional requirements in soccer in terms of body fat. However, due to some limitations of the present meta-analysis (high statistically significant heterogeneity and evidence of publication bias), further studies are urgently needed in the field.


#6 Muscle injury rate in professional football is higher in matches played within 5 days since the previous match: a 14-year prospective study with more than 130000 match observations
Reference: Br J Sports Med. 2017 Nov 3. pii: bjsports-2016-097399. doi: 10.1136/bjsports-2016-097399. [Epub ahead of print]
Authors: Bengtsson H, Ekstrand J, Walden M, Hägglund M
Summary: The association between match congestion and injury rates in professional football has yielded conflicting results. The aim was to analyse associations between match congestion on an individual player level and injury rates during professional football matches. Data from a prospective cohort study of professional football with 133 170 match observations were analysed with Poisson regressions. Associations between short-term match congestion, defined as number of days between two match exposures (≤3, 4, 5, 6 and 7-10 days) and injury rates were analysed. To analyse the influence of long-term match congestion, defined as individual match exposure hours in the 30 days preceding a match, observations were categorised into three groups (low, ≤4.5; medium, >4.5 to ≤7.5; and high, >7.5 hours). No differences in total match injury rates were found between the reference category (≤3 days) and the other categories of short-term congestion. Muscle injury rates were significantly lower in matches preceded by 6 (rate ratio (RR) 0.79; 95% CI 0.65 to 0.95) or 7-10 days (RR 0.81; 95% CI 0.71 to 0.93) compared with ≤3 days since the last match exposure. No differences in total and muscle injury rates between the three long-term match congestion groups were found. In this study of male professional football players, there were no match congestion-related differences in total match injury rates, but muscle injury rates during matches were lower when players were given at least 6 days between their match exposures.


#7 Change in knee flexor torque after fatiguing exercise identifies previous hamstring injury in football players
Reference: Scand J Med Sci Sports. 2017 Nov 8. doi: 10.1111/sms.13007. [Epub ahead of print]
Authors: Lord C, Ma'ayah F, Blazevich AJ
Summary: Muscular fatigue and inter-limb strength asymmetry are factors known to influence hamstring injury risk, however limb-specific exacerbation of knee flexor (hamstrings) torque production after fatiguing exercise has previously been ignored. To investigate changes in muscular force production before and after sport-specific (repeated-sprint) and non-specific (knee extension-flexion) fatiguing exercise, and explore the sensitivity and specificity of isokinetic endurance (i.e. muscle-specific) and single-leg vertical jump (i.e. whole limb) tests to identify previous hamstring injury. 20 Western Australia State League footballers with previous unilateral hamstring injury and 20 players without participated. Peak concentric knee extensor and flexor (180°∙s-1 ) torques were assessed throughout an isokinetic endurance test, which was then repeated alongside a single-leg vertical jump test (SLVJ) before and after maximal repeated-sprint exercise. Greater reductions in isokinetic knee flexor torque (-16%) and the concentric hamstring:quadriceps peak torque ratio (-15%) were observed after repeated-sprint running only in the injured (kicking) leg and only in the previously injured subjects. Changes in (1) peak knee flexor torque after repeated-sprint exercise, and (2) the decline in knee flexor torque during the isokinetic endurance test measured after repeated-sprint exercise, correctly identified the injured legs (N=20) within the cohort (N=80) with 100% specificity and sensitivity. Decreases in peak knee flexor torque and knee flexor torque during an isokinetic endurance test after repeated-sprint exercise identified previous hamstring injury with 100% accuracy. Changes in knee flexor torque, but not SLVJ, should be tested to determine its prospective ability to predict hamstring injury in competitive football players.


#8 Effects of special exercise programs on functional movement screen scores and injury prevention in preprofessional young football players
Reference: J Exerc Rehabil. 2017 Oct 30;13(5):535-540. doi: 10.12965/jer.1735068.534. eCollection 2017 Oct.
Authors: Dinc E, Kilinc BE, Bulat M, Erten YT, Bayraktar B
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5667599/pdf/jer-13-5-535.pdf
Summary: To increase movement capacity and to reduce injury risk in young soccer players by implementing a special functional exercise program based on functional movement screen (FMS) and correctives. 67 young male athletes 14-19 years of age from a Super League Football Club Academy participated in the study. Functional movement patterns were evaluated with FMS assessment protocol. Deep squat, hurdle step, inline lunge, shoulder mobility, active straight leg raise, trunk stability push-up, and rotatory stability were examined in FMS. Considering the FMS scores the number of intervention and control groups were defined as 24 and 43, respectively. Intervention program was composed of 1 hr twice a week sessions in total of 12 weeks with 4 weeks of mobility, 4 weeks of stability, and 4 weeks of integration exercises. At the end of 12-week intervention and control groups were re-evaluated with FMS protocol. Contact and noncontact sports injuries recorded during one season. In intervention group there was statistically significant difference in increase in total FMS scores (P<0.01), deep squat (P≤0.001), hurdle step (P<0.05), inline lunge (P<0.01), and trunk stability push-up (P<0.01). In control group total FMS, deep squat, and trunk stability push-up scores increased with a statistical difference (P<0.01, P<0.05, P≤0.01, respectively). The incidence of noncontact injury in control group was higher than intervention group (P<0.05). Periodic movement screening and proper corrections with functional training is valuable in order to create better movement capacity to build better physical performance and more effective injury prevention.


#9 Heads Up: The Presentation of Schizoaffective Disorder in an Elite College Soccer Player with Prior Concussion
Reference: Harv Rev Psychiatry. 2017 Nov/Dec;25(6):302-310. doi: 10.1097/HRP.0000000000000147.
Authors: Adelsky SJ, Ducharme S, Wilner EK, Yudkoff B, Lejeune S.


American Football
#1 Is Big Truly Bad? Aortic Dilation in Former National Football League Players
Reference: Circ Cardiovasc Imaging. 2017 Nov;10(11). pii: e007157. doi: 10.1161/CIRCIMAGING.117.007157.
Authors: Churchill TW, Baggish AL


#2 Ascending Aortic Dimensions in Former National Football League Athletes
Reference: Circ Cardiovasc Imaging. 2017 Nov;10(11). pii: e006852. doi: 10.1161/CIRCIMAGING.117.006852.
Autors: Gentry JL 3rd, Carruthers D, Joshi PH, Maroules CD, Ayers CR, de Lemos JA, Aagaard P, Hachamovitch R, Desai MY, Roselli EE, Dunn RE, Alexander K, Lincoln AE, Tucker AM, Phelan DM
Summary: Ascending aortic dimensions are slightly larger in young competitive athletes compared with sedentary controls, but rarely >40 mm. Whether this finding translates to aortic enlargement in older, former athletes is unknown. This cross-sectional study involved a sample of 206 former National Football League (NFL) athletes compared with 759 male subjects from the DHS-2 (Dallas Heart Study-2; mean age of 57.1 and 53.6 years, respectively, P<0.0001; body surface area of 2.4 and 2.1 m2, respectively, P<0.0001). Midascending aortic dimensions were obtained from computed tomographic scans performed as part of a NFL screening protocol or as part of the DHS. Compared with a population-based control group, former NFL athletes had significantly larger ascending aortic diameters (38±5 versus 34±4 mm; P<0.0001). A significantly higher proportion of former NFL athletes had an aorta of >40 mm (29.6% versus 8.6%; P<0.0001). After adjusting for age, race, body surface area, systolic blood pressure, history of hypertension, current smoking, diabetes mellitus, and lipid profile, the former NFL athletes still had significantly larger ascending aortas (P<0.0001). Former NFL athletes were twice as likely to have an aorta >40 mm after adjusting for the same parameters. Ascending aortic dimensions were significantly larger in a sample of former NFL athletes after adjusting for their size, age, race, and cardiac risk factors. Whether this translates to an increased risk is unknown and requires further evaluation.


#3 Total And Segmental Body Composition Examination In Collegiate Football Players Using Multifrequency Bia And Dxa
Reference: J Strength Cond Res. 2017 Nov 6. doi: 10.1519/JSC.0000000000002320. [Epub ahead of print]
Authors: Raymond CJ, Dengel DR, Bosch TA
Summary: The current study examined the influence of player position on the agreement between multi-frequency bioelectrical impedance analysis (MfBIA) and dual X-ray absorptiometry (DXA) when assessing total and segmental percent body fat (BF%), fat mass (FM), and fat-free mass (FFM) in NCAA Division I collegiate football athletes. Forty-four male collegiate athletes (age=19±1 yrs; height=1.9±1.0 m; weight=106.4±18.8 kg) participated. Player positions included: offensive linemen (OL; n=7), tight ends (TE; n=4), wide receivers (WR; n=9), defensive linemen (DL; n=6), defensive backs (DB; n=8), linebackers (LB; n=6), and running backs (RB; n=4). Total and segmental body composition measured using MfBIA were compared with values obtained using DXA. Compared to DXA, MfBIA underestimated BF% (3.0±3.8%), total FM (2.5±4.3 kg), arm FM (0.4±0.8 kg), arm FFM (1.4±0.9 kg), leg FM (2.8±2.0 kg), and leg FFM (5.4±2.4 kg) (all p<0.001; arm FM p=0.002) and overestimated total FFM (-2.4±4.5 kg) (p<0.001). Limits of agreement (LOAs) were: ±7.39% (BF%), ±8.50 kg (total FM), ±1.50 kg (arm FM), ±1.83 kg (arm FFM), ±3.83 kg (leg FM), ±4.62 kg (leg FFM), and ±8.83 kg (total FFM). No significant differences were observed between devices for trunk FM (-0.3±3.0 kg; p = 0.565) and trunk FFM (0.4±2.4 kg; p=0.278), with LOAs of ±5.92 kg and ±4.69 kg, respectively. Player position significantly affected all between-device mean body composition measurement differences (adjusted p<0.05), with OL demonstrating the greatest effect on each variable. Therefore, MfBIA does not appear accurate in examining between-player body composition in college football players.


#4 Calling Injury Timeouts for the Medical Evaluation of Concussion: Determinants of Collegiate Football Officials' Behavior
Reference: J Athl Train. 2017 Nov 8. doi: 10.4085/1062-6050-52.11.XX. [Epub ahead of print]
Authors: Kroshus E, Parsons J, Hainline B
Summary: Sports officials can play an important role in concussion safety by calling injury timeouts so that athletic trainers can evaluate athletes with possible concussions. Understanding the determinants of whether officials call an injury timeout when they suspect a concussion has important implications for the design of interventions that better support officials in this role. The objective was to assess the knowledge of US collegiate football officials about concussion symptoms and to determine the associations between knowledge, perceived injunctive norms, and self-efficacy and calling injury timeouts for suspected concussions in athletes. Of the 3074 US collegiate football officials contacted, 1324 (43% response rate) participated. Concussion knowledge, injunctive norms (belief about what others would want them to do), and behavioral self-efficacy (confidence in their ability to call injury timeouts for suspected concussions in athletes during challenging game-day conditions) was used as outcome measures. Officials reported calling approximately 1 injury timeout for a suspected concussion every 4 games during the 2015 season. Structural equation modeling indicated that officials with more concussion-symptom knowledge had greater behavioral self-efficacy. Independent of an official's symptom knowledge, injunctive norms that were more supportive of calling an injury timeout were associated with greater self-efficacy. Concussion education for officials is important because when officials are aware of concussion symptoms, they are more confident in calling injury timeouts. Beyond increasing symptom knowledge, fostering sports environments that encourage concussion safety in all stakeholder groups can support officials in calling injury timeouts. Athletic trainers can help create sports environments that support proactive concussion identification by educating stakeholders, including officials, about the importance of concussion safety. When officials believe that other stakeholders support concussion safety, they are more likely to call injury timeouts if they suspect a concussion has occurred.


#5 Effects of Intravenous Cold Saline on Hyperthermic Athletes Representative of Large Football Players and Small Endurance Runners
Reference: Clin J Sport Med. 2017 Oct 27. doi: 10.1097/JSM.0000000000000505. [Epub ahead of print]
Authors: Morrison KE, Desai N, McGuigan C, Lennon M, Godek SF
Summary: The purpose was to evaluate the cooling effects of intravenous (IV) cold normal (0.9%) saline on hyperthermic athletes. Twelve male participants who were representative of a collegiate cross-country (6) and American football (6) population. Participants underwent body composition analysis using a BodPod. They were placed in an environmentally controlled chamber and brought to a Tc of 39.5°C with dynamic exercise. When temperatures were reached, they were treated with either 2 L of cold saline (CS) (4°C) or intravenous room temperature (22°C) saline (RS) over a ∼30-minute period. Tre was measured with a rectal temperature probe every minute during the treatment period. Total ΔTre (ending Tre - starting Tre) and cooling rate (total change in Tre/time) were measured for each condition, and body composition variables calculated included body surface area (BSA), BSA-to-mass ratio (BSA/mass), lean body mass, and body fat percentage (%BF) (P < 0.05). Statistically significant differences were found in the total ΔTre and cooling rate between the CS and RS trials. The cooling rate for the CS trials was significantly correlated to mass, BSA, BSA/mass, and %BF. In hyperthermic athletes, core temperature was reduced more effectively using chilled saline during IV infusion. Body composition had a significant impact on overall cooling revealing that the smaller and leaner participants cooled at a greater rate. When indicated, CS infusion could be considered for cooling hyperthermic individuals when other methods are not available.


#6 Meniscectomy and Resultant Articular Cartilage Lesions of the Knee Among Prospective National Football League Players: An Imaging and Performance Analysis
Reference: Am J Sports Med. 2017 Nov 1:363546517737991. doi: 10.1177/0363546517737991. [Epub ahead of print]
Authors: Chahla J, Cinque ME, Godin JA, Sanchez G, Lebus GF, Whalen JM, Price MD, Kennedy NI, Moatshe G, LaPrade RF, Provencher MT
Summary: The effect of prior meniscectomy and the resulting reduction in meniscal tissue on a potential National Football League (NFL) player's articular cartilage status and performance remain poorly elucidated. Purpose/Hypothesis: (1) To determine the epidemiology, imaging characteristics, and associated articular cartilage pathology of the knee among players with a previous meniscectomy who were participating in the NFL Combine and (2) to evaluate the effect of these injuries on performance as compared with matched controls. The hypothesis was that players with less meniscal tissue would have worse cartilage status and inferior performance metrics in their first 2 NFL seasons. All athletes with a history of a meniscectomy and magnetic resonance imaging scan of the knee who participated in the NFL Combine (2009-2015) were identified. Medical records and imaging were analyzed, and surgical history, games missed in college, position played, and draft position were documented. The conditions of the meniscus and cartilage were graded with modified ISAKOS scores (International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine) and ICRS scores (International Cartilage Repair Society), respectively. Players with a previous meniscectomy of at least 10% of total medial or lateral meniscal volume excised (ISAKOS meniscus grade ≤8) and matched controls without a significant pre-Combine injury were similarly evaluated and compared by position of play through analysis of draft position, number of games played and started, and how many eligible plays they participated in (snap percentage) within the first 2 NFL seasons. Of the 2285 players who participated in the NFL Combine (2009-2015), 287 players (322 knees) had a prior meniscectomy (206 lateral, 81 medial). Among these players, 247 (85%) had a total of 249 chondral lesions, most commonly on the lateral femoral condyle (111 lesions, 45%). There was a significant inverse correlation found between the ISAKOS medial and lateral meniscus grade and the corresponding compartment chondral lesion grade ( P = .001). A poorer meniscus score was also associated with worse chondral pathology, especially in the lateral compartment. After controlling for position of play, the injury-free control group had a significantly greater number of total games played and games started and higher snap percentage versus those with a prior meniscectomy of at least 10% volume (ISAKOS meniscus grade ≤8). Players with severe chondral lesions (ICRS grade 4) in the medial and lateral compartments had significantly worse performance metrics when compared with matched controls. Previous meniscectomy of at least 10% of total medial or lateral meniscus volume in prospective NFL players was significantly correlated with larger and more severe chondral lesions. Chondral and meniscal defects of the knee were found to result in a significant decrease in objective performance measures during a player's initial NFL career versus matched controls. Given these findings, players with a prior meniscectomy with evidence of chondral damage should be evaluated carefully for their overall functional levels; however, additional work is needed to fully clarify the effect of prior knee meniscal surgery on overall NFL performance.


#7 CranioSacral Therapy, Brain Injury, and American Football: Time for a Convergence
Reference: J Altern Complement Med. 2017 Nov 7. doi: 10.1089/acm.2017.0264. [Epub ahead of print]
Authors: Leskowitz E


#8 Correction to: Impact Performance of Modern Football Helmets
Reference: Ann Biomed Eng. 2017 Oct 25. doi: 10.1007/s10439-017-1948-8. [Epub ahead of print]
Authors: Viano DC, Withnall C, Halstead D
Summary: This erratum is to correct headings listing the impact location and speed in Figs. 5 and 6. The following provides corrected Figs. 5 and 6. The data is unchanged. The authors apologize for any inconvenience this might have caused.


#9 Clinical and Radiologic Outcomes After Scaphoid Fracture: Injury and Treatment Patterns in National Football League Combine Athletes Between 2009 and 2014
Reference: Arthroscopy. 2017 Nov 1. pii: S0749-8063(17)31071-X. doi: 10.1016/j.arthro.2017.08.259. [Epub ahead of print]
Authors: Moatshe G, Godin JA, Chahla J, Cinque ME, Kennedy NI, Sanchez G, Beaulieu-Jones BR, LaPrade RF, Provencher MT
Summary: The purpose was to report on the clinical and radiologic outcomes and complications after surgical treatment in National Football League (NFL) Combine athletes with a history of a scaphoid fracture. The medical records of 2,285 athletes participating in the NFL Combine from 2009 to 2015 were evaluated for a history of scaphoid, hand, or wrist injury. Clinical outcomes, including grip strength, pinch test, range of motion, and presence of pain and stiffness, were recorded. Imaging studies were evaluated for the percentage of healing, fixation treatment type, hardware complications, radiographic deformity, and presence of osteoarthritis. Of the 2,285 athletes evaluated, 56 presented with a history of a scaphoid fracture. Most fractures were in the middle and proximal aspects of the scaphoid. Of the scaphoid fractures, 76% (43 players) were treated with screw fixation. Of the athletes, 36 (72%) had normal range of motion of the affected wrist, 52 (93%) reported no pain, and 44 (83%) reported no stiffness in the affected wrist. The grip strength and pinch strength were 91% and 96%, respectively, of the uninjured side. The fracture was healed in 75% of the cases; however, 34% had degenerative changes. Hardware complications were found in 15% of the athletes. Good clinical outcomes can be achieved after scaphoid fractures in prospective NFL athletes. However, the rates of nonunion (25%), degenerative changes (34%), and hardware complications (15%) in this study suggest the need for close postoperative radiographic follow-up in this population of patients because their athletic demands may lead to higher rates of the aforementioned complications.



Australian Football
#1 Weak Relationships between Stint Duration, Physical and Skilled Match Performance in Australian Football
Reference: Front Physiol. 2017 Oct 23;8:820. doi: 10.3389/fphys.2017.00820. eCollection 2017.
Authors: Corbett DM, Sweeting AJ, Robertson S
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5660114/pdf/fphys-08-00820.pdf
Summary: Australian Rules football comprises physical and skilled performance for more than 90 min of play. The cognitive and physiological fatigue experienced by participants during a match may reduce performance. Consequently, the length of time an athlete is on the field before being interchanged (known as a stint), is a key tactic which could maximize the skill and physical output of the Australian Rules athlete. This study developed two methods to quantify the relationship between athlete time on field, skilled and physical output. Professional male athletes (n = 39) from a single elite Australian Rules football club participated, with physical output quantified via player tracking systems across 22 competitive matches. Skilled output was calculated as the sum of involvements performed by each athlete, collected from a commercial statistics company. A random intercept and slope model was built to identify how a team and individuals respond to physical outputs and stint lengths. Stint duration (mins), high intensity running (speeds >14.4 km · hr-1) per minute, meterage per minute and very high intensity running (speeds >25 km·hr-1) per minute had some relationship with skilled involvements. However, none of these relationships were strong, and the direction of influence for each player was varied. Three conditional inference trees were computed to identify the extent to which combinations of physical parameters altered the anticipated skilled output of players. Meterage per minute, player, round number and duration were all related to player involvement. All methods had an average error of 10 to 11 involvements, per player per match. Therefore, other factors aside from physical parameters extracted from wearable technologies may be needed to explain skilled output within Australian Rules football matches.


Gaelic Football
#1 The Influence Of Team Rating On Running Performance In Elite Gaelic Football
Reference: J Strength Cond Res. 2017 Nov 6. doi: 10.1519/JSC.0000000000002316. [Epub ahead of print]
Authors: Mangan S, Malone S, Ryan M, Gahan JM, Warne J, Martin D, O'Neill C, Burns C, Collins K.
Summary: It is currently unknown how team rating influences running performance in Gaelic football. GPS technologies were used to quantify match-running performance within 5 elite Gaelic football teams over a period of 5 years (2012-2016). In total 780 player data sets were collected over 95 matches. Running performance variables included total distance, high-speed distance (≥17 km h) and the percentage of high-speed distance. Team ratings were determined objectively using the Elo Ratings System for Gaelic football. Reference team rating had trivial effects on total distance (p = 0.011, partial η2 = 0.008) and high-speed distance (p = 0.011, partial η2 = 0.008). Opposition team rating had small effects on total distance (p = 0.005, partial η2 = 0.016) and high-speed distance (p = 0.001, partial η2 = 0.020). Top tier teams cover greater total distances and high-speed distance than lower tier teams. Players cover considerably less total distance and high-speed distance against tier 3 and tier 4 teams. Tier 1 players ran a significantly higher percentage of distance at high-speed, than players who played for tier 2 teams (p = 0.020). The competitive advantage of top tier Gaelic football teams is closely linked with their ability to demonstrate a higher physical intensity than lower tier teams.

Tue

21

Nov

2017

Football is...(#42)

Couple of reasons to monitor load

Fri

17

Nov

2017

Football is...(#41)

Individual injury history = possibility to tailor specific program

Wed

15

Nov

2017

Football is...(#40)

Recovery runs in training = improvement in defensive positioning

Wed

15

Nov

2017

Latest research in football - week 45 - 2017

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 Prospective evaluation of injuries occurred during a professional soccer championship in 206 in Sao Paulo
Reference: BrazilActa Ortop Bras. 2017 Sep-Oct;25(5):212-215. doi: 10.1590/1413-785220172505167238.
Authors: Arliani GG, Lara PHS, Astur DC, Pedrinelli A, Pagura JR, Cohen M
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5608742/pdf/1413-7852-aob-25-05-00212.pdf
Summary: The aim of the study was to identify the incidence of injuries, their main characteristics, and the way they were managed throughout 2016 in two major series of a professional soccer championship in São Paulo, Brazil. This prospective study used an electronic questionnaire previously developed by the Medical Committee of the Paulista Soccer Federation which was sent to the team doctors after each match. Two hundred and fifty-nine injuries occurred during 361 matches, and the incidence of injury per 1000 hours of game play was 21.32. Strikers were the most affected by injury; the most frequent diagnosis was muscle injury and the legs were predominantly affected. Most of the injuries occurred in the last 15 minutes of the first half and only 7.7% required surgical treatment. Muscle injuries were the most frequent, with most occurring in forwards and in the legs. Approximately half of the injuries occurred after contact and the vast majority was treated without surgery. MRI was the most requested exam and most injuries were classified as moderate (8 to 28 lost play days).


#2 Does decrease in hip range of motion interfere in frontal plane leg alignment in teenage soccer players?
Reference: Eur J Orthop Surg Traumatol. 2017 Oct 27. doi: 10.1007/s00590-017-2066-x. [Epub ahead of print]
Authors: Scaramussa K, de Castro JV, Ellera Gomes JL
Summary: This study determines cross-sectional changes in transverse plane hip range of motion (ROM) in teenager soccer athletes and non-athletes and correlates these measures with changes in frontal plane leg alignment (varus-valgus alignment). Participants were recruited from a major professional soccer club and two local state-run schools in southern Brazil. A total of 396 male participants aged 9-18 years were assessed, 183 soccer players (athlete group; mean age, 13.3 ± 2.7 years) and 213 students (non-athlete group; mean age 14.4 ± 2.5 years). Hip internal rotation (IR) and external rotation (ER) and frontal plane leg alignment were measured in all participants. Changes in transverse plane hip ROM and frontal plane leg alignment were determined. Mean IR was 20.7° ± 5.8° in athletes versus 32.8° ± 2.9° in non-athletes, and mean ER was 36.5° ± 7.4° in athletes versus 46.7° ± 4.8° in non-athletes. Overall, IR was decreased in the athlete group compared to the non-athlete group (P < 0.001). Mean IR and ER were significantly lower in older athletes (P < 0.001), while only ER was significantly lower in older non-athletes (P < 0.001). Varus leg alignment was prevalent at all ages in the athlete group (71.0%, P = 0.153). In the non-athlete group, the occurrence of varus leg alignment was higher in older participants (P = 0.001). Lower mean IR was correlated with more severe varus leg alignment in the athlete group (rs = 0.19; P = 0.009). We found a lower hip ROM, particularly in IR, in teenager soccer players according to the enhancement age group from the sample. But varus alignment of the leg was also prevalent in this group and comes before hip abnormalities started to be detected.


#3 Examination of the external and internal load indicators' association with overuse injuries in professional soccer players
Reference: J Sci Med Sport. 2017 Oct 13. pii: S1440-2440(17)31655-9. doi: 10.1016/j.jsams.2017.10.005. [Epub ahead of print]
Authors: Jaspers A, Kuyvenhoven JP, Staes F, Frencken WGP, Helsen WF, Brink MS
Summary: Research in professional soccer focusing on the relevance of external and internal load indicators for injury prevention is scarce. This study examined the relationship between load indicators and overuse injuries. Data were collected from 35 professional male soccer players over two seasons. Following load indicators were examined: total distance covered (TD), distance covered at high speed (THSR; >20kmh-1), number of accelerations (ACCeff; >1ms-2), number of decelerations (DECeff; <-1ms-2), and rating of perceived exertion (RPE) multiplied by duration. Cumulative 1-, 2-, 3-, 4-weekly loads and acute:chronic workload ratios (ACWR) were calculated and split into low, medium and high groups. Only overuse injuries were included in the analysis to focus on their specific relationship with the load indicators. Generalized estimating equations were applied to analyse the relationship between load indicators and overuse injuries in the subsequent week. In total, 64 overuse injuries were registered. For cumulative loads, results indicated an increased injury risk for higher 2- to 4-weekly loads as indicated by TD, DECeff, and RPE multiplied by duration. For ACWR, a high ratio for THSR (>1.18) resulted in a higher injury risk. In contrast, a lower injury risk was found when comparing medium ratios for ACCeff (0.87-1.12), DECeff (0.86-1.12), and RPE x duration (0.85-1.12) to low ratios. Findings demonstrate that mainly external load indicators are associated with increased or decreased injury risk. The monitoring of various load indicators is recommended for injury prevention in professional soccer.


#4 Individualisation of speed thresholds does not enhance the dose-response determination in football training
Reference: J Sports Sci. 2017 Nov 3:1-10. doi: 10.1080/02640414.2017.1398894. [Epub ahead of print]
Authors: Scott D, Lovell R
Summary: This study examined the utility of a range of approaches used to develop player-dependent speed zones in time-motion analysis (TMA), in determining the dose-response (internal load) of daily football training. Daily external (10 Hz GPS) and internal load (heart rate metrics, ratings of perceived exertion [RPE], wellness ratings) measures were tracked for 22 International women's football players during a 21-day training camp. High-speed (HSR) and very high speed running (VHSR) were determined according to arbitrary speed thresholds, as well as using a range of different individualization approaches that included the velocities corresponding to the heart rate deflection point, maximal aerobic speed, YYIR1 performance, and maximal sprint speed (MSS). Within-player correlations between the TMA approaches versus internal load measures quantified the dose-response to training. Correlations between HSR and VHSR vs. RPE were large (r = 0.53-0.67), with the exception of VHSR for the MSS technique (moderate; r = 0.44). HSR was very-largely associated with heart rate indices (r = 0.72-0.78), again with the exception of MSS (large; r = 0.60-0.67). Using a range of different fitness characteristics to individualise speed thresholds did not enhance the dose-response determination to daily fluctuations in external load, and was worsened with MSS per se.


#5 Comprehensive profile of hip, knee and ankle ranges of motion in professional football players
Reference: J Sports Med Phys Fitness. 2017 Oct 31. doi: 10.23736/S0022-4707.17.07910-5. [Epub ahead of print]
Authors: Lopez-Valenciano A, Ayala F, Vera-Garcia FJ, de Ste Croix M, Hernández-Sanchez S, Ruiz-Perez I, Cejudo A, Santonja F
Summary: Limited ranges of motion (ROM) have been considered as a primary risk factor for some football injuries, but only a few studies have analysed differences in lower extremity joints. The main purposes were (a) to describe the lower extremity ROM profile in professional football players; and (b) to examine differences between goalkeepers and outfield players. 82 professional male football players from 4 teams were measured in the 2013 pre-season. Measures of passive hip (flexion with knee flexed [PHFKF] and extended [PHFKE], extension [PHE], abduction [PHA], external [PHER] and internal [PHIR] rotation), knee (flexion [PKF]) and ankle (dorsiflexion with knee flexed [ADFKF] and extended [ADFKE]) ROMs were taken. Magnitude-based inferences exploring differences between player position and limb were made. 46% of all participants showed restricted PHFKE and/or around 30% showed restricted ADFKF ROM values. Contrarily, most players reported normal PHFKF, PHE, PHIR and PHER as well as PKF ROM scores with percentage values close to 100%. Bilateral meaningful differences for PHA, PHIR and PHER were found in approximately 30% of outfield players and goalkeepers. Statistical analysis found trivial differences between players for PHFKE, PHE, PHIR, PHER, ADFKE and ADFKF. However, moderate differences between players were found for PHFKF, PHA and PKF, with goalkeepers demonstrating higher values than outfield players. The findings of this study reinforce the necessity of prescribing exercises aimed at improving PHFKE and ADFKF ROM within everyday football training routines. In addition, as some bilateral deficits were observed, unilateral training should be considered where appropriate.


#6 An evaluation of the impact of FIFA World Cup on soccer emergency department injuries among Montreal adolescents
Reference: J Paediatr Child Health. 2017 Nov 10. doi: 10.1111/jpc.13784. [Epub ahead of print]
Authors: Keays G, Friedman D, Beaudin M, Gagnon I
Summary: The 'trickle-down effect', or how major sports events have a positive impact on sports participation, has been the subject of many studies, but none produced conclusive results. We took a different approach and rather than look at sports participation, we used injuries as a proxy and see if injuries increased, or remained the same, after the International Federation of Association Football World Cup. Using a retrospective cohort design, we looked at the injuries suffered by males and females (13-16 years old) while playing team sports in Montreal, that occurred in May to July, from 1999 to 2014. Information reported by the Canadian Hospitals Injury Reporting Prevention Program (CHIRPP) was limited to the two CHIRPP centres in Montreal: the Montreal Children's Hospital and Hopital Sainte-Justine. In females, no significant trends were noticed. In males who played non-organised soccer, the percent changes between FIFA World Cup (WC) (June) and pre-FIFA WC (May) was always highest during FIFA WC years: 17.2% more injuries in years when FIFA WC was held compared to 1.3% less injuries during non-FIFA WC years. In non-organised soccer, male players suffered less strains/sprains (11.9% vs. 30.1%; P = 0.015), suffered more severe injuries (59.7% vs. 43.1%; P = 0.049) and more of their injuries were the results of direct contact with another player (26.8% vs. 13.3%; P = 0.028) during FIFA WC. FIFA WC seems to have an impact on the injuries of teenage boys when playing non-organised soccer. The impact was short-lived, only lasting during the FIFA WC event.


#7 A soccer player with an unstable knee
Reference: Ned Tijdschr Geneeskd. 2017;161(0):D1524. [Article in Dutch]
Authors: Janssen D, Koc B, Jansen E
Summary: A 19-year-old soccer player presented with instability of his left knee after a rotation trauma. Congenital absence of the anterior cruciate ligament was suspected because of leg length discrepancy and specific MRI findings. He regained stability after an anterior cruciate reconstruction.


#8 An audit of injuries in six english professional soccer academies
Reference: J Sports Sci. 2017 Nov 10:1-7. doi: 10.1080/02640414.2017.1402535. [Epub ahead of print]
Authors: Read PJ, Oliver JL, De Ste Croix MBA, Myer GD, Lloyd RS
Summary: Regulations now state that professional academies in the United Kingdom are required to substantially increase the volume of soccer training. This study assessed the current injury occurrence, providing an update to reports published prior to the introduction of the Elite Player Performance Plan (EPPP). 608 soccer players aged 11-18 years from six professional soccer clubs were prospectively monitored, recording injuries during the 2014-2015 season. An injury rate of 1.32 injuries per player/season was indicated with a mean time loss of 21.9 days per injury. The greatest time loss per injury was in the U14s-U15s, and the highest rate of severe injuries in the U15s. Strains and sprains were the most common injury type, with the knee and ankle the most frequently injured anatomical sites. Seasonal variation indicated two peaks in injury incidence, occurring in September and January. In comparison to a published audit prior to the inception of the EPPP, this study indicates that academy soccer players are three-times more likely to experience an injury. Given that time loss and injury severity also increased during periods that typically follow rapid growth, these players should be considered an important group for training load monitoring and injury prevention strategies.


#9 Match-derived relative pitch area changes the physical and team tactical performance of elite soccer players in small-sided soccer games
Reference: J Sports Sci. 2017 Nov 10:1-7. doi: 10.1080/02640414.2017.1403412. [Epub ahead of print]
Authors: Olthof SBH, Frencken WGP, Lemmink KAPM
Summary: Small-sided games (SSGs) are used in training sessions to prepare for full-sized matches. For the same number of players, smaller pitch sizes result in decreased physical performance and shorter interpersonal distances. A relative pitch area derived from the full-sized match results in larger pitch sizes and this may increase the fit between SSGs and full-sized matches. This study aimed to investigate SSGs with a traditional small pitch and a match-derived relative pitch area in youth elite soccer players. Four age categories (under-13, under-15, under-17 and under-19) played 4 vs. 4 plus goalkeepers on a small (40x30m, 120m2 relative pitch area) and large pitch (68x47m, 320m2 relative pitch area). The number of games per age category ranged 15-30. Positional data (LPM-system) were collected to determine physical (total distance covered, high intensity distance and number of sprints) and team tactical (inter-team distance, LPW-ratio, surface area, stretch indices, goalkeeper-defender distance) performance measures and tactical variability. On a large pitch, physical performance significantly increased, inter-team and intra-team distances were significantly larger and tactical variability of intra-team distance measures significantly increased. The match-derived relative pitch area is an important training manipulation and leads to changes in physical and tactical performance 4 vs. 4 plus goalkeepers.


#10 Etiology and Recovery of Neuromuscular Fatigue following Competitive Soccer Match-Play
Reference: Front Physiol. 2017 Oct 25;8:831. doi: 10.3389/fphys.2017.00831. eCollection 2017.
Authors: Brownstein CG, Dent JP, Parker P, Hicks KM, Howatson G, Goodall S, Thomas K
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5661001/pdf/fphys-08-00831.pdf
Summary: Previous research into the etiology of neuromuscular fatigue following competitive soccer match-play has primarily focused on peripheral perturbations, with limited research assessing central nervous system function in the days post-match. The aim of the present study was to examine the contribution and time-course of recovery of central and peripheral factors toward neuromuscular fatigue following competitive soccer match-play. Sixteen male semi-professional soccer players completed a 90-min soccer match. Pre-, post- and at 24, 48, and 72 h participants completed a battery of neuromuscular, physical, and perceptual tests. Maximal voluntary contraction force (MVC) and twitch responses to electrical (femoral nerve) and transcranial magnetic stimulation (TMS) of the motor cortex during isometric knee-extension and at rest were measured to assess central nervous system (voluntary activation, VA) and muscle contractile (potentiated twitch force, Qtw, pot) function. Electromyography responses of the rectus femoris to single- and paired-pulse TMS were used to assess corticospinal excitability and short-interval intracortical inhibition (SICI), respectively. Fatigue and perceptions of muscle soreness were assessed via visual analog scales, and physical function was assessed through measures of jump (countermovement jump height and reactive strength index) and sprint performance. Competitive match-play elicited significant post-match declines in MVC force (-14%, P < 0.001) that persisted for 48 h (-4%, P = 0.01), before recovering by 72 h post-exercise. VA (motor point stimulation) was reduced immediately post-match (-8%, P < 0.001), and remained depressed at 24 h (-5%, P = 0.01) before recovering by 48 h post-exercise. Qtw,pot was reduced post-match (-14%, P < 0.001), remained depressed at 24 h (-6%, P = 0.01), before recovering by 48 h post-exercise. No changes were evident in corticospinal excitability or SICI. Jump performance took 48 h to recover, while perceptions of fatigue persisted at 72 h. Conclusion: Competitive soccer match-play elicits substantial impairments in central nervous system and muscle function, requiring up to 48 h to resolve. The results of the study could have important implications for fixture scheduling, the optimal management of the training process, squad rotation during congested competitive schedules, and the implementation of appropriate recovery interventions.



American Football
#1 Effects of Career Duration, Concussion History, and Playing Position on White Matter Microstructure and Functional Neural Recruitment in Former College and Professional Football Athletes
Reference: Radiology. 2017 Oct 31:170539. doi: 10.1148/radiol.2017170539. [Epub ahead of print]
Authors: Clark MD, Varangis EML, Champagne AA, Giovanello KS, Shi F, Kerr ZY, Smith JK, Guskiewicz KM
Summary: The purpose was to better understand the relationship between exposure to concussive and subconcussive head impacts, white matter integrity, and functional task-related neural activity in former U.S. football athletes. Materials and Methods Between 2011 and 2013, 61 cognitively unimpaired former collegiate and professional football players (age range, 52-65 years) provided informed consent to participate in this cross-sectional study. Participants were stratified across three crossed factors: career duration, concussion history, and primary playing position. Fractional anisotropy (FA) and blood oxygen level-dependent (BOLD) percent signal change (PSC) were measured with diffusion-weighted and task-related functional magnetic resonance imaging, respectively. Analyses of variance of FA and BOLD PSC were used to determine main or interaction effects of the three factors. Results A significant interaction between career duration and concussion history was observed; former college players with more than three concussions had lower FA in a broadly distributed area of white matter compared with those with zero to one concussion (t29 = 2.774; adjusted P = .037), and the opposite was observed for former professional players (t29 = 3.883; adjusted P = .001). A separate interaction between concussion history and position was observed: Nonspeed players with more than three concussions had lower FA in frontal white matter compared with those with zero to one concussion (t25 = 3.861; adjusted P = .002). Analysis of working memory-task BOLD PSC revealed a similar interaction between concussion history and position (all adjusted P < .004). Overall, former players with lower FA tended to have lower BOLD PSC across three levels of a working memory task. Conclusion Career duration and primary playing position seem to modify the effects of concussion history on white matter structure and neural recruitment. The differences in brain structure and function were observed in the absence of clinical impairment, which suggested that multimodal imaging may provide early markers of onset of traumatic neurodegenerative disease. © RSNA, 2017 Online supplemental material is available for this article.


#2 White matter alterations over the course of two consecutive high-school football seasons and the effect of a jugular compression collar: A preliminary longitudinal diffusion tensor imaging study
Reference: Hum Brain Mapp. 2017 Oct 28. doi: 10.1002/hbm.23859. [Epub ahead of print]
Authors: Yuan W, Barber Foss KD, Thomas S, DiCesare CA, Dudley JA, Kitchen K, Gadd B, Leach JL, Smith D, Altaye M, Gubanich P, Galloway RT, McCrory P, Bailes JE, Mannix R, Meehan WP 3rd, Myer GD
Summary: The cumulative effects of repetitive subclinical head impacts during sports may result in chronic white matter (WM) changes and possibly, neurodegenerative sequelae. In this pilot study, we investigated the longitudinal WM changes over the course of two consecutive high-school football seasons and explored the long-term effects of a jugular vein compression collar on these WM alterations. Diffusion tensor imaging data were prospectively collected both pre- and postseason in the two consecutive seasons. Participants were assigned into either collar or noncollar groups. Tract-based spatial statistics (TBSS) approach and region of interest-based approach were used to quantify changes in WM diffusion properties. Despite comparable exposure to repetitive head impacts, significant reductions in mean, axial, and/or radial diffusivity were identified in Season 1 in multiple WM regions in the noncollar group but not in the collar group. After an 8- to 9-month long off-season, these changes observed in the noncollar group partially and significantly reversed but also remained significantly different from the baseline. In Season 2, trend level WM alterations in the noncollar group were found but located in spatially different regions than Season 1. Last, the WM integrity in the collar group remained unchanged throughout the four time points. In conclusion, we quantitatively assessed the WM structural changes and partial reversal over the course of two consecutive high-school football seasons. In addition, the mitigated WM alterations in athletes in the collar group might indicate potential effect of the collar in ameliorating the changes against repetitive head impacts.


#3 Postural Control and Head Impact Exposure in Youth Football Players: Comparison of the Balance Error Scoring System and a Force Plate Protocol
Reference: J Appl Biomech. 2017 Nov 1:1-25. doi: 10.1123/jab.2017-0066. [Epub ahead of print]
Authors: Campolettano ET, Brolinson G, Rowson S
Summary: Postural control testing is often used by clinicians and athletic trainers to assess the health of athletes during recovery from a concussion. Characterization of postural control as a clinical tool for use with youth athletes is limited though. The objective of this study was to compare performance on the Balance Error Scoring System (BESS) and a force plate protocol at the beginning and end of a season of football within a cohort of 34 healthy youth football players (average age of 9.9 ± 0.6 years). A secondary aim was to investigate if changes in measures of balance from the postseason to the preseason were correlated with head impact exposure. Players completed testing at the beginning and end of the youth football season. There were no significant differences between BESS scores before the season and after the season (p = 0.54). Performance on the BESS was not associated with any of the center of pressure (COP) metrics considered in this study. No correlation was observed between measures of balance and head impact exposure for the season. Further research is required to determine the viability of postural control testing with this population.



Australian Football
#1 Brief Education Intervention Increases Nutrition Knowledge and Confidence of Coaches of Junior Australian Football Teams
Reference: Int J Sport Nutr Exerc Metab. 2017 Nov 1:1-21. doi: 10.1123/ijsnem.2017-0170. [Epub ahead of print]
Authors: Belski R, Donaldson A, Staley K, Skiadopoulos A, Randle E, O'Halloran P, Kappelides P, Teakel S, Stanley S, Nicholson M
Summary: This study evaluated the impact of a brief (20-minute) nutrition education intervention embedded in an existing mandatory coach education course for coaches of junior (8-12 year old) Australian football teams. Two hundred and eighty-four coaches (68% of 415 coaching course participants) completed a pre-session questionnaire and 110 (27% of coaching course participants) completed an identical post-session questionnaire. The responses to the pre- and post-session surveys were matched for 78 coaches. Coaches' ratings of their own understanding of the nutritional needs of young athletes (6.81, 8.95, p<0.001), the importance of young athletes adhering to a healthy diet (9.09, 9.67, p=001), their confidence in their own nutrition knowledge (7.24, 8.64, p<0.001) and their confidence in advising young athletes on nutrition and hydration practices (6.85, 8.62, p<0.001), all improved significantly following the education session. Nearly all coaches (>95%) provided a correct response to six of the 15 nutrition and hydration knowledge questions included in the pre-session questionnaire. Even with this high level of pre-session knowledge, there was a significant improvement in the coaches' nutrition and hydration knowledge after the education session across five of the 15 items, compared to before the education session. The results of this study suggest that a simple, short nutrition education intervention, embedded in an existing coach education course, can positively influence the nutrition knowledge and self-efficacy of community-level, volunteer coaches of junior sports participants.

Tue

14

Nov

2017

Football is...(#39)

Repeated sprint work to rest ratio of 1:6 = match demands

 

Mon

13

Nov

2017

Football is...(#38)

SSG with small player numbers = training offensive actions

Fri

10

Nov

2017

Football is...(#37)

Benefits utilizing split blocks with SSG.

Mon

06

Nov

2017

Latest research in football - week 44 - 2017

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 Acute and Residual Soccer Match-Related Fatigue: A Systematic Review and Meta-analysis
Reference: Sports Med. 2017 Nov 2. doi: 10.1007/s40279-017-0798-8. [Epub ahead of print]
Authors: Silva JR, Rumpf MC, Hertzog M, Castagna C, Farooq A, Girard O, Hader K

Full-test read: https://link.springer.com/epdf/10.1007/s40279-017-0798-8?author_access_token=zbISRhwR-ZwDDBJWZlZU2ve4RwlQNchNByi7wbcMAY6y_aUGySQg-494DXIFKoAvCj28IZ0ACKLvu-zVIZ24ZvxHDXDQPWW5XYROP3K5FxHmshJUT8sivfZ9eIVXRiV7RKW_u49GjOmZWnm-Wy6ung%3D%3D
Summary: Understanding soccer players' match-related fatigue and recovery profiles likely helps with developing conditioning programs that increase team performance and reduce injuries and illnesses. In order to improve match recovery (the return-to-play process and ergogenic interventions) it is also pivotal to determine if match simulation protocols and actual match-play lead to similar responses. The objectives were (1) To thoroughly describe the development of fatigue during actual soccer match play and its recovery time course in terms of physiological, neuromuscular, technical, biochemical and perceptual responses, and (2) to determine similarities of recovery responses between actual competition (11 vs. 11) and match simulations. A first screening phase consisted of a systematic search on PubMed (MEDLINE) and SportDiscus databases until March 2016. Inclusion criteria were: longitudinal study with soccer players; match or validated protocol; duration > 45 min; and published in English. A total of 77 eligible studies (n = 1105) were used to compute 1196 effect sizes (ES). Half-time assessments revealed small to large alterations in immunological parameters (e.g. leukocytes, ES = 1.9), a moderate decrement in insulin concentration (ES = - 0.9) and a small to moderate impairment in lower-limb muscle function (ES = - 0.5 to - 0.7) and physical performance measures (e.g. linear sprint, ES = - 0.3 to - 1.0). All the systematically analyzed fatigue-related markers were substantially altered at post-match. Hamstrings force production capacity (ES = - 0.7), physical performance (2-4%, ES = 0.3-0.5), creatine kinase (CK, ES = 0.4), well-being (ES = 0.2-0.4) and delayed onset muscle soreness (DOMS, ES = 0.6-1.3) remained substantially impaired at G + 72 h. Compared to simulation protocols, 11 vs. 11 match format (CK, ES = 1.8) induced a greater magnitude of change in muscle damage (i.e. CK, ES = 1.8 vs. 0.7), inflammatory (IL-6, ES = 2.6 vs. 1.1) and immunological markers and DOMS (ES = 1.5 vs. 0.7) than simulation protocols at post-assessments. Neuromuscular performances at post-match did not differ between protocols. While some parameters are fully recovered (e.g. hormonal and technical), our systematic review shows that a period of 72 h post-match play is not long enough to completely restore homeostatic balance (e.g. muscle damage, physical and well-being status). The extent of the recovery period post-soccer game cannot consist of a 'one size fits all approach'. Additionally, the 'real match' (11 vs. 11 format) likely induces greater magnitudes of perceptual (DOMS) and biochemical alterations (e.g. muscle damage), while neuromuscular alterations were essentially similar. Overall, coaches must adjust the structure and content of the training sessions during the 72-h post-match intervention to effectively manage the training load within this time-frame.

#2 Head impact locations in US high school boys' and girls' soccer concussions, 2012/13-2015/16
Reference: J Neurotrauma. 2017 Nov 1. doi: 10.1089/neu.2017.5319. [Epub ahead of print]
Authors: Kerr Z, Campbell KR, Fraser MA, Currie DW, Pierpoint LA, Kamimski T, Mihalik J
Summary: This study describes concussions and concussion-related outcomes sustained by high school soccer players by head impact location, sex, and injury mechanism. Data were obtained for the 2012/13-2015/16 school years from the National High School Sports-Related Injury Surveillance System, High School RIO™. This Internet-based sports injury surveillance system captures data reported by athletic trainers from an annual average of 162 US high schools. Data were analyzed to describe circumstances of soccer concussion (e.g., symptomology, symptom resolution and return-to-play time) by impact location [i.e., front- (face included), back-, side-, and top-of-the-head] and sex. Most concussions were from front-of-the-head impacts (boys: 30.5%; girls: 34.0%). Overall, 4.1±2.2 and 4.6±2.3 symptoms were reported in boys and girls, respectively. In boys, symptom frequency was not associated with head impact location (P=0.66); an association was found in girls (p=0.02), with the highest symptom frequency reported in top-of-the-head impacts (5.4±2.2). Head impact location was not associated with symptom resolution time (boys P=0.21; girls P=0.19) or return-to-play time (boys P=0.18; girls P=0.07). Heading was associated with 28.0% and 26.5% of concussions in boys and girls, respectively. Most player-player contact concussions during heading occurred from side-of-the-head impacts (boys: 49.4%; girls: 43.2%); most heading-related ball contact concussions occurred from front-of-the-head (boys: 41.4%; girls: 42.6%) and top-of-the-head (boys: 34.5%; girls: 36.9%) impacts. Head impact location was generally independent of symptom resolution time, return-to-play time, and recurrence among high school soccer concussions. However, impact location may be associated with reported symptom frequency. Further, many of these clinical concussion descriptors were associated with sex.


#3 Acute Effects Of Active, Ballistic, Passive And Proprioceptive Neuromuscular Facilitation Streching On Sprint And Vertical Jump Performance In Trained Young Soccer Players
Reference: J Strength Cond Res. 2017 Oct 27. doi: 10.1519/JSC.0000000000002298. [Epub ahead of print]
Authors: de Paula Oliveira L, Palucci Vieira LH, Aquino R, Vieira Manechini JP, Pereira Santiago PR, Puggina EF.
Summary: The aim of the present study was to compare the acute effects of active (AC), ballistic (BA), passive (PA), proprioceptive neuromuscular facilitation stretching (PNF) methods on performance in vertical jumping, sit and reach, and sprinting in young soccer players. Twelve trained soccer players (17.67 ± 0.87 years) participated in the study. The jump height (H), peak power (PP), and relative power (RP) in the squat jump (SJ) and countermovement jump (CMJ), the range of motion (ROM), the rate of perceived exertion (RPE), and time (s) in 10-20-30 m sprints were evaluated. Significant differences (p <0.05) in H were found in the comparisons between the PA and control condition (CO) for the SJ. For the CMJ, differences in H were observed between the PA and CO, and PNF with CO and BA, and in the PP between the PNF and CO, AC, and BA, as well as in the RP between the PNF and BA. Significant increases in ROM were found in the AC, BA, PA, and PNF, compared to the CO. In relation to RPE, higher scores were reported in the PA and PNF conditions compared to the AC and BA. No significant differences were found in 10-20-30 m sprints. Therefore, the AC and BA methods can be used prior to vertical jump and sprint activities, with the aim of increasing flexibility. However, the PA and PNF methods should be avoided, due to subsequent negative effects on vertical jump performance.


#4 Fractures in German elite male soccer
Reference: J Sports Med Phys Fitness. 2017 Oct 27. doi: 10.23736/S0022-4707.17.07901-4. [Epub ahead of print]
Authors: Schiffner E, Latz D, Grassmann JP, Schek A, Scholz A, Windolf J, Jungbluth P, Schneppendahl J
Summary: Aim of this retrospective cohort study was to identify fracture epidemiology and off times after different types of fractures in German male elite soccer players from the first division Bundesliga based on information from the public media. Exposure and fracture data over 7.5 consecutive seasons (2009/10 -1.Half 2016/17) were collected from two media based register (transfermarkt.de® and kicker.de®). 357 fractures from 290 different players were recorded with an incidences of 0.19/1000 h of exposure (95% 0.14 - 0.24). Most fractures in German elite soccer players involved the lower extremities (35.3%), the head/face (30.3%) and the upper extremities (24.9%). The median off time after a fracture in German elite male professional soccer in 7.5 Season was 51.1 days (range 0-144). The number of fractures per 100 players per season decreased between 2009 and 2016. There was no significant difference in overall fracture incidence when comparing players at different position (p=0.11). Goalkeepers have a significantly (p<0.02) higher likelihood of suffering hand and finger fractures and they are significantly (p<0.03) less prone of suffering foot fractures, cranial and maxillofacial fractures (p<0.04) compared to outfield players. This study can confirm that male professional soccer teams experience 1-2 fractures per season in German elite soccer. The incidence of fractures in elite German soccer players decreased between 2009 and 2016. The most fractures occur in the lower extremities and there is no difference in overall fracture risk for players at different playing positions. The information from our study might be of a great importance to medical practitioners, soccer coaches and soccer manager.


#5 Exercise to rest ratios in RSA training in women's soccer
Reference: J Sports Med Phys Fitness. 2017 Oct 27. doi: 10.23736/S0022-4707.17.07741-6. [Epub ahead of print]
Authors: Ruscello B, Esposito M, Partipilo F, DI Cicco D, Filetti C, Pantanella L, D'Ottavio S
Summary: The purpose was to investigate the applicability of three different exercise to rest ratios in RSA training in women's soccer players, applying those ones already adopted in male adult and young players, when performing three different sprinting modes (straight, shuttle and sprinting with changing of direction). 15 trained female soccer players (height: 1.65 ± 0.06 m; weight: 59.3 ± 9.0 kg; BMI 21.6 ± 2.7 kg·m-2; age: 23.3±5.9 years) participated to the study. In order to compare the different values of the time recorded, an Index of Fatigue was used. Recovery times among trials in the sets were administered according to the 1:5, 1:3; 1:2 exercise to rest ratio, respectively. Blood lactate concentrations at the end of each set (3') were analyzed. Significant differences among trials within each set (Repeated Measures Anova; p<0.05) were found, as evidence of fatigue over time, with an average decay of performance of about 5% but no significant differences were found in IF%, among the three different sprinting modalities when applying the investigated exercise to rest ratios (Factorial Anova; between; p>0.05). Significant differences were found in blood lactate concentrations (p<0.05). The results of this study confirm that the exercise to rest ratios considered in this study might be suitable to design effective testing protocols and training sessions aimed at the development of the RSA in women's soccer players, keeping the performances in the speed domain (IF% < ⊕7-8%) but inducing the fatigue processes sought with this kind of training method.


#6 Influence of different types of compression garments on exercise-induced muscle damage markers after a soccer match
Reference: Res Sports Med. 2017 Oct 30:1-16. doi: 10.1080/15438627.2017.1393755. [Epub ahead of print]
Authors: Marques-Jimenez D, Calleja-Gonzalez J, Arratibel-Imaz I, Delextrat A, Uriarte F, Terrados N
Summary: There is not enough evidence of positive effects of compression therapy on the recovery of soccer players after matches. Therefore, the objective was to evaluate the influence of different types of compression garments in reducing exercise-induced muscle damage (EIMD) during recovery after a friendly soccer match. Eighteen semi-professional soccer players (24 ± 4.07 years, 177 ± 5 cm; 71.8 ± 6.28 kg and 22.73 ± 1.81 BMI) participated in this study. A two-stage crossover design was chosen. Participants acted as controls in one match and were assigned to an experimental group (compression stockings group, full-leg compression group, shorts group) in the other match. Participants in experimental groups played the match wearing the assigned compression garments, which were also worn in the 3 days post-match, for 7 h each day. Results showed a positive, but not significant, effect of compression garments on attenuating EIMD biomarkers response, and inflammatory and perceptual responses suggest that compression may improve physiological and psychological recovery.


#7 Tanner-Whitehouse Skeletal Ages in Male Youth Soccer Players: TW2 or TW3?
Reference: Sports Med. 2017 Oct 29. doi: 10.1007/s40279-017-0799-7. [Epub ahead of print]
Authors: Malina RM, Coelho-E-Silva MJ, Figueiredo AJ, Philippaerts RM, Hirose N, Pena Reyes ME, Gilli G, Benso A, Vaeyens R, Deprez D, Guglielmo LF, Buranarugsa R
Summary: The Tanner-Whitehouse radius-ulna-short bone protocol (TW2 RUS) for the assessment of skeletal age (SA) is widely used to estimate the biological (skeletal) maturity status of children and adolescents. The scale for converting TW RUS ratings to an SA has been revised (TW3 RUS) and has implications for studies of youth athletes in age-group sports. The aim of this study was to compare TW2 and TW3 RUS SAs in an international sample of male youth soccer players and to compare distributions of players by maturity status defined by each SA protocol. SA assessments with the TW RUS method were collated for 1831 male soccer players aged 11-17 years from eight countries. RUS scores were converted to TW2 and TW3 SAs using the appropriate tables. SAs were related to chronological age (CA) in individual athletes and compared by CA groups. The difference of SA minus CA with TW2 SA and with TW3 SA was used to classify players as late, average, or early maturing with each method. Concordance of maturity classifications was evaluated with Cohen's Kappa coefficients. For the same RUS score, TW3 SAs were systematically and substantially reduced compared with TW2 SAs; mean differences by CA group ranged from - 0.97 to - 1.16 years. Kappa coefficients indicated at best fair concordance of TW2 and TW3 maturity classifications. Across the age range, 42% of players classified as average with TW2 SA were classified as late with TW3 SA, and 64% of players classified as early with TW2 SA were classified as average with TW3 SA. TW3 SAs were systematically lower than corresponding TW2 SAs in male youth soccer players. The differences between scales have major implications for the classification of players by maturity status, which is central to some talent development programs.


#8 Orthopedic injuries in soccer – an analysis of professional championship tournament in Brazil
Reference:  Acta Ortop Bras. 2017 Sep-Oct;25(5):216-219. doi: 10.1590/1413-785220172505171247.
Authors: Souza RFR, Mainine S, Souza FFR, Zanon EM, Nishimi AY, Dobashi ET, Fernandes FA
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5608743/pdf/1413-7852-aob-25-05-00216.pdf
Summary: The purpose was to analyze the incidence of orthopedic injuries which occurred during a professional soccer championship in São Paulo, Brazil in 2010. This assessment collected data from the pre-season until the final stage of the championship. We analyzed 227 professional players from eight of the top teams in this championship. Data were obtained for 71.02% of all games. The athletes were all male with a mean age of 23.1 years; the average number of injuries was 1.6 per athlete, with muscle injuries and sprains resulting from indirect origin predominating in the legs. Injuries were more frequent in forwards and outside backs, and players generally returned to play within one week of treatment.

Fri

03

Nov

2017

Football is...(#36)

Throw-ins could = ball possession or goal scoring opportunity

Sun

29

Oct

2017

Latest research in football - week 43 - 2017

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 Is there a correlation between coaches' leadership styles and injuries in elite football teams? A study of 36 elite teams in 17 countries
Reference: Br J Sports Med. 2017 Oct 22. pii: bjsports-2017-098001. doi: 10.1136/bjsports-2017-098001. [Epub ahead of print]
Authors: Ekstrand J, Lundqvist D, Lagerback L, Vouillamoz M, Papadimitiou N, Karlsson J
Summary: Do coaches' leadership styles affect injury rates and the availability of players in professional football? Certain types of leadership behaviour may cause stress and have a negative impact on players' health and well-being. The aim of the study was to investigate the transformational leadership styles of head coaches in elite men's football and to evaluate the correlation between leadership styles, injury rates and players' availability. Medical staff from 36 elite football clubs in 17 European countries produced 77 reports at four postseason meetings with a view to assessing their perception of the type of leadership exhibited by the head coaches of their respective teams using the Global Transformational Leadership scale. At the same time, they also recorded details of individual players' exposure to football and time-loss injuries. There was a negative correlation between the overall level of transformational leadership and the incidence of severe injuries (rho=-0.248; n=77; p=0.030); high levels of transformational leadership were associated with smaller numbers of severe injuries. Global Transformational Leadership only explained 6% of variation in the incidence of severe injuries (r2=0.062). The incidence of severe injuries was lower at clubs where coaches communicated a clear and positive vision, supported staff members and gave players encouragement and recognition. Players' attendance rates at training were higher in teams where coaches gave encouragement and recognition to staff members, encouraged innovative thinking, fostered trust and cooperation and acted as role models. There is an association between injury rates and players' availability and the leadership style of the head coach.


#2 Sex and age differences in head acceleration during purposeful soccer heading
Reference: Res Sports Med. 2017 Oct 25:1-11. doi: 10.1080/15438627.2017.1393756. [Epub ahead of print]
Authors: Caccese JB, Buckley TA, Tierney RT, Rose WC, Glutting JJ, Kaminski TW
Summary: Differences in head-neck segment mass, purposeful heading technique, and cervical strength and stiffness may contribute to differences in head accelerations across sex and age. The purpose of this study was to compare head acceleration across sex and age (youth [12-14 years old], high school and collegiate) during purposeful soccer heading. One-hundred soccer players (42 male, 58 female, 17.1 ± 3.5 years, 168.5 ± 20.3 cm, 61.5 ± 13.7 kg) completed 12 controlled soccer headers at an initial ball velocity of 11.2 m/s. Linear and rotational accelerations were measured using a triaxial accelerometer and gyroscope and were transformed to the head centre-of-mass. A MANOVA revealed a significant multivariate main effect for sex (Pillai's Trace = .165, F(2,91) = 11.868, p < .001), but not for age (Pillai's Trace = .033, F(4,182) = 0.646, p = .630). Peak linear and rotational accelerations were higher in females (40.9 ± 13.3 g; 3279 ± 1065 rad/s2) than males (27.6 ± 8.5 g, 2219 ± 823 rad/s2). These data suggest that under controlled soccer heading conditions, females may be exposed to higher head accelerations than males.


#3 Multifactorial examination of sex-differences in head injuries and concussions among collegiate soccer players: NCAA ISS, 2004-2009
Reference: Inj Epidemiol. 2017 Oct 25;4(1):28. doi: 10.1186/s40621-017-0127-6.
Authors: Chandran A, Barron MJ, Westerman BJ, DiPietro L
Summary: While head injuries and concussions are major concerns among soccer players, the multifactorial nature of head injury observations in this group remains relatively undefined. We aim to extend previous analyses and examine sex-differences in the incidence of head injuries, odds of head injuries within an injured sample, and severity of head injuries, among collegiate soccer players between 2004 and 2009. Data collected within the National Collegiate Athletic Association (NCAA) Injury Surveillance System (ISS) between the years of 2004 and 2009, were analyzed in this study. Unadjusted rate ratios (RR), compared incidence rates between categories of sex, injury mechanism, setting and competition level. We also examined sex-differences in head injury incidence rates, across categories of the other covariates. Multivariable logistic regression and negative binomial regression modeling tested the relation between sex and head injury corollaries, while controlling for contact, setting, and competition level. Between 2004 and 2009, head injuries accounted for approximately 11% of all soccer-related injuries reported within the NCAA-ISS. The rate of head injuries among women was higher than among men (RR = 1.23, 95% CI = [1.08, 1.41]). The rate of head injuries due to player-to-player contact was comparable between women and men (RR = 0.95, 95% CI = [0.81, 1.11]). Whereas, the rate of injury due to contact with apparatus (ball/goal) was nearly 2.5 times higher (RR = 2.46, 95% CI = [1.76, 3.44]) and the rate due to contact with a playing surface was over two times higher (RR = 2.29, 95% CI = [1.34, 3.91]) in women than in men. In our multifactorial models, we also observed that the association between sex and head injury corollaries varied by injury mechanism. Sex-differences in the incidence, odds (given an injury), and severity (concussion diagnosis, time-loss) of head injuries varied by injury mechanism (player-to-player contact vs. all other mechanisms) in this sample.


#4 Leg Stiffness in Female Soccer Players: Intersession Reliability and the Fatiguing Effects of Soccer-Specific Exercise
Reference: J Strength Cond Res. 2017 Nov;31(11):3052-3058. doi: 10.1519/JSC.0000000000001715.
Authors: De Ste Croix MBA, Hughes JD, Lloyd RS, Oliver JL, Read PJ
Summary: Low levels of leg stiffness and reduced leg stiffness when fatigue is present compromise physical performance and increase injury risk. The purpose of this study was to (a) determine the reliability of leg stiffness measures obtained from contact mat data and (b) explore age-related differences in leg stiffness after exposure to a soccer-specific fatigue protocol in young female soccer players. Thirty-seven uninjured female youth soccer players divided into 3 subgroups based on chronological age (under 13 [U13], under 15 [U15], and under 17 [U17] year-olds) volunteered to participate in the study. After baseline data collection, during which relative leg stiffness, contact time, and flight time were collected, participants completed an age-appropriate soccer-specific fatigue protocol (SAFT). Upon completion of the fatigue protocol, subjects were immediately retested. Intersession reliability was acceptable and could be considered capable of detecting worthwhile changes in performance. Results showed that leg stiffness decreased in the U13 year-olds, was maintained in the U15 age group, and increased in the U17 players. Contact times and flight times did not change in the U13 and U15 year-olds, but significantly decreased and increased, respectively, in the U17 age group. The data suggest that age-related changes in the neuromuscular control of leg stiffness are present in youth female soccer players. Practitioners should be aware of these discrepancies in neuromuscular responses to soccer-specific fatigue, and should tailor training programs to meet the needs of individuals, which may subsequently enhance performance and reduce injury risk.


#5 Biomechanical Differences of Multidirectional Jump Landings Among Female Basketball and Soccer Players
Reference: J Strength Cond Res. 2017 Nov;31(11):3034-3045. doi: 10.1519/JSC.0000000000001785.
Authors: Taylor JB, Ford KR, Schmitz RJ, Ross SE, Ackerman TA, Shultz SJ
Summary: Anterior cruciate ligament (ACL) injury prevention programs are less successful in basketball than soccer and may be due to distinct movement strategies that these athletes develop from sport-specific training. The purpose of this study was to identify biomechanical differences between female basketball and soccer players during multidirectional jump landings. Lower extremity biomechanics of 89 female athletes who played competitive basketball (n = 40) or soccer (n = 49) at the middle- or high-school level were analyzed with 3-dimensional motion analysis during a drop vertical jump, double- (SAG-DL) and single-leg forward jump (SAG-SL), and double- (FRONT-DL) and single-leg (FRONT-SL) lateral jump. Basketball players landed with either less hip or knee, or both hip and knee excursion during all tasks (p ≤ 0.05) except for the SAGSL task, basketball players landed with greater peak hip flexion angles (p = 0.04). The FRONT-SL task elicited the most distinct sport-specific differences, including decreased hip adduction (p < 0.001) angles, increased hip internal rotation (p = 0.003), and increased relative knee external rotation (p = 0.001) excursions in basketball players. In addition, the FRONT-SL task elicited greater forces in knee abduction (p = 0.003) and lesser forces in hip adduction (p = 0.001) and knee external rotation (p < 0.001) in basketball players. Joint energetics were different during the FRONT-DL task, as basketball players exhibited less sagittal plane energy absorption at the hip (p < 0.001) and greater hip (p < 0.001) and knee (p = 0.001) joint stiffness. Sport-specific movement strategies were identified during all jump landing tasks, such that soccer players exhibited a more protective landing strategy than basketball players, justifying future efforts toward sport-specific ACL injury prevention programs.


#6 Head Impact Exposure in Youth Soccer and Variation by Age and Sex
Reference: Clin J Sport Med. 2017 Oct 20. doi: 10.1097/JSM.0000000000000497. [Epub ahead of print]
Authors: Chrisman SPD, Ebel BE, Stein E, Lowry SJ, Rivara FP
Summary: The purpose was to examine variation in head impact exposure (HIE) by age and sex in youth soccer. Youth soccer athletes (11-14 years old) in local clubs participated in this study.  Head impact exposure measured using adhesive-mounted accelerometers during 1 month of soccer. Forty-six youth athletes (54% female) participated. No athlete reported a concussion during the study. More males than females had at least 1 head impact ≥15 g (P = 0.02). Of those who sustained a head impact above the 15-g threshold (57%), females sustained HIE of greater magnitude than males (median 47.4 g vs 33.3 g, P = 0.04). Eighty-five percent of athletes on U14 teams had at least 1 head impact ≥15 g compared with 15% of athletes on U12 teams (P < 0.001). Poisson regression stratified by sex and controlling for team-suggested age effects were significant only for females (P = 0.02). There was significant variation in HIE by team. There were no decrements in concussion symptoms, health-related quality of life, or neuropsychological testing after 1 month of soccer play. There is significant variation in HIE in youth soccer, which seems to be influenced by age and sex. Further studies are needed to better understand potential significance for injury prevention.


#7 Combined visual and dribbling performance in young soccer players of different expertise
Reference: Res Sports Med. 2017 Oct 23:1-8. doi: 10.1080/15438627.2017.1393751. [Epub ahead of print]
Authors: Bekris E, Gissis I, Ispyrlidis I, Mylonis E, Axeti G
Summary: We aimed to evaluate dribbling performance in terms of technique and visual skills assessment of both young experienced (EX, n = 24) and novice (NO, n = 24) soccer players. Both groups performed two dribbling tests with four levels of difficulty in visual signals (A1-A4 and B1-B4; B - half distance of A; 1 - no visual signal; 4 - signal with the shorter flashing time). All players performed slower when visual signals were added to the testing process (~2.5 s; p < 0.01). EX completed all tests faster than NO (~3 s, p < 0.01). The average number of visual mistakes was significantly lower for EX than NO in all tests (p < 0.01). These results demonstrated the importance of evaluating dribbling along with visual stimuli in young soccer EX and NO players.


#8 Positional synchronization affects physical and physiological responses to preseason in professional football (soccer)
Reference: Res Sports Med. 2017 Oct 23:1-13. doi: 10.1080/15438627.2017.1393754. [Epub ahead of print]
Authors: Folgado H, Goncalves B, Sampaio J
Summary: This study aimed to identify changes in tactical, physical and physiological performances in large-sided games during the preseason of elite footballers. Thirty professional football players participated in several GK+8vs.8+GK large-sided games across the first four weeks of the season. Players were monitored by GPS units and heart rate monitors to quantify physical, physiological and tactical performances. The variables were compared according to the preseason period, players' positioning and professional experience. The training situation promoted similar physiological responses during the first and the last training period. However, players were revealed to have higher levels of positional synchronization during the last preseason period, indicating an improved tactical performance. Tactical variables seem to reflect the improvement of players' performance during the preseason, measured in large-sided games situation, while affecting both physical and physiological demands. These results highlight the potential of positioning derived variables, concurrently to physical and physiological variables, for football training optimization.


American Football
#1 Risk and Causes of Death among Former National Football League Players (1986-2012)
Reference: Med Sci Sports Exerc. 2017 Oct 26. doi: 10.1249/MSS.0000000000001466. [Epub ahead of print]
Authors: Lincoln AE, Vogel RA, Allen TW, Dunn RE, Alexander K, Kaufman ND, Tucker AM
Summary: Previous research identified decreased overall and cardiovascular mortality for National Football League (NFL) players from the 1959-1988 era. The present study explored the mortality risk among recent NFL players who played in an era of heavier linemen and nearly year-round physical conditioning. This cohort study included 9778 former NFL players with at least one year in the NFL whose last season was between 1986 and 2012. Players' pension fund records were matched to the National Death Index (NDI) to determine vital status, date of death, and cause of death. Standardized mortality ratios (SMRs) compared player mortality through 2014 with US men of the same age, race, and calendar year. Cox proportional hazards models assessed the effect of player characteristics on overall and cardiovascular mortality. Two percent (n=227) of players were deceased with a median age at death of 38 years (range: 23-61). The most common major causes of death were diseases of the heart (n=47, 21%), violence (n=39, 17%), and transportation injuries (n=34, 15%). Risk of death was significantly lower than the general population for overall mortality (SMR 0.46, 95% CI 0.40-0.52), cardiovascular disease (SMR 0.65, 95% CI 0.50-0.84), and other major causes. Players with playing-time BMI>35 kg/m had significantly higher cardiovascular disease mortality (SMR 2.20, 95% CI 1.32-3.44) than the general population and higher overall mortality risk (SRR 3.84, 95% CI 2.66-5.54) than players with BMI<30 kg/m. Consistent with an earlier NFL cohort and other elite athlete populations, the overall and cardiovascular mortality risk of this NFL cohort was significantly lower than the general US male population, likely attributable to a healthy worker effect and less smoking.However, players with the highest playing-time BMI exhibited elevated cardiovascular mortality risk.


#2 Acute changes in plasma total Tau levels are independent of subconcussive head impacts in college football players
Reference: J Neurotrauma. 2017 Oct 26. doi: 10.1089/neu.2017.5376. [Epub ahead of print]
Authors: Kawata K, Rubin LH, Wesley L, Lee J, Sim T, Takahagi M, Bellamy A, Tierney R, Langford D
Summary: Athletes in contact sports sustain repetitive subconcussive head impacts in a brief window, yet neurophysiological sequelae from repetitive subconcussion remain unclear. This prospective longitudinal study examined a relationship between changes in plasma Tau protein levels and subconcussive impact kinematic data in 23 Division-I collegiate football players during a series of pre-season practices. Plasma measures for Tau and S100β proteins, symptom scores, and near point of convergence were obtained at preseason baseline and pre-post practices. During each practice, impact frequency and linear and rotational head accelerations were recorded via an accelerometer-embedded mouth guard. There were significant elevations in plasma Tau levels at all post-practice time points compared to those of pre-practice and baseline levels. However, the highest degree of elevation in plasma Tau was observed after the first practice, for which players sustained the lowest number of hits and magnitudes for these hits. Subconcussive impact exposure during practice (e.g., head impact frequency and magnitude) did not predict increased plasma Tau levels. Concussion history and years of football experience were also unrelated to changes in plasma Tau levels. Increases in plasma Tau levels were associated with increases in S100β levels only after the first practice. There were no significant aassociations between changes in Tau levels, symptom scores, or near point of convergence. These data suggest that the changes in levels of circulating Tau protein were independent from subconcussive head impact exposure, pointing to the possibility that other factors may have played roles in changes in plasma Tau levels.


#3 Why Professional Football Players Chose Not to Reveal Their Concussion Symptoms During a Practice or Game
Reference: Clin J Sport Med. 2017 Oct 20. doi: 10.1097/JSM.0000000000000495. [Epub ahead of print]
Authors: Delaney JS, Caron JG, Correa JA, Bloom GA
Summary: The purpose was to determine why professional football players in Canada decided not to seek medical attention during a game or practice when they believed they had suffered a concussion. Four hundred fifty-four male professional football players participated in this study. Reasons athletes did not seek medical attention for a presumed concussion during the previous season, how often this occurred and how important these reasons were in the decision process were used as outcome measured. One hundred six of the 454 respondents (23.4%) believed they had suffered a concussion during their previous football season and 87 of the 106 (82.1%) did not seek medical attention for a concussion at least once during that season. The response "Did not feel the concussion was serious/severe and felt you could still continue to play with little danger to yourself" was the most commonly listed reason (49/106) for not seeking medical attention for a presumed concussion. Many players answered that they did not seek medical attention because they did not want to be removed from a game (42/106) and/or they did not want to risk missing future games (41/106) by being diagnosed with a concussion. Some professional football players who believed they had suffered a concussion chose not to seek medical attention at the time of injury. Players seemed educated about the concussion evaluation process and possible treatment guidelines, but this knowledge did not necessarily translate into safe and appropriate behavior at the time of injury.



Gaelic Football
#1 Lower limb injuries in men's elite Gaelic football: A prospective investigation among division one teams from 2008 to 2015
Reference: J Sci Med Sport. 2017 Sep 6. pii: S1440-2440(17)31028-9. doi: 10.1016/j.jsams.2017.08.023. [Epub ahead of print]
Authors: Roe M, Murphy JC, Gissane C, Blake C
Summary: The purpose was to prospectively investigate incidence and associated time-loss of lower limb injuries in elite Gaelic football. Additionally, to identify sub-groups of elite players at increased risk of sustaining a lower limb injury. Team physiotherapists provided exposure and injury on a weekly basis to the National Gaelic Athletic Association (GAA) Injury Surveillance Database. Injury was defined using a time-loss criterion. Fifteen different teams participated throughout the 8-year study providing 36 team datasets from 2008 to 2015. Lower limb injuries (n=1239) accounted for 83.5% (95% CI 82.0-85.0) and 77.6% (95% CI 75.8-79.4) of training and match-play injuries, respectively. Injury incidence was 4.5 (95% CI 3.7-5.2) and 38.4 (95% CI 34.3-42.60) per 1000 training and match-play hours, respectively. One-in-four (25.0%, 95% CI 22.4-27.0) lower limb injuries were recurrent. Non-contact injuries accounted for 80.9% (95% CI 79.2-82.6) of cases. The median team rate was 30 (IQR 24-43) lower limb injuries per season resulting in 840.8 (95% CI 773.3-908.2) time-loss days. Previously injured players had a 2.5-times (OR 95% CI 2.2-2.8) greater risk of sustaining a lower limb injury. Overall, 56.8% of players with a previous lower limb injury sustained another. Incidence was higher for forward players and those aged >25years. Lower limb injuries are the most common injury among elite division one Gaelic football teams. Injury risk management should become an ongoing component of a player's development programme and consider injury history, age, and playing position.

Sun

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2017

Football is...(#35)

Preparing the players with football specific movements.

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27

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2017

Football is...(#34)

Time motion analysis to design training sessions.

Mon

23

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2017

Latest research in football - week 42 - 2017

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 Repeated-Sprint Ability in Division I Collegiate Male Soccer Players: Positional Differences and Relationships with Performance Tests
Reference: J Strength Cond Res. 2017 Oct 16. doi: 10.1519/JSC.0000000000001948. [Epub ahead of print]
Autors: Lockie RG, Moreno MR, Orjalo AJ, Stage AA, Liu TM, Birmingham-Babauta SA, Hurley JM, Torne IA, Beiley MD, Risso FG, Davis DL, Lazar A, Stokes JJ, Giuliano DV.
Summary: Repeated-sprint ability (RSA) in essential for soccer. Important considerations when assessing RSA is whether there are differences between positions (defenders, midfielders, forwards), and what physiological characteristics may contribute to RSA. This has not been assessed in collegiate male players. Eighteen Division I male field players from one school performed several performance tests. The RSA test involved 7 x 30-m sprints completed on 20-s cycles. Measurements included total time (TT), and performance decrement (percent change in time from the first to last sprint; PD). Subjects also completed tests of lower-body power (vertical [VJ] and standing broad [SBJ] jump); linear (30-m sprint; 0-5, 0-10, 0-30 m intervals) and change-of-direction (505) speed; and soccer-specific endurance (Yo-Yo Intermittent Recovery Test Level 2; YYIRT2). A one-way ANOVA (p < 0.05) determined between-position differences, and effect sizes were calculated. Pearson's correlations (p < 0.05) calculated relationships between RSA TT and PD with the other tests. There were no significant between-position differences for any test. There were large effects for the faster right-leg 505 and greater YYIRT2 distance for midfielders compared to defenders and forwards. Nonetheless, no between-position differences in RSA TT and PD were documented. There were relationships between RSA TT and the VJ (r = -0.59), SBJ (r = -0.61), 0-10 m (r = 0.64) and 0-30 m (r = 0.83) sprint intervals. There were no significant correlations for RSA PD. Male field players from one collegiate soccer team can demonstrate similar RSA across different positions. Greater lower-body power and sprinting speed could augment RSA.


#2 Pre-season dietary intake of professional soccer players
Reference: Nutr Health. 2017 Jan 1:260106017737014. doi: 10.1177/0260106017737014. [Epub ahead of print]
Authors: Raizel R, Godois ADM, Coqueiro AY, Voltarelli FA, Fett CA, Tirapegui J, Ravagnani FCP, Coelho-Ravagnani CF
Summary: Despite the well-documented importance of nutrition in optimizing performance and health, the dietary intake of soccer players has attracted little attention. We aimed to assess the pre-season dietary intake of professional soccer players and its adequacy in macro and micronutrients. The pre-season dietary intake of 19 male athletes was assessed using a semi-structured 3-day food record. To determine dietary adequacy and excess, energy and macronutrient intake were compared with the Brazilian dietary reference values for athletes, and micronutrients were compared with the Estimated Average Requirement - EAR (minimum recommendation) and Tolerable Upper Intake Level - UL (maximum recommendation). Mean daily energy intake (40.74±12.81 kcal/kg) was adequate. However, there was a low carbohydrate intake (5.44±1.86 g/kg/day) and a high amount of protein and fat (1.91±0.75 and 1.27±0.50 g/kg/day, respectively). Sodium intake (3141.77±939.76 mg/day) was higher than UL (2300 mg/day), while the majority of players showed daily intake of vitamin A (74%), vitamin D (100%), folate (58%), calcium and magnesium (68%) below the EAR (625, 10 and 320 µg/day, 800 and 330 mg/day, respectively). The dietary intake of professional soccer players was adequate in energy, but inadequate in macro and micronutrients, which suggests the need to improve nutritional practices to sustain the physical demands of soccer during pre-season.


#3 Head and neck size and neck strength predict linear and rotational acceleration during purposeful soccer heading
Reference: Sports Biomech. 2017 Oct 16:1-15. doi: 10.1080/14763141.2017.1360385. [Epub ahead of print]
Authors: Caccese JB, Buckley TA, Tierney RT, Arbogast KB, Rose WC, Glutting JJ, Kaminski TW
Summary: There is increasing societal concern about the long-term effects of repeated impacts from soccer heading, but there is little information about ways to reduce head impact severity. The purpose of this study was to identify factors that contribute to head acceleration during soccer heading. One-hundred soccer players completed 12 controlled soccer headers. Peak linear (PLA) and rotational (PRA) accelerations were measured using a triaxial accelerometer and gyroscope. Head acceleration contributing factors were grouped into 3 categories: size (head mass, neck girth), strength (sternocleidomastoid, upper trapezius) and technique [kinematics (trunk, head-to-trunk range-of-motion), sternocleidomastoid and upper trapezius activity]. Multiple regression analyses indicated size variables explained 22.1% of the variance in PLA and 23.3% of the variance in PRA; strength variables explained 13.3% of the variance in PLA and 17.2% of the variance in PRA; technique variables did not significantly predict PLA or PRA. These findings suggest that head and neck size and neck strength predict PLA and PRA. Anthropometric and neck strength measurements should be considered when determining an athlete's readiness to begin soccer heading.


#4 Difference in kick motion of adolescent soccer players in presence and absence of low back pain
Reference: Gait Posture. 2017 Oct 7;59:89-92. doi: 10.1016/j.gaitpost.2017.10.012. [Epub ahead of print]
Authors: Tojima M, Torii S
Summary: Many adolescent soccer players experience low back pain (LBP). However, there are no reports studying the kick motion of adolescent soccer players experiencing LBP. This study aimed to clarify the kick motion of adolescent soccer players in the presence and absence of LBP. We recruited 42 adolescent soccer players and divided them into two groups according to the presence of LBP (LBP group, n=22) and absence of LBP (NBP group, n=20). We measured real-time kick motion using a three-dimensional motion analysis system. We placed 65 spherical markers on each anatomical landmark and calculated the angle of the lumbar spine, center of mass (COM) of the whole body, and displacement of the support foot. We used an unpaired t-test to compare the data between the groups. Compared with the NBP group, the LBP group showed a lateral shift in COM, which increased the duration of kick motion. The presence of LBP affected the posterior positioning of the support foot and restricted the player's lumbar spine from bending laterally. A lateral shift in COM and larger rotation of the lumbar spine could stress the lumbar spine during kick motion. Therefore, coaches and athletic trainers should pay attention to soccer players' lumbar spine rotation and the COM shift during kick motion. This would be important for preventing LBP in adolescent soccer players.


#5 Hamstring muscle injuries in elite football: translating research into practice
Reference: Br J Sports Med. 2017 Oct 19. pii: bjsports-2017-097573. doi: 10.1136/bjsports-2017-097573. [Epub ahead of print]
Authors: Buckthorpe M, Gimpel M, Wright S, Sturdy T, Stride M


#6 A social network analysis of the goal scoring passing networks of the 2016 European Football Championships
Reference: Hum Mov Sci. 2017 Oct 16. pii: S0167-9457(17)30539-0. doi: 10.1016/j.humov.2017.10.001. [Epub ahead of print]
Authors: Mclean S, Salmon PM, Gorman AD, Stevens NJ, Solomon C
Summary: In the current study, social network analysis (SNA) and notational analysis (NA) methods were applied to examine the goal scoring passing networks (GSPN) for all goals scored at the 2016 European Football Championships. The aim of the study was to determine the GSPN characteristics for the overall tournament, between the group and knock out stages, and for the successful and unsuccessful teams. The study also used degree centrality (DC) metrics as a novel method to determine the relative contributions of the pitch locations involved in the GSPN. To determine changes in GSPN characteristics as a function of changing score line, the analysis considered the match status of the game when goals were scored. There were significant differences for SNA metrics as a function of match status, and for the DC metrics in the comparison of the different pitch locations. There were no differences in the SNA metrics for the GSPN between teams in the group and knock out stages, or between the successful and unsuccessful teams. The results indicate that the GSPN had low values for network density, cohesion, connections, and duration. The networks were direct in terms of pitch zones utilised, where 85% of the GSPN included passes that were played within zones or progressed through the zones towards the goal. SNA and NA metrics were significantly different as a function of changing match status. The current study adds to the previous research on goal scoring in football, and demonstrates a novel method to determine the prominent pitch zones involved in the GSPN. These results have implications for match analysis and the coaching process.


#7 "Football is a boys' game": children's perceptions about barriers for physical activity during recess time
Reference: Int J Qual Stud Health Well-being. 2017;12(sup2):1379338. doi: 10.1080/17482631.2017.1379338.
Authors: Martinez-Andres M, Bartolome-Gutierrez R, Rodriguez-Martin B, Pardo-Guijarro MJ, Martinez-Vizcaino V
Summary: The aim of the study was to know the factors that influence boys and girls' perceptions for performing physical activity during playground recess from their own perspective. Ninety-eight schoolchildren aged 8-11 years from five schools from Cuenca (Spain) participated in 22 focus groups and carried out 98 drawings following the socioecological model as a theoretical framework. A content analysis of the transcripts from the focus groups and drawings was carried out by three researchers. Results showed that, in spite of boys and girls identified same barriers, there were gender differences in their perceptions. Gender socialization was the key as central category and helped to understand these differences. Boys preferred play football and this sport had a monopoly on the recess space. Weather was a barrier for boys. Girls and boys, who did not play football, were relegated to peripheral areas and lack of materials was a barrier for them. Teachers were a barrier for all children who did not play football. Thus, in order to promote recess physical activity, researchers, teachers and educational policy makers should take into account gender socialization and promote inclusive non-curricular physical activity in schools.


#8 Effectiveness of above real-time training on decision-making in elite football: A dose-response investigation
Reference: Prog Brain Res. 2017;234:101-116. doi: 10.1016/bs.pbr.2017.08.007. Epub 2017 Sep 22.
Authors: Farahani JJ, Javadi AH, O'Neill BV, Walsh V
Summary: We examined the effects of video-based training in elite footballers' decision-making by presenting videos with training and testing scenarios at above real-time speeds. We also examined different training protocols to establish how much training is beneficial. We found that above real-time training improved accuracy and response time in football decision-making. In terms of scheduling, we found that the benefits were short lasting and did not last beyond 2 weeks.


#9 Elite professional soccer players’ experience of injury prevention
Reference: Cogent Medicine
Authors: Kristiansen JB, Larsson I.
Download link: https://www.cogentoa.com/article/10.1080/2331205X.2017.1389257.pdf
Summary: Injuries are common in professional soccer and might interfere with the ability of the team and the individual player to perform. Several studies have shown the benefits of exercise as a means to prevent injuries in soccer, but research is needed to substantiate, how injury prevention strategies are best implemented. The purpose of this study was to describe and interpret soccer players’ experience of injury prevention. A hermeneutic phenomenological approach was used as described by van Manen. Eight professional Danish soccer players were interviewed with open-ended interviews. The players’ lived experience of injury prevention across all the interviews were shown as the interaction between three overreaching themes: (1) being a part of a performance environment, (2) the need for an individual approach and (3) strong personal ambitions. Interaction between the three themes empowered the players to engage in injury prevention. Professional soccer players’ experience of injury prevention can be interpreted within the four components of the empowerment model: (1) impact, (2) competence, (3) meaningfulness and (4) choice. The presence of the four components empowered the players to engage in injury prevention in the soccer club.



Australian Football
#1 SCAT3 changes from baseline and associations with X2 Patch measured head acceleration in amateur Australian football players
Reference: J Sci Med Sport. 2017 Oct 6. pii: S1440-2440(17)31637-7. doi: 10.1016/j.jsams.2017.09.591. [Epub ahead of print]
Authors: Willmott C, McIntosh AS, Howard T, Mitra B, Dimech-Betancourt B, Donovan J, Rosenfeld JV
Summary: The purpose was to investigate changes from baseline on SCAT3 as a result of football game exposure, and association with X2 Patch measured head acceleration events in amateur Australian footballers. Peak linear acceleration (PLA) of the head (>10 g) was measured by wearable head acceleration sensor X2 Biosystems X-Patch in male (n=34) and female (n=19) Australian footballers. SCAT3 was administered at baseline (B) and post-game (PG). 1394 head acceleration events (HEA) >10 g were measured. Mean and median HEA PLA were recorded as 15.2 g (SD=9.2, range=10.0-115.8) and 12.4 g (IQR=11.0-15.6) respectively. No significant difference in median HEA PLA (g) was detected across gender (p=0.55), however, more HEAs were recorded in males (p=0.03). A greater number (p=0.004) and severity (p<0.001) of symptoms were reported PG than at B. No significant association between number of HEA or median PLA, and SCAT3 change scores (p>0.05 for all), was identified for either gender. Increase in symptom severity post game was not associated with X2 measured HEA. Males sustained more HEA, however HEA PLA magnitude did not differ across gender. Further work on the validation of head acceleration sensors is required and their role in sports concussion research and medical management.


#2 The Influence of Physical Qualities on Activity Profiles of Female Australian Football Match-Play
Reference: Int J Sports Physiol Perform. 2017 Oct 16:1-20. doi: 10.1123/ijspp.2016-0723. [Epub ahead of print]
Authors: Black GM, Gabbett TJ, Johnston RD, Cole MH, Naughton G, Dawson B
Summary: The rapid transition of female Australian football players from amateur to semi-elite competitions has the potential for athletes to be underprepared for match-play. To gain an understanding the match demands of female football, the aims of this study were three-fold: (1) to highlight the physical qualities that discriminate selected and non-selected female Australian Football players, (2) to investigate activity profiles of female Australian Football players, and (3) to gain an understanding of the influence of physical qualities on running performance in female Australian Football match-play. Twenty-two female Australian football (AF) state academy players (mean ± SD age, 23.2 ± 4.5 years) and 27 non-selected players (mean ± SD age, 23.4 ± 4.9 years) participated in this study. The Yo-Yo Intermittent Recovery Test (Level 1), countermovement jump and 30m sprint tests were completed prior to the competitive season. During 14 matches, players wore global positioning system (GPS) units to describe the running demands of female AF match-play. Selected players were faster over 30 metres (ES=0.57; p=0.04) and covered greater distances on the Yo-Yo IR1 test (ES=1.09; p<0.001). Selected midfielders spent greater time on the field and covered greater total distances (ES=0.73-0.85; p<0.009). No differences were reported in relative distances covered between selected and non-selected players (p=0.08). Players who were faster over 5 metres (r= -0.612), and 30-metres (r= -0.807) and performed better on the Yo-Yo IR1 (r=0.489) covered greater high-speed distances during match-play. Selected female AF players were faster and had greater intermittent running ability than players not selected to a State academy program. An emphasis should be placed on the development of physical fitness in this playing group to ensure optimal preparation for the national competition.



American football
#1 High-magnitude head impact exposure in youth football
Reference: J Neurosurg Pediatr. 2017 Oct 17:1-9. doi: 10.3171/2017.5.PEDS17185. [Epub ahead of print]
Authors: Campolettano ET, Gellner RA, Rowson S
Summary: Even in the absence of a clinically diagnosed concussion, research suggests that neurocognitive changes may develop in football players as a result of frequent head impacts that occur during football games and practices. The objectives of this study were to determine the specific situations in which high-magnitude impacts (accelerations exceeding 40 g) occur in youth football games and practices and to assess how representative practice activities are of games with regard to high-magnitude head impact exposure. METHODS A total of 45 players (mean age 10.7 ± 1.1 years) on 2 youth teams (Juniors [mean age 9.9 ± 0.6 years; mean body mass 38.9 ± 9.9 kg] and Seniors [mean age 11.9 ± 0.6 years; mean body mass 51.4 ± 11.8 kg]) wore helmets instrumented with accelerometer arrays to record head impact accelerations for all practices and games. Video recordings from practices and games were used to verify all high-magnitude head impacts, identify specific impact characteristics, and determine the amount of time spent in each activity. RESULTS A total of 7590 impacts were recorded, of which 571 resulted in high-magnitude head impact accelerations exceeding 40 g (8%). Impacts were characterized based on the position played by the team member who received the impact, the part of the field where the impact occurred, whether the impact occurred during a game or practice play, and the cause of the impact. High-magnitude impacts occurred most frequently in the open field in both games (59.4%) and practices (67.5%). "Back" position players experienced a greater proportion of high-magnitude head impacts than players at other positions. The 2 teams in this study structured their practice sessions similarly with respect to time spent in each drill, but impact rates differed for each drill between the teams. CONCLUSIONS High-magnitude head impact exposure in games and practice drills was quantified and used as the basis for comparison of exposure in the 2 settings. In this cohort, game impact rates exceeded those for practice. Back players, who were often positioned in the open field, were shown to experience elevated levels of head impact exposure relative to players at other positions. The analysis also suggests that practice intensity, which may be influenced by coaching style, may also affect high-magnitude head impact exposure. Future studies should investigate this aspect as a factor affecting head impact exposure.


#2 Examination of Risk for Sleep Disordered Breathing among College Football Players
Reference: J Sport Rehabil. 2017 Oct 16:1-24. doi: 10.1123/jsr.2017-0127. [Epub ahead of print]
Authors: Peck B, Renzi T, Peach H, Gaultney J, Marino JS
Summary: Professional football linemen are at risk for sleep disordered breathing (SDB) compared to other types of athletes. It is currently unknown whether collegiate football linemen display a similar risk profile. The objectives were 1) Determine for the first time whether collegiate football linemen show risk for SDB, and 2) Test the hypothesis that SDB risk is higher in collegiate football linemen compared to an athletic comparison group. Male football linemen (n = 21) and track (n = 22) Division I athletes between the ages of 18 and 22 participated in this study.  Participants completed the Multivariable Apnea Prediction (MAP) Index and Epworth Sleepiness Scale (ESS) surveys, validated measures of symptoms of sleep apnea and daytime sleepiness, respectively. Neck and waist circumferences, blood pressure, Mallampati Index (MMPI) and Tonsil Size were determined, followed by body composition assessment using DEXA. Scores from surveys, anthropometric data, MMPI and body composition were used in the statistical analysis. Survey data demonstrated a deficiency in sleep quality and efficiency, coinciding with increased self-reported symptoms of apnea (MAP index=0.79) in college linemen relative to track athletes. Neck circumference (45cm), waist circumference (107.07cm), body mass index (36.64kg/m2) and body fat % (30.19%), all of which exceeded the clinical predictors of risk for obstructive sleep apnea, were significantly greater in linemen compared to track athletes. MAP variables were significantly correlated with MMPI, neck circumference, body fat %, body mass index, and systolic blood pressure (r ≥ .31, p < 0.05), indicating that college football linemen are at increased risk for SDB. Risk factors for SDB recognized in professional football linemen are also present at the collegiate level. Screening may minimize present or future risk for SDB, as well as the downstream risk of SDB-associated metabolic and cardiovascular disease.



Mon

23

Oct

2017

Football is...(#33)

Short and long shots + different angles = complexity of goal defending

Mon

23

Oct

2017

Football is...(#32)

utilizing both feet - not only for running!

Fri

20

Oct

2017

Football is...(#31)

Dribbling can also be used to improve aerobic endurance.

Thu

19

Oct

2017

Small-sided games website update

The Small-sided training part on the website was updated with some research.

 

If you want to know everything about small-sided games you should read the updated section and click HERE.

Wed

18

Oct

2017

Football is...(#30)

Training one-touch play for promising goal scoring opportunities.

Wed

18

Oct

2017

Football is...(#29)

The core connects arms and legs - train it use it.

Mon

16

Oct

2017

Football is...(#28)

Skillful players have a good first touch.

Mon

16

Oct

2017

Latest research in football - week 41 - 2017

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 Unloaded vs. Loaded Plyometrics on Speed and Power Performance of Elite Young Soccer Players
Reference: Front Physiol. 2017 Sep 26;8:742. doi: 10.3389/fphys.2017.00742. eCollection 2017.
Authors: Kobal R, Pereira LA, Zanetti V, Ramirez-Campillo R, Loturco I
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5623051/pdf/fphys-08-00742.pdf
Summary: The purpose of this study was to investigate the effects of loaded and unloaded plyometric training strategies on speed and power performance of elite young soccer players. Twenty-three under-17 male soccer players (age: 15.9 ± 1.2 years, height: 178.3 ± 8.1 cm, body-mass (BM): 68.1 ± 9.3 kg) from the same club took part in this study. The athletes were pair-matched in two training groups: loaded vertical and horizontal jumps using an haltere type handheld with a load of 8% of the athletes' body mass (LJ; n = 12) and unloaded vertical and horizontal plyometrics (UJ; n = 11). Sprinting speeds at 5-, 10-, and 20-m, mean propulsive power (MPP) relative to the players' BM in the jump squat exercise, and performance in the squat jump (SJ) and countermovement jump (CMJ) were assessed pre- and post-training period. During the experimental period, soccer players performed 12 plyometric training sessions across a 6-week preseason period. Magnitude based inferences and standardized differences were used for statistical analysis. A very likely increase in the vertical jumps was observed for the LJ group (99/01/00 and 98/02/00 for SJ and CMJ, respectively). In the UJ group a likely increase was observed for both vertical jumps (83/16/01 and 90/10/00, for SJ and CMJ, respectively). An almost certainly decrease in the sprinting velocities along the 20-m course were found in the LJ group (00/00/100 for all split distances tested). Meanwhile, in the UJ likely to very likely decreases were observed for all sprinting velocities tested (03/18/79, 01/13/86, and 00/04/96, for velocities in 5-, 10-, and 20-m, respectively). No meaningful differences were observed for the MPP in either training group (11/85/04 and 37/55/08 for LJ and UJ, respectively). In summary, under-17 professional soccer players increased jumping ability after a 6-week preseason training program, using loaded or unloaded jumps. Despite these positive adaptations, both plyometric strategies failed to produce worthwhile improvements in maximal speed and power performances, which is possible related to the interference of concurrent training effects. New training strategies should be developed to ensure adequate balance between power and endurance loads throughout short (and high-volume) soccer preseasons.


#2 Soccer-based promotion of voluntary medical male circumcision: A mixed-methods feasibility study with secondary students in Uganda
Reference: PLoS One. 2017 Oct 9;12(10):e0185929. doi: 10.1371/journal.pone.0185929. eCollection 2017.
Authors: Miiro G, DeCelles J, Rutakumwa R, Nakiyingi-Miiro J, Muzira P, Ssembajjwe W, Musoke S, Gibson LJ, Hershow RB, Francis S, Torondel B, Ross DA, Weiss HA
Download link: http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0185929&type=printable
Summary: The Ugandan government is committed to scaling-up proven HIV prevention strategies including safe male circumcision, and innovative strategies are needed to increase circumcision uptake. The aim of this study was to assess the acceptability and feasibility of implementing a soccer-based intervention ("Make The Cut") among schoolboys in a peri-urban district of Uganda. The intervention was led by trained, recently circumcised "coaches" who facilitated a 60-minute session delivered in schools, including an interactive penalty shoot-out game using metaphors for HIV prevention, sharing of the coaches' circumcision story, group discussion and ongoing engagement from the coach to facilitate linkage to male circumcision. The study took place in four secondary schools in Entebbe sub-district, Uganda. Acceptability of safe male circumcision was assessed through a cross-sectional quantitative survey. The feasibility of implementing the intervention was assessed by piloting the intervention in one school, modifying it, and implementing the modified version in a second school. Perceptions of the intervention were assessed with in-depth interviews with participants. Of the 210 boys in the cross-sectional survey, 59% reported being circumcised. Findings showed high levels of knowledge and generally favourable perceptions of circumcision. The initial implementation of Make The Cut resulted in 6/58 uncircumcised boys (10.3%) becoming circumcised. Changes made included increasing engagement with parents and improved liaison with schools regarding the timing of the intervention. Following this, uptake improved to 18/69 (26.1%) in the second school. In-depth interviews highlighted the important role of family and peer support and the coach in facilitating the decision to circumcise. This study showed that the modified Make The Cut intervention may be effective to increase uptake of safe male circumcision in this population. However, the intervention is time-intensive, and further work is needed to assess the cost-effectiveness of the intervention conducted at scale.


#3 The Effects of Foam Rolling as a Recovery Tool in Professional Soccer Players
Reference: J Strength Cond Res. 2017 Oct 7. doi: 10.1519/JSC.0000000000002277. [Epub ahead of print]
Authors: Rey E, Padron-Cabo A, Costa PB, Barcala-Furelos R
Summary: Foam rolling (FR) is a common strategy used after training and competition by players. However, no previous studies have assessed the effectiveness of FR as recovery tool in sports populations. The aim of this study was to examine the effectiveness of FR (20 minutes of foam rolling exercises on quadriceps, hamstrings, adductors, gluteals, and gastrocnemius) and passive recovery (20 minutes sit on a bench) interventions performed immediately after a training session on Total Quality Recovery (TQR), perceived muscle soreness, jump performance, agility, sprint, and flexibility 24 hours after the training. During 2 experimental sessions, 18 professional soccer players (age 26.6 ± 3.3 years; height: 180.2 ± 4.5 cm; body mass: 75.8 ± 4.7 kg) participated in a randomized fully controlled trial design. The first session was designed to collect the pre-test values of each variable. After baseline measurements, the players performed a standardized soccer training. At the end of training unit, all the players were randomly assigned to the FR recovery group and the passive recovery group. A second experimental session was carried out to obtain the posttest values. Results from the between-group analyses showed that FR had a large effect on the recovery in agility (Effect Sizes [ES]= 1.06), TQR (ES= 1.08), and perceived muscle soreness (ES= 1.02) in comparison to passive recovery group at 24 h post-training. Thus, it is recommended soccer coaches and physical trainers working with high-level players use a structured recovery session lasting from 15 to 20 min based on FR exercises that could be implemented at the end of a training session to enhance recovery between training loads.


#4 Injury prevention in male youth soccer: Current practices and perceptions of practitioners working at elite English academies
Reference: J Sports Sci. 2017 Oct 11:1-9. doi: 10.1080/02640414.2017.1389515. [Epub ahead of print]
Authors: Read PJ, Jimenez P, Oliver JL, Lloyd RS
Summary: Forty-one practitioners inclusive of physiotherapists, sports scientists and strength and conditioning coaches from the academies of elite soccer clubs in the United Kingdom completed an on-line questionnaire which examined their: (1) background information; (2) perceptions of injury occurrence and risk factors; (3) screening and return to play; and (4) approach to designing and delivering injury prevention programmes with a response rate of 55% (41/75). Contact injuries were the most common mechanism reported and players between 13-16 years of age were perceived to be at the greatest risk. Pertinent risk factors included: reduced lower limb and eccentric hamstring strength, proprioception, muscle imbalances, and under developed foundational movement skills. Joint range of motion, jump tests, the functional movement screen, overhead and single leg squats were the most utilised screening methods. Training modalities rated in order of importance included: resistance training, flexibility development, agility, plyometrics and balance training. Training frequency was most commonly once or twice per week, during warm-ups, independent sessions or a combination of both. Injury prevention strategies in this cohort appear to be logical; however, the classification of injury occurrence and application of screening tools to identify "at risk" players do not align with existing research. The frequency and type of training used may also be insufficient to elicit an appropriate stimulus to address pertinent risk factors based on current recommendations.


#5 The physical response to a simulated period of soccer-specific fixture congestion
Reference: J Strength Cond Res. 2017 Oct 10. doi: 10.1519/JSC.0000000000002257. [Epub ahead of print]
Authors: Page RM, Marrin K, Brogden CM, Greig M
Summary: The aim of this study was to assess the physiological, perceptual, and mechanical measures associated with the completion of a simulated period of short-term soccer-specific fixture congestion. Ten male semi-professional soccer players completed three trials of a treadmill-based match simulation, with 48 hours intervening each trial. A repeated measures general linear model identified significantly (P= 0.02) lower knee flexor peak torque (PT) recorded at 300 degs[BULLET OPERATOR]s in the second (141.27 ± 28.51 Nm) and third trials (139.12 ± 26.23 Nm) when compared to the first (154.17 ± 35.25 Nm). Similarly, muscle soreness (MS) and PT data recorded at 60 degs[BULLET OPERATOR]s were significantly (P< 0.05) different in the third trial (MS= 42 ± 25 a.u; PT60= 131.10 ± 35.38 Nm) when compared to the first (MS= 29 ± 29 a.u; PT60= 145.61 ± 42.86 Nm). Significant (P= 0.003) differences were also observed for mean Bicep Femoris electromyography (EMGmean) between the third trial (T0-15= 126.36 ± 15.57 µV; T75-90= 52.18 ± 17.19 µV) and corresponding time points in the first trial (T0-15= 98.20 ± 23.49 µV; T75-90= 99.97 ± 39.81 µV). Cumulative increases in perceived exertion, heart rate, oxygen consumption, blood lactate concentrations, EMGmean, and PlayerLoad were recorded across each trial. MS and PT were also significantly different post-trial. There were however no significant main effects or interactions for the salivary Immunoglobulin A, and the medial-lateral PlayerLoad metrics. These data suggest a biomechanical and muscular emphasis with residual fatigue, with implications for injury risk and the development of recovery strategies.


#6 Steroid hormones and psychological responses to soccer matches: Insights from a systematic review and meta-analysis
Reference: PLoS One. 2017 Oct 12;12(10):e0186100. doi: 10.1371/journal.pone.0186100. eCollection 2017.
Authors: Slimani M, Baker JS, Cheour F, Taylor L, Bragazzi NL
Download link: http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0186100&type=printable
Summary: The present systematic review and meta-analysis aimed to assess the perturbations in hormonal and psychological homeostasis in response to soccer match-play. These perturbations were explored according to match outcome (i.e., win versus loss), gender, type of contest (i.e., competitive versus non-competitive fixtures) and competitive level (i.e., novice versus high-level). The review was conducted according to the Population/Intervention or Exposure/Comparison/Outcome(s) (PICO) criteria and the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Match outcome, type of contest and competitive levels were moderator variables in the examined steroid hormones responses to a soccer match-play. Different testosterone responses were seen between match winners (increase) and losers (decrease) when compared to pre-game or baseline values (p <0.05), whilst no changes could be detected for cortisol relative to match outcome in female soccer players. Males (Δ% = 6.26; ES = 0.28) demonstrated a marginally lower increase in testosterone levels when compared to females (Δ% = 49.16; ES = 1.00), though not statistically significant. Females (Δ% = 162.7; ES = 0.98) did not demonstrate elevated cortisol match response compared to males (Δ% = 34.60; ES = 1.20). Male novice soccer match-play increased cortisol levels compared to high-level soccer match-play (Q = 18.08, p<0.001). Competitive soccer matches increased cortisol levels compared to non-competitive fixtures (i.e., collegiate tournament). Additionally, competitive levels moderate the relationship between a soccer match and testosterone levels (p <0.001), regardless of gender differences. From the presented systematic review and meta-analysis it appears (1) cortisol changes are associated with cognitive anxiety in starter female soccer players, while (2) testosterone changes are associated with changes in mood state in females and social connectedness in male soccer players. This apparent psycho-physiological relationship may proffer the opportunity for targeted intervention(s) by practitioners to favorably influence performance and/or recovery agendas. Further mechanistic and/or applied evidence is required in this regard in addition to further data sets from females.


#7 Effects of Plyometric Training on Components of Physical Fitness in Prepuberal Male Soccer Athletes: The Role of Surface Instability
Reference: J Strength Cond Res. 2017 Oct 10. doi: 10.1519/JSC.0000000000002262. [Epub ahead of print]
Authors: Negra Y, Chaabene H, Sammoud S, Bouguezzi R, Mkaouer B, Hachana Y, Granacher U
Summary: Previous studies contrasted the effects of plyometric training (PT) conducted on stable vs. unstable surfaces on components of physical fitness in child and adolescent soccer players. Depending on the training modality (stable vs. unstable), specific performance improvements were found for jump (stable PT) and balance performances (unstable PT). In an attempt to combine the effects of both training modalities, this study examined the effects of PT on stable surfaces compared with combined PT on stable and unstable surfaces on components of physical fitness in prepuberal male soccer athletes. Thirty-three boys were randomly assigned to either a PT on stable surfaces (PTS; n = 17; age = 12.1 ± 0.5 years; height = 151.6 ± 5.7 cm; body mass = 39.2 ± 6.5 kg; and maturity offset = -2.3 ± 0.5 years) or a combined PT on stable and unstable surfaces (PTC; n = 16; age = 12.2 ± 0.6 years; height = 154.6 ± 8.1 cm; body mass = 38.7 ± 5.0 kg; and maturity offset = -2.2 ± 0.6 years). Both intervention groups conducted 4 soccer-specific training sessions per week combined with either 2 PTS or PTC sessions. Before and after 8 weeks of training, proxies of muscle power (e.g., countermovement jump [CMJ], standing long jump [SLJ]), muscle strength (e.g., reactive strength index [RSI]), speed (e.g., 20-m sprint test), agility (e.g., modified Illinois change of direction test [MICODT]), static balance (e.g., stable stork balance test [SSBT]), and dynamic balance (unstable stork balance test [USBT]) were tested. An analysis of covariance model was used to test between-group differences (PTS vs. PTC) at posttest using baseline outcomes as covariates. No significant between-group differences at posttest were observed for CMJ (p > 0.05, d = 0.41), SLJ (p > 0.05, d = 0.36), RSI (p > 0.05, d = 0.57), 20-m sprint test (p > 0.05, d = 0.06), MICODT (p > 0.05, d = 0.23), and SSBT (p > 0.05, d = 0.20). However, statistically significant between-group differences at posttest were noted for the USBT (p < 0.01, d = 1.49) in favor of the PTC group. For most physical fitness tests (except RSI), significant pre-to-post improvements were observed for both groups (p < 0.01, d = 0.55-3.96). Eight weeks of PTS or PTC resulted in similar performance improvements in components of physical fitness except for dynamic balance. From a performance-enhancing perspective, PTC is recommended for pediatric strength and conditioning coaches because it produced comparable training effects as PTS on proxies of muscle power, muscle strength, speed, agility, static balance, and additional effects on dynamic balance.


American Football
#1 Heart Rate Variability and Training Load Among National Collegiate Athletic Association Division 1 College Football Players Throughout Spring Camp
Reference: J Strength Cond Res. 2017 Oct 10. doi: 10.1519/JSC.0000000000002241. [Epub ahead of print]
Authors: Flatt AA, Esco MR, Allen JR, Robinson JB, Earley RL, Fedewa MV, Bragg A, Keith CM, Wingo JE
Summary: The purpose of this study was to determine whether recovery of cardiac-autonomic activity to baseline occurs between consecutive-day training sessions among positional groups of a collegiate football team during Spring camp. A secondary aim was to evaluate relationships between chronic (i.e., 4-week) heart rate variability (HRV) and training load parameters. Baseline HRV (lnRMSSD_BL) was compared with HRV after ∼20 hours of recovery before next-day training (lnRMSSDpost20) among positional groups composed of SKILL (n = 11), MID-SKILL (n = 9), and LINEMEN (n = 5) with a linear mixed model and effect sizes (ES). Pearson and partial correlations were used to quantify relationships between chronic mean and coefficient of variation (CV) of lnRMSSD (lnRMSSD_chronic and lnRMSSDcv, respectively) with the mean and CV of PlayerLoad (PL_chronic and PL_cv, respectively). A position × time interaction was observed for lnRMSSD (p = 0.01). lnRMSSD_BL was higher than lnRMSSDpost20 for LINEMEN (p < 0.01; ES = large), whereas differences for SKILL and MID-SKILL were not statistically different (p > 0.05). Players with greater body mass experienced larger reductions in lnRMSSD (r = -0.62, p < 0.01). Longitudinally, lnRMSSDcv was significantly related to body mass (r = 0.48) and PL_chronic (r = -0.60). After adjusting for body mass, lnRMSSDcv and PL_chronic remained significantly related (r = -0.43). The ∼20-hour recovery time between training sessions on consecutive days may not be adequate for restoration of cardiac-parasympathetic activity to baseline among LINEMEN. Players with a lower chronic training load throughout camp experienced greater fluctuation in lnRMSSD (i.e., lnRMSSDcv) and vice versa. Thus, a capacity for greater chronic workloads may be protective against perturbations in cardiac-autonomic homeostasis among American college football players.


#2 Longitudinal Changes in Body Composition throughout Successive Seasonal Phases among Canadian University Football Players
Reference: J Strength Cond Res. 2017 Oct 7. doi: 10.1519/JSC.0000000000002011. [Epub ahead of print]
Authors: Kim J, Delisle-Houde P, Reid RE, Andersen RE.
Summary: The purpose of this study was to assess changes in body composition during seasonal phases of the training year among Canadian Inter-University Sport (CIS) football players. Forty university football players were assessed for anthropometry, total body composition, regional body composition and central adiposity over a 7-month period including the summer-off-season and the in-season. Baseline testing occurred in April, prior to the summer-off-season, and follow-ups were completed prior to training camp, at the beginning of August, and following the in-season, at the beginning of November. Linemen had the greatest tissue percent fat (25.98 ± 6.56%) at baseline, significantly (p < 0.01) greater than big skill (18.69 ± 3.97%) and followed by skill (14.35 ± 3.39%) who were significantly (p < 0.01) leaner than both other groups. Skill players significantly increased fat mass (0.98 ± 0.30 kg, p < 0.05) and waist-to-hip ratio (WHR; 0.02 ± 0.01, p ≤ 0.05) during the in-season, and linemen increased visceral fat mass from April to November (0.20 ± 0.06 kg, p ≤ 0.01). All players significantly (-1.26 ± 0.30 kg, p = 0.001) decreased lean mass during the in-season. All groups significantly increased bone mineral content during the summer-off-season (p < 0.05). There was also a significant time × summer training location interaction (p < 0.05) for fat mass with athletes who remained on campus during summer months gaining the least amount of adiposity. Body composition and central adiposity appear to change differentially among positional groups across the annual training season.


#3 Age at First Exposure to Repetitive Head Impacts Is Associated with Smaller Thalamic Volumes in Former Professional American Football Players
Reference: J Neurotrauma. 2017 Oct 7. doi: 10.1089/neu.2017.5145. [Epub ahead of print]
Authors: Schultz V, Stern RA, Tripodis Y, Stamm JM, Wrobel P, Lepage C, Weir I, Guenette JP, Chua A, Alosco ML, Baugh CM, Fritts NG, Martin B, Chaisson C, Coleman MJ, Lin AP, Pasternak O, Shenton ME, Koerte IK
Summary: Thalamic atrophy has been associated with exposure to repetitive head impacts (RHI) in professional fighters. The aim of this study is to investigate whether or not age at first exposure (AFE) to RHI is associated with thalamic volume in symptomatic former National Football League (NFL) players at risk for chronic traumatic encephalopathy (CTE). Eighty-six symptomatic former NFL players (mean age=54.9±7.9 years) were included. T1-weighted data were acquired on a 3T MRI and thalamic volumes were derived using FreeSurfer. Mood and behavior, psychomotor speed, and visual and verbal memory were assessed. The association between thalamic volume and AFE to playing football, and to number of years playing were calculated. Decreased thalamic volume was associated with more years of play (left: p=0.03; right: p=0.03). Younger AFE was associated with decreased right thalamic volume (p=0.014). This association remained significant after adjusting for total years of play. Decreased left thalamic volume was associated with worse visual memory (p=0.014), whereas increased right thalamic volume was associated with fewer mood and behavior symptoms (p=0.003). In our sample of symptomatic former NFL players at risk for CTE, total years of play, and AFE were associated with decreased thalamic volume. The effect of AFE on right thalamic volume was almost twice as strong as the effect of total years of play. Our findings confirm previous reports of an association between thalamic volume and exposure to RHI. They further suggest that younger AFE may result in smaller thalamic volume later in life.


#4 Anthropometrics and maturity status: A preliminary study of youth football head impact biomechanics
Reference: Int J Psychophysiol. 2017 Oct 3. pii: S0167-8760(17)30580-9. doi: 10.1016/j.ijpsycho.2017.09.022. [Epub ahead of print]
Authors: Yeargin SW, Kingsley P, Mensch JM, Mihalik JP, Monsma EV
Summary: There is a paucity of head impact biomechanics research focusing on youth athletes. Little is known about how youth subconcussive head impact tolerances are related to physical size and maturation. The objective was to examine the effects of age, anthropometric and maturational status variability on head impact biomechanics. Thirty-four male recreational youth football players, 8 to 13yrs participated in this study. Categorized by CDC standards, independent variables were: age, height, mass, BMI, and estimated peak height velocity (PHV). Participants wore a designated head impact sensor (xPatch) on their mastoid process during practices and games. Main outcome measures were Linear acceleration (g) and rotational acceleration (rad/s2). Boys in the older age category had a greater linear (F=17.72; P<0.001) and rotational acceleration (F=10.74; P<0.001) than those in the younger category. Post-PHV boys had higher linear (F=9.09, P=0.002) and rotational (F=5.57, P=0.018) accelerations than those who were pre-PHV. Rotational, but not linear acceleration differed by height category with lowest impacts found for the tallest category, whereas both linear and rotational accelerations by mass differences favored average and heavy categories. BMI overweight boys, had the greatest linear (F=5.25; P=0.011) and rotational acceleration (F=4.13; P=0.260) means. Post-PHV boys who were older, taller and had longer legs, but who were not heavier, had higher impacts perhaps due to the type of impacts sustained. Taller boys' heads are above their peers possibly encouraging hits in the torso region resulting in lower impact accelerations. Obese boys did not have sequential results compared to boys in the other BMI categories probably due to league rules, player position, and lack of momentum produced.

Mon

16

Oct

2017

Football is...(#27)

SSG = Technical + Tactical + Physical Training

Fri

13

Oct

2017

Football is...(#26)

Numerical (dis)advantages can be crucial.

Thu

12

Oct

2017

Football is...(#25)

Testing players intermittent running capacity - a suggestion.

Wed

11

Oct

2017

Latest research in football - week 40 - 2017

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 Professional football players at risk for non-acute groin injuries during the first half of the season: A prospective cohort study in The Netherlands
Reference: J Back Musculoskelet Rehabil. 2017 Sep 15. doi: 10.3233/BMR-150427. [Epub ahead of print]
Authors: Gouttebarge V, Veenstra E, Goedegebuure S, Frings-Dresen M, Kuijer P
Summary: The purpose was to study the incidence, diagnostics, treatment, anatomical region and return to play of non-acute groin injuries among professional footballers in the Netherlands. Medical staff members of all Dutch professional football clubs, recording prospectively injury occurrence of all professional footballers in their clubs, were asked to fill in an injury form about time-loss (⩾ 8 days) non-acute groin injury over the 2012-2013 season. A cohort of 410 players from 12 professional football clubs were included (response rate = 44%). The season incidence of non-acute groin injuries was nearly 7% (29 non-acute groin injuries). In 82% of all cases, the player suffered from non-acute groin injury in the first half of the season. The average time to return to play was 35 days, ranging from 8 to 84 days. The adductors were the most affected anatomical regions (82%), with the most frequent diagnosis being overuse of the adductors (36%), followed by adductor tendinopathy (18%). In addition to medical history and physical examination, ultrasound (50%) and MRI (32%) were the diagnostic methods most frequently mentioned. As well as physical therapy, treatment consisted mostly of manual therapy (96%) and dry needling (61%). A professional club with a squad of 25 players can expect on average two non-acute groin injuries per season with an average time-loss of 35 days. Players are more at risk in the first half of the season. In Dutch professional football, ultrasound is commonly used to diagnose non-acute groin injury, while manual therapy is the most commonly applied treatment.


#2 Osteitis pubis in professional football players: MRI findings and correlation with clinical outcome
Reference: Eur J Radiol. 2017 Sep;94:46-52. doi: 10.1016/j.ejrad.2017.07.009. Epub 2017 Jul 19.
Authors: Gaudino F, Spira D, Bangert Y, Ott H, Beomonte Zobel B, Kauczor HU, Weber MA
Summary: Osteitis pubis (OP), a common pathology in elite athletes, is an aseptic inflammatory process of the pubic symphysis bone, and may involve surrounding soft tissues, tendons and muscles. OP is typically characterized by (often recurring) groin pain and is an important cause of time-off from sports activity in athletes. Aim of this retrospective study was to analyze magnetic resonance imaging (MRI) findings in professional football players with clinical diagnosis of OP and to correlate MRI findings with clinical outcome. All professional football players (23 males, 1 female; mean age: 21±3.7years; range: 16-30 years) with groin pain and clinical diagnosis of OP, who underwent pelvic MRI in our institution were retrospectively analyzed. The MR images were analyzed regarding the presence of bone marrow edema and its extension, whether fluid in the symphysis pubis or periarticular soft tissue edema with a rim-like periosteal distribution or edema in the muscles located around the symphyseal joint were present, whether degenerative changes of the symphysis pubis and of signs of symphyseal instability were encountered. A quantitative measurement of the signal intensity in bone marrow edema on 3T STIR sequences was performed, normalizing these values to the mean signal intensity values in the ipsilateral iliopsoas muscle. All patients were classified according to a 3-point grading scale. For each patient, both the symptoms 18 months after the initial MRI examination, the duration of time off from playing football and the kind of treatment applied were evaluated. Among all professional athletes, in 20/24 (83.3%) MRI showed signs of OP with bone marrow edema at the pubic bone. 12 of these patients showed complete clinical recovery without any symptoms after 18 months, while in 8 patients partial recovery with persistence of groin pain during higher sports activity was observed. Patients with edema in periarticular soft tissues or in the muscles around the symphyseal joint on MRI at the beginning of symptoms presented significantly more often with a partial recovery after returning to high sports activity (p=0.042 and p=0.036, respectively). A partial recovery was also significantly associated with higher normalized mean signal intensity values in bone marrow edema on STIR sequences at the beginning of symptoms (mean=4.77±1.63 in the group with partial recovery vs. mean=2.86±0.45 in the group with complete recovery; p=0.0019). No significant association was noticed between MRI findings and time of abstinence from high sports activity, as well as between the 3-point grading scale and the time off from high sport activity and recovery at 18 months. Edema in periarticular soft tissues, edema with extension to the muscles located around the symphyseal joint, as well as higher normalized signal intensity values in bone marrow edema on STIR sequences in the pubic bones at the beginning of groin pain are the most reliable MRI findings of a poor clinical long-term outcome of OP in professional football players and should be regarded as negative prognostic factors.


#3 Applying graphs and complex networks to football metric interpretation
Reference: Hum Mov Sci. 2017 Sep 20. pii: S0167-9457(17)30628-0. doi: 10.1016/j.humov.2017.08.022. [Epub ahead of print]
Authors: Arriaza-Ardiles E, Martin-Gonzalez JM, Zuniga MD, Sanchez-Flores J, de Saa Y, Garcia-Manso JM
Summary: This work presents a methodology for analysing the interactions between players in a football team, from the point of view of graph theory and complex networks. We model the complex network of passing interactions between players of a same team in 32 official matches of the Liga de Fútbol Profesional (Spain), using a passing/reception graph. This methodology allows us to understand the play structure of the team, by analysing the offensive phases of game-play. We utilise two different strategies for characterising the contribution of the players to the team: the clustering coefficient, and centrality metrics (closeness and betweenness). We show the application of this methodology by analyzing the performance of a professional Spanish team according to these metrics and the distribution of passing/reception in the field. Keeping in mind the dynamic nature of collective sports, in the future we will incorporate metrics which allows us to analyse the performance of the team also according to the circumstances of game-play and to different contextual variables such as, the utilisation of the field space, the time, and the ball, according to specific tactical situations.


#4 Mental Fatigue and Spatial References Impair Soccer Players' Physical and Tactical Performances
Reference: Front Psychol. 2017 Sep 21;8:1645. doi: 10.3389/fpsyg.2017.01645. eCollection 2017.
Authors: Coutinho D, Gonçalves B, Travassos B, Wong DP, Coutts AJ, Sampaio JE
Summary: This study examined the effects of mental fatigue and additional corridor and pitch sector lines on players' physical and tactical performances during soccer small-sided games. Twelve youth players performed four Gk+6vs6+Gk small-sided games. Prior to the game, one team performed a motor coordination task to induce mental fatigue, while the other one performed a control task. A repeated measures design allowed to compare players' performances across four conditions: (a) with mental fatigue against opponents without mental fatigue in a normal pitch (MEN), (b) with mental fatigue on a pitch with additional reference lines (#MEN); (c) without mental fatigue against mentally fatigued opponents on a normal pitch (CTR); and (d) without mental fatigue on a pitch with reference lines (#CTR). Player's physical performance was assessed by the distance covered per minute and the number of accelerations and decelerations (0.5-3.0 m/s2; > -3.0 m/s2). Positional data was used to determine individual (spatial exploration index, time synchronized in longitudinal and lateral directions) and team-related variables (length, width, speed of dispersion and contraction). Unclear effects were found for the physical activity measures in most of the conditions. There was a small decrease in time spent laterally synchronized and a moderate decrease in the contraction speed when MEN compared to the CTR. Also, there was a small decrease in the time spent longitudinally synchronized during the #MEN condition compared to MEN. The results showed that mental fatigue affects the ability to use environmental information and players' positioning, while the additional reference lines may have enhanced the use of less relevant information to guide their actions during the #MEN condition. Overall, coaches could manipulate the mental fatigue and reference lines to induce variability and adaptation in young soccer players' behavior.


#5 Exercise physiology and nutritional perspectives of elite soccer refereeing
Reference: Scand J Med Sci Sports. 2017 Oct 5. doi: 10.1111/sms.12989. [Epub ahead of print]
Authors: Schenk K, Bizzini M, Gatterer H
Summary: Referees are an integral part of soccer and their performance is fundamental for regular match flow, irrespective of the competition level or age classes. So far, scientific interest was mainly limited to aspects of exercise physiology and match performance of soccer referees, whereas recommendations for nutrition were adopted from active professional soccer. In contrast to elite soccer players most referees are non-professional and engaged in different occupations. Furthermore, elite referees and soccer players differ in regard to age, body composition, aerobic capacity and training load. Thus, referees' caloric needs and recommended daily carbohydrate intake may generally be lower compared to active soccer players, with higher intakes limited to periods of increased training load and match days or for referees engaged in physical demanding occupations. With respect to fluid intake, pre-match and in-match hydration strategies generally valid in sports are recommended also for referees to avoid cognitive and physical performance loss, especially when officiating in extreme climates and altitude. In contrast to elite soccer, professional assistance concerning nutrition and training is rarely available for national elite referees of most countries. Therefore, special attention on education about adequate nutrition and fluid intake, about the dietary prevention of deficiencies (iron in female referees, vitamin D irrespective of sex and age) and basic precautions for travels abroad is warranted. In conclusion, the simple adoption of nutritional considerations from active soccer for referees may not be appropriate. Recommendations should respect gender differences, population specific physical characteristics and demands just as well as individual characteristics and special needs.


#6 A rare case of localised pigmented villonodular synovitis in the knee of a 24-year-old female soccer player: diagnosis, management and summary of tenosynovial giant cell tumours
Reference: BMJ Case Rep. 2017 Oct 4;2017. pii: bcr-2017-219549. doi: 10.1136/bcr-2017-219549.
Authors: Falster C, Stockmann Poulsen S, Joergensen U
Summary: Localised pigmented villonodular synovitis (PVNS) of the knee is a rare diagnosis, with clinical signs and symptoms mimicking meniscal damage or other common knee injuries.We report the case of a 24-year-old female soccer player, seeking treatment after 7 months of persisting knee pain. Additionally, we present an overview of tenosynovial giant cell tumours.On examination, the patient was found to have tenderness in the medial joint space of the knee. MRI revealed a heterogeneous formation in the central part of the knee. The formation was completely enucleated arthroscopically, histological analyses confirmed the diagnosis of localised PVNS. The patient was subsequently free of symptoms with no signs of recurrence on MRI and had resumed soccer practice at the 1-year follow-up appointment.


#7 Genetic Variants and Hamstring Injury in Soccer: an Association and Validation Study
Reference: Med Sci Sports Exerc. 2017 Oct 2. doi: 10.1249/MSS.0000000000001434. [Epub ahead of print]
Authors: Larruskain J, Celorrio D, Barrio I, Odriozola A, Gil SM, Fernandez-Lopez JR, Nozal R, Ortuzar I, Lekue JA, Aznar JM.
Summary: The purpose was to investigate the association of candidate single nucleotide polymorphisms (SNPs) with non-contact hamstring muscle injuries in elite soccer players, and to create and validate a model to assess the risk of hamstring injury. 107 elite male outfield players were prospectively followed for 6 seasons. Players were genotyped for 37 SNPs previously investigated in relation to musculoskeletal injuries. The association of SNPs, previous injury, age, level of play, position and anthropometric data with 129 hamstring injuries (413 observations) was investigated in the discovery phase (2010-2015), and a multivariable Cox-frailty model was created using forward selection. The model's discriminative ability was tested in the validation phase (2015-2016, 31 injuries, 98 observations) using Harrell's C index. Five SNPs were found to be significantly associated with hamstring injury in a multivariable model, MMP3 (Matrix metalloproteinase-3) rs679620 (A vs. G, hazard ratio (HR)=2.06, 95% confidence interval (CI)=1.51-2.81), TNC (Tenascin-C) rs2104772 (A vs. T, HR=1.65, 95% CI=1.17-2.32), IL6 (Interleukin-6) rs1800795 (GG vs. GC+CC, HR=1.68, 95% CI=1.11-2.53), NOS3 (Nitric oxide synthase-3) rs1799983 (G vs. T, HR=1.35, 95% CI=1.01-1.79), and HIF1A (Hypoxia-inducible factor-1α) rs11549465 (CC vs. CT, HR=2.08, 95% CI=1.00-4.29). Age also entered the model (≥24 vs. <24 years, HR=2.10, 95% CI=1.29-3.42). The model showed acceptable discrimination in the discovery phase (C index=0.74), but not in the validation phase (C index=0.52). Genetic variants appear to be involved in the etiology of hamstring injuries, but were not found to have predictive value by themselves. Further research, increasing the number of genetic variants and including environmental factors in complex multifactorial risk models is necessary.


#8 Prevalence of femoroacetabular impingement morphology in asymptomatic youth soccer players: magnetic resonance imaging study with clinical correlation
Reference: Rev Bras Ortop. 2017 Jun 24;52(Suppl 1):14-20. doi: 10.1016/j.rboe.2017.06.005. eCollection 2017.
Authors: Yepez AK, Abreu M, Germani B, Galia CR
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5620002/pdf/main.pdf
Summary: The purpose was to determine the prevalence of femoroacetabular impingement morphology (FAIM), cam- or pincer-type, by magnetic resonance imaging (MRI) in asymptomatic adolescent soccer players, and to evaluate the possible correlation between alterations on MRI and clinical examination findings. A cross-sectional study was conducted to determine the prevalence of FAIM in asymptomatic youth soccer players aged 13-18 years. A total of 112 hips in 56 players (mean age 15.3 years) were evaluated by MRI. Images were examined by two musculoskeletal radiologists for signs of FAIM. Cam-type (impingement) deformity was diagnosed by alpha angle ≥55° or head-neck offset <7 mm. Pincer-type (impingement) deformity was diagnosed by center-edge angle (CEA) ≥35° or acetabular index ≤0°. Other MRI changes, characteristic of FAIM, were observed. Clinical examination was performed to determine the range of motion (ROM) of the hips. In addition, specific tests for anterolateral and posteroinferior impingement were performed. The prevalence of MRI findings consistent with FAIM among this young population was 84.8% (95/112). The alpha angle was ≥55° in 77.7% (87/112) of hips, while the CEA was altered in 10.7% (12/112) of hips. Qualitative MRI findings consistent with FAIM were highly prevalent, and included loss of sphericity of the femoral head (77%), osseous bump (44%), femoral neck edema (21%), and acetabular osteitis (9%). The anterior impingement test was positive in 15% of the hips evaluated. Youth soccer players have a high prevalence of FAIM as diagnosed by MRI. There is no correlation between physical examination findings and MRI evidence of FAIM in this population.


#9 In-Season High-Intensity Interval Training Improves Conditioning In High School Soccer Players
Reference: Int J Exerc Sci. 2017 Sep 1;10(5):713-720. eCollection 2017.
Authors: Howard N, Stavrianeas S
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5609662/pdf/ijes-10-05-713.pdf
Summary: Soccer is characterized by high aerobic demands interspersed with frequent bursts of anaerobic activity. High-intensity interval training (HIIT) is considered a viable alternative to traditional endurance conditioning and offers the additional time-saving benefits of anaerobic training. We hypothesized that HIIT will compare favorably to traditional (aerobic-based) soccer conditioning over the course of a high school soccer season. Junior varsity soccer players were split into control (CON, n=16) and experimental (HIIT, n=16) groups for the 10-week study. The HIIT group performed 4-6 "all-out" sprints lasting 30s each, with 4.5 minute recovery, 3 times a week. The CON group performed endurance running for the same duration. The groups did not differ in any other aspect of their training. Participants completed the Yo-Yo intermittent recovery test level 1 (IR1), a 40-yard dash, vertical jump, Illinois agility test, and a sit-and-reach test, in two different testing sessions (pre/post season). Both HIIT and CON groups exhibited significant increase in IR1 test performance with time (741.6±307.6m vs. 1067.6±356.8m, p<.001 and 733.2±318.8m vs. 1165.2±252.8m, p<0.001 respectively), with no difference between groups. The CON group demonstrated a significant difference in the 40-yard dash over time (5.48±0.36s vs. 5.21±0.16s, p<0.004). While there was a difference in vertical jump between the pre and post tests for the HIIT group (42.20±7.04cm vs. 47.87±750cm respectively, p<0.019), no such effect was observed in the CON group. In contrast, there were differences in the agility test only for the CON group over time (16.67±0.76s vs. 16.15±0.49s, p<0.001). There were no differences in the flexibility test between groups. Our results indicate that HIIT offers similar endurance improvements to more traditional soccer training.

#10 Maturation-related adaptations in running speed in response to sprint training in youth soccer players
Reference: J Sci Med Sport. 2017 Sep 21. pii: S1440-2440(17)31058-7. doi: 10.1016/j.jsams.2017.09.012. [Epub ahead of print]
Authors: Moran J, Parry DA, Lewis I, Collison J, Rumpf MC, Sandercock GRH
Summary: This study investigated the effects of a previously recommended dose of sprint training (ST) in young male soccer players of differing maturity status. Male soccer players from two professional academies were divided into Pre-PHV (Training: n=12; Control: n=13) and Mid-PHV (Training: n=7; Control=10) groups. The training groups completed 16 sprints of 20m with 90s recovery, once per week. Between-group effect sizes (ES) were substantially larger in Pre-PHV (10m [1.54, CI: 0.74-2.23]; 20m [1.49, CI: 0.75-2.23]; 5-10-5 [0.92, CI: 0.23-1.61]) than in Mid-PHV (10m [-0.00, CI: -0.81 to 0.81]; 20m [-0.12, CI: -0.93 to 0.69]; 5-10-5 [-0.41, CI: -1.22 to 0.41]). Within-group effects demonstrated a similar, though less accentuated, trend which revealed ST to be effective in both Pre-PHV (10m [0.44, CI: -0.24 to 1.12]; 20m [0.45, CI: -0.23 to 1.13]; 5-10-5 [0.69, CI: 0.00-1.38]) and Mid-PHV (10m [0.51, CI: -0.38 to 1.40]; 20m [0.33, CI: -0.56 to 1.21]; 5-10-5 [0.43, CI: -0.46 to 1.32]). ST, in the amount of 16 sprints over 20m with a 90s rest, may be more effective in Pre-PHV youths than in Mid-PHV youths.


American Football
#1 National Football League Skilled and Unskilled Positions Vary in Opportunity and Yield in Return to Play After an Anterior Cruciate Ligament Injury
Reference: Orthop J Sports Med. 2017 Sep 21;5(9):2325967117729334. doi: 10.1177/2325967117729334. eCollection 2017 Sep.
Authors: Yang J, Hodax JD, Machan JT, Secrist ES, Durand WM, Owens BD, Eltorai AEM, Dodson CC
Summary: Anterior cruciate ligament (ACL) injuries pose a significant risk to the careers of players in the National Football League (NFL). The relationships between draft round and position on return to play (RTP) among NFL players are not well understood, and the ability to return to preinjury performance levels remains unknown for most positions. The purpose was to test for differences in RTP rates and changes in performance after an ACL injury by position and draft round. We hypothesized that skilled positions would return at a lower rate compared to unskilled positions. We further hypothesized that early draft-round status would relate to a greater rate of RTP and that skilled positions and a lower draft round would correlate with decreased performance for players who return to sport. Utilizing a previously established database of publicly available information regarding ACL tears among NFL players, athletes with ACL tears occurring between the 2010 and 2013 seasons were identified. Generalized linear models and Kaplan-Meier time-to-event models were used to test the study hypotheses. The overall RTP rate was 61.7%, with skilled players and unskilled players returning at rates of 64.1% and 60.4%, respectively (P = .74). Early draft-round players and unskilled late draft-round players had greater rates of RTP compared to skilled late draft-round players and both unskilled and skilled undrafted free agents (UDFAs). Skilled early draft-round players constituted the only cohort that played significantly fewer games after an injury. Unskilled UDFAs constituted the only cohort to show a significant increase in the number of games started and ratio of games started to games played, starting more games in which they played, after an injury. Early draft-round and unskilled players were more likely to return compared to their later draft-round and skilled peers. Skilled early draft-round players, who displayed relatively high rates of RTP, constituted the only cohort to show a decline in performance. Unskilled UDFAs, who exhibited relatively low rates of RTP, constituted the only cohort to show an increase in performance. The significant effect of draft round and position type on RTP may be caused by a combination of differences in talent levels and in opportunities given to returning to play.


#2 Recurrent Labral Tearing on Magnetic Resonance Imaging Is Not Predictive of Diminished Participation Among National Football League Athletes
Reference: Arthroscopy. 2017 Sep 30. pii: S0749-8063(17)30703-X. doi: 10.1016/j.arthro.2017.07.007. [Epub ahead of print]
Authors: Knapik DM, Gebhart JJ, Sheehan J, Tanenbaum JE, Salata MJ, Voos JE
Summary: The purpose was to investigate the prevalence of shoulder labral repair and utility of magnetic resonance imaging (MRI) in determining the risks of recurrent labral tearing and impact on future participation in the National Football League (NFL). Athletes invited to the NFL Combine between 2012 and 2015 were retrospectively reviewed. Athletes with a history of labral repair and MRI of the operative shoulder at the Combine were included in the study for further analysis, excluding athletes without a history of labral repair, labral repair without MRI at the Combine, additional procedure to the operative shoulder, or athletes still undergoing rehabilitation at the time of the Combine after labral repair. All MRIs were reviewed to determine initial labral repair location, the presence of recurrent tearing, and any concomitant shoulder pathology. Prospective information on future NFL participation in regard to draft status, games played, and games started in the athlete's first NFL season after the Combine was compared between athletes with a history of labral repair with and without recurrent tearing versus all other athletes participating in the Combine. A total of 132 (10.1%) athletes underwent 146 shoulder labral repair procedures before the NFL Combine, of whom 32% (n = 39 athletes, n = 46 shoulders) had recurrent labral tears on MRI. Athletes with recurrent tears were more likely to have undergone bilateral labral repairs (P = .048) and possess concomitant shoulder pathology (P < .001). Recurrent labral tearing was significantly more common in the posterior labrum in athletes with a history of posterior labral repairs (P = .032). Prospective participation in the NFL in terms of games played (P = .38) or started (P = .98) was not significantly reduced in athletes with a history of labral repair compared with those without repair. Participation was not diminished in athletes with recurrent labral tears compared with those with intact repairs or those with evidence of degenerative joint disease. Athletes invited to the NFL Scouting Combine with a history of bilateral repair, posterior labral repair, and concomitant shoulder pathology are at high risk of recurrent labral tearing on MRI. No significant reduction in NFL participation the year after the Combine was seen in athletes with a history of labral repair, recurrent labral tearing, or degenerative joint disease who were successfully drafted into the NFL. In athletes with a history of labral repair, assessment of labral integrity on MRI alone is not predictive of future short-term participation.

Wed

11

Oct

2017

Football is...(#24)

Football specific cutting maneuvers for muscular development.

Mon

09

Oct

2017

Football is...(#23)

Knee stability for movements.

Sun

08

Oct

2017

Football is...(#22)

Number of players affect intensity in SSG

Fri

06

Oct

2017

Football is...(#21)

Appropriate training load = performance + injury prevention

Wed

04

Oct

2017

Football is...(#20)

One option to train for keeping the ball in offensive 1 vs. 1.

Wed

04

Oct

2017

Latest research in football - week 39 - 2017

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 Resting metabolic rate of Indian Junior Soccer players: Testing agreement between measured versus selected predictive equations
Reference: Am J Hum Biol. 2017 Sep 30. doi: 10.1002/ajhb.23066. [Epub ahead of print]
Authors: Cherian KS, Shahkar F, Sainoji A, Balakrishna N, Yagnambhatt VR
Summary: Owing to a dearth of research related to Resting Metabolic Rate (RMR) among adolescent athletes in India, our study aimed to document RMR among junior soccer players (JSP) and to identify suitable RMR predictive models for JSP from nine existing equations. Forty Indian JSP (Boys = 21, Girls = 19) representing the under-12 and under-16 age categories were assessed for body composition (skinfold technique) and RMR (oxycon mobile). Two-way ANOVA and ANCOVA were used to examine the differences across age and sex. Bland-Altman plot was used to test agreement between measured vs. predicted RMR using the equations of Cunningham (, The American Journal of Clinical Nutrition, 33), Soares et al. (, European Journal of Clinical Nutrition, 47; 1998, British Journal of Nutrition, 79), Henry (, Public Health Nutrition, 8), and Patil and Bharadwaj (, Journal of Postgraduate Medicine, 59) for non-athletic populations and the equations of De Lorenzo et al. (, The Journal of Sports Medicine and Physical Fitness, 39), Wong et al. (, Singapore Medical Journal, 53), and ten Haaf & Weijs (, PloS One, 9) for adult athletes. RMR showed significant (P < .01) sex differences (Boys: 1343 ± 297.1; Girls: 1135 ± 116.7 kcal·day-1 ). While RMR values adjusted for fat-free mass (FFM) were similar across age and sex. The equation of Soares et al. (, British Journal of Nutrition, 79) for girls and Wong et al. (, Singapore Medical Journal, 53) for boys showed better RMR predictability. FFM explained variation in RMR across age and sex. The FFM-based Soares et al. (, British Journal of Nutrition, 79) equation for girls and body weight-based Wong et al. (, Singapore Medical Journal, 53) equation for boys are best suited for predicting RMR


#2 Effects of age on the soccer-specific cognitive-motor performance of elite young soccer players: Comparison between objective measurements and coaches' evaluation
Reference: PLoS One. 2017 Sep 27;12(9):e0185460. doi: 10.1371/journal.pone.0185460. eCollection 2017.
Authors: Hicheur H, Chauvin A, Chassot S, Cheneviere X, Taube W
Download link: http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0185460&type=printable
Summary: The cognitive-motor performance (CMP), defined here as the capacity to rapidly use sensory information and transfer it into efficient motor output, represents a major contributor to performance in almost all sports, including soccer. Here, we used a high-technology system (COGNIFOOT) which combines a visual environment simulator fully synchronized with a motion capture system. This system allowed us to measure objective real-time CMP parameters (passing accuracy/speed and response times) in a large turf-artificial grass playfield. Forty-six (46) young elite soccer players (including 2 female players) aged between 11 and 16 years who belonged to the same youth soccer academy were tested. Each player had to pass the ball as fast and as accurately as possible towards visual targets projected onto a large screen located 5.32 meters in front of him (a short pass situation). We observed a linear age-related increase in the CMP: the passing accuracy, speed and reactiveness of players improved by 4 centimeters, 2.3 km/h and 30 milliseconds per year of age, respectively. These data were converted into 5 point-scales and compared to the judgement of expert coaches, who also used a 5 point-scale to evaluate the same CMP parameters but based on their experience with the players during games and training. The objectively-measured age-related CMP changes were also observed in expert coaches' judgments although these were more variable across coaches and age categories. This demonstrates that high-technology systems like COGNIFOOT can be used in complement to traditional approaches of talent identification and to objectively monitor the progress of soccer players throughout a cognitive-motor training cycle.


#3 Comparison of Thigh Muscle Strain Occurrence and Injury Patterns between Male and Female High School Soccer-Athletes
Reference: J Sport Rehabil. 2017 Sep 27:1-35. doi: 10.1123/jsr.2016-0178. [Epub ahead of print]
Authors: Cross KM, Gurka KK, Saliba S, Conaway M, Hertel J
Summary: Thigh muscles strains are among the most common injuries in high school soccer for both males and females. Similar results have been reported among collegiate soccer players, specifically for hamstring strains. In collegiate soccer, males have a higher injury rate than women although they share common injury characteristics. Currently, no studies exist comparing the injury rate or injury characteristics of thigh muscle strains between sexes playing high school soccer. The objective of the study was to compare thigh muscle strain injury rates and injury event characteristics among sexes participating in high school soccer. High school soccer athletes who had a thigh muscle strain were involved in this study. Injury rates of thigh muscle strains were calculated between sexes. The occurrence of the following variables during a thigh muscle injury were compared between sexes: grade level, age, level of play, event type, time of practice, time of competition, basic injury mechanism, soccer activity, player position, field location, practice type, time of season. Males had a lower injury rate of thigh muscle strains during competition than females. (RR=0.66; 95% CI, 0.47, 0.93) No differences between sexes existed in the distribution of first-time or recurrent event characteristics. When combining sexes, recurrent strains (93%) occurred more frequently on the offensive side of the field than first-time strains (59%), P<0.0001. The majority of strains occurred among the varsity players (71%), during running activities (60%) and during practices (58%). Males were less likely to sustain a thigh muscle strain during competitions, but no other differences existed between sexes. The events surrounding all thigh muscle strains may be described with some common properties. Consideration of these characteristics may assist in the development of preventive and rehabilitative programs as well as direct future research on thigh muscle strains among high school soccer players.


#4 Locomotor and Heart Rate Responses of Floaters During Small-Sided Games in Elite Soccer Players: Effect of Pitch Size and Inclusion of Goal Keepers
Reference: Int J Sports Physiol Perform. 2017 Sep 27:1-13. doi: 10.1123/ijspp.2017-0340. [Epub ahead of print]
Authors: Lacome M, Simpson BM, Cholley Y, Buchheit M
Summary: The purpose was to (1) compare the locomotor and heart rate responses between floaters and regular players during both small and large small sided games (SSGs) and (2) examine whether the type of game (i.e., game simulation vs possession game) affects the magnitude of the difference between floaters and regular players. Data were collected in 41 players belonging to an elite French football team during three consecutive seasons (2014-2017). 5-Hz GPS were used to collect all training data, with the Athletic Data Innovation analyser (v5.4.1.514, Sydney, Australia) used to derive total distance (m), high-speed distance (> 14.4 km.h-1, m) and external mechanical load (MechL, a.u). All SSGs included exclusively one floater, and were divided into two main categories, according to the participation of goal-keepers (GK) (game simulation, GS) or not (possession games, PO) and then further divided into small and large (>100 m2/player) SSGs based on the area per player ratio. Locomotor activity and mechanical load performed were likely-to-most likely lower (moderate to large magnitude) in floaters compared with regular players, while differences in HR responses were unclear to possibly higher (small) in floaters. The magnitude of the difference in locomotor activity and MechL between floaters and regular players was substantially greater during GS compared with PO. Compared with regular players, floaters present decreased external load (both locomotor and MechL) despite unclear to possibly slightly higher HR responses during SSGs. Moreover, the responses of floaters compared with regular players are not consistent across different sizes of SSGs, with greater differences during GS than PO.


#5 Successful return to play following adductor longus proximal tendon rupture in professional soccer without re-injury at 12 months: A case report
Reference: J Back Musculoskelet Rehabil. 2017 Sep 8. doi: 10.3233/BMR-170857. [Epub ahead of print]
Authors: Gozubuyuk OB, Moen MH, Akman M, Ipseftel I, Karakuzu A
Summary: Treatment of total ruptures of adductor longus is challenging in professional sports. Time for return to pre-injury level as well as re-injury rates are of concern and surgical and conservative treatment approaches are debated; yet no consensus approach described for professional athletes. We present a case of a professional soccer player who experienced a rupture in his left adductor longus proximal tendon during a game and was treated conservatively. This case was followed-up during clinical assessment, imaging and strength testing until and after return to play. Primary outcome measure was the return to standard play condition at his pre-injury level without any functional deficits, measured by isokinetic testing. Second outcome measure was the recurrence. No recurrence was observed during the first year of follow-up. Total ruptures are very challenging for both the physician and the player to make a quick decision due to minimal or lack of pain. Functional outcomes are almost identical although operative treatments need longer time to return to play. This case report adds another example to the literature of a successful return to play after non-operative treatment of adductor longus rupture at elite level soccer.


#6 Is strength-training frequency a key factor to develop performance adaptations in young elite soccer players?
Reference: Eur J Sport Sci. 2017 Sep 24:1-11. doi: 10.1080/17461391.2017.1378372. [Epub ahead of print]
Authors: Otero-Esquina C, de Hoyo Lora M, Gonzalo-Skok O, Dominguez-Cobo S, Sanchez H
Summary: The aim of this study was to analyse the effects of a combined strength-training programme (full-back squat, YoYoTM leg curl, plyometrics and sled towing exercises) on performance in elite young soccer players and to examine the effects when this training programme was performed one or two days per week. Thirty-six male soccer players (U-17 to U-19) were recruited and assigned to experimental groups (EXP1: 1 s w-1; EXP2: 2 s w-1) or a control group (CON). Performance was assessed through a countermovement jump (CMJ) test (relative peak power [CMJPP] and CMJ height [CMJH]), a 20-m linear sprint test with split-times at 10-m, and a change of direction test (V-cut test) 1 week before starting the training programme and also 1 week after performing such training programme. Within-group analysis showed substantial improvements in CMJ variables (ES: 0.39-0.81) and COD (ES: 0.70 and 0.76) in EXP1 and EXP2, while EXP2 also showed substantial enhancements in all linear sprinting tests (ES: 0.43-0.52). Between-group analysis showed substantially greater improvements in CMJ variables (ES: 0.39-0.68) in experimental groups in comparison to CON. Furthermore, EXP2 achieved a substantial better performance in 20-m (ES: 0.48-0.64) than EXP1 and CON. Finally, EXP2 also showed greater enhancements in 10-m (ES: 0.50) and V-cut test (ES: 0.52) than EXP1. In conclusion, the combined strength-training programme improved jumping ability, independently of training frequency, though the achievement of two sessions per week also enhanced sprinting abilities (linear and COD) in young soccer players.


#7 Neuromuscular responses and physiological patterns during a soccer simulation protocol. Artificial turf versus natural grass
Reference: J Sports Med Phys Fitness. 2017 Sep 22. doi: 10.23736/S0022-4707.17.07768-4. [Epub ahead of print]
Authors: Lopez-Fernandez J, Garcia-Unanue J, Sanchez-Sanchez J, Leon M, Hernando E, Gallardo L
Summary: Latest studies suggest similar performance of soccer players either on artificial turf (AT) or natural grass (NG). However, it is not clear if their muscular and physiological responses are also similar on both surfaces. This research aims to assess the influence of game surface on physiological patterns and neuromuscular responses of soccer players during a soccer simulation protocol (SSP) that incorporates repeated sprints and nonlinear actions at maximum speed. Sixteen amateur soccer players completed three bouts of the SSP on both AT and NG. The mechanical behaviour of both surfaces was recorded and the order was randomly established for each player. The physiological responses were measured during the SSP. A contra-movement jump and a tensiomyography analysis of the rectus femurs (RF) and biceps femoris (BF) were assessed right before and right after the SSP. Both surfaces presented different mechanical properties. No differences among either surfaces or bouts were found for heart rate (HR) peak and HR mean (p >0.05). While the half-relaxation time of the RF on NG decreased after the SSP (right-leg:-44.430 ms; p = 0.049; left-leg: -52.131 ms; p = 0.008), the sustain time of the BF decreased after the SSP on AT (right-leg: +64.868 ms; p = 0.007; left-leg: +87.564 ms; p<0.001). No differences between surfaces were found for the contra-movement jump. The mechanical behaviour of both surfaces does not differ enough to cause different physiological and neuromuscular responses. Playing on AT should cause similar neuromuscular responses to NG.


#8 Variability of GPS-derived running performance during official matches in elite professional soccer players
Reference: J Sports Med Phys Fitness. 2017 Sep 22. doi: 10.23736/S0022-4707.17.07500-4. [Epub ahead of print]
Authors: Al Haddad H, Mendez-Villanueva A, Torreno N, Munguia-Izquierdo D, Suarez-Arrones L
Summary: The aim of this study was to assess the match-to-match variability obtained using GPS devices, collected during official games in professional soccer players. GPS-derived data from nineteen elite soccer players were collected over two consecutive seasons. Time-motion data for players with more than five full-match were analyzed (n=202). Total distance covered (TD), TD >13-18 km/h, TD >18-21 km/h, TD >21 km/h, number of acceleration >2.5-4 m.s-2 and >4 m.s-2 were calculated. The match-to-match variation in running activity was assessed by the typical error expressed as a coefficient of variation (CV,%) and the magnitude of the CV was calculated (effect size). When all players were pooled together, CVs ranged from 5% to 77% (first half) and from 5% to 90% (second half), for TD and number of acceleration >4 m.s-2, and the magnitude of the CVs were rated from small to moderate (effect size = 0.57-0.98). The CVs were likely to increase with running/acceleration intensity, and were likely to differ between playing positions (e.g., TD > 13-18 km/h 3.4% for second strikers vs 14.2% for strikers and 14.9% for wide-defenders vs 9.7% for wide-midfielders). Present findings indicate that variability in players' running performance is high in some variables and likely position-dependent. Such variability should be taken into account when using these variables to prescribe and/or monitor training intensity/load. GPS-derived match-to-match variability in official games' locomotor performance of professional soccer players is high in some variables, particularly for high-speed running, due to the complexity of match running performance and its most influential factors and reliability of the devices.


#9 Adding a post-training FIFA 11+ exercise program to the pre-training FIFA 11+ injury prevention program reduces injury rates among male amateur soccer players: a cluster-randomised trial
Reference: J Physiother. 2017 Sep 20. pii: S1836-9553(17)30102-9. doi: 10.1016/j.jphys.2017.08.004. [Epub ahead of print]
Authors: Al Attar WSA, Soomro N, Pappas E, Sinclair PJ, Sanders RH
Download link: http://www.journalofphysiotherapy.com/article/S1836-9553(17)30102-9/pdf
Summary: Does adding a post-training Fédération Internationale de Football Association (FIFA) 11+ exercise program to the pre-training FIFA 11+ injury prevention program reduce injury rates among male amateur soccer players? Twenty-one teams of male amateur soccer players aged 14 to 35 years were randomly assigned to the experimental group (n=10 teams, 160 players) or the control group (n=11 teams, 184 players). Both groups performed pre-training FIFA 11+ exercises for 20minutes. The experimental group also performed post-training FIFA 11+ exercises for 10minutes. The primary outcomes measures were incidence of overall injury, incidence of initial and recurrent injury, and injury severity. The secondary outcome measure was compliance to the experimental intervention (pre and post FIFA 11+ program) and the control intervention (pre FIFA 11+ program). During one season, 26 injuries (team mean=0.081 injuries/1000 exposure hours, SD=0.064) were reported in the experimental group, and 82 injuries were reported in the control group (team mean=0.324 injuries/1000hours, SD=0.084). Generalised Estimating Equations were applied with an intention-to-treat analysis. The pre and post FIFA 11+ program reduced the total number of injuries (χ2 (1)=11.549, p=0.001) and the incidence of initial injury (χ2 (2)=8.987, p=0.003) significantly more than the pre FIFA 11+ program alone. However, the odds of suffering a recurrent injury were not different between the two groups (χ2 (1)=2.350, p=0.125). Moreover, the severity level of injuries was not dependent upon whether or not the pre and post FIFA 11+ program was implemented (χ2 (1)=0.016, p=0.898). Implementation of the FIFA 11+ program pre-training and post-training reduced overall injury rates in male amateur soccer players more than the pre FIFA 11+ program alone.


#10 Symptoms of common mental disorders and related stressors in Danish professional football and handball
Reference: Eur J Sport Sci. 2017 Sep 29:1-7. doi: 10.1080/17461391.2017.1381768. [Epub ahead of print]
Authors: Kilic O, Aoki H, Haagensen R, Jensen C, Johnson U, Kerkhoffs GMMJ, Gouttebarge V
Summary: The aim of the study was twofold, namely (i) to determine the prevalence of symptoms of common mental disorders (CMDs) among current and retired professional football and handball players and (ii) to explore the relationship of psychosocial stressors with the outcome measures under study. A total of 1155 players were enrolled in an observational study based on a cross-sectional design. Questionnaires based on validated scales were set up and distributed among current and retired professional football and handball players by the Danish football and handball players' union. In professional football, the highest prevalence (4 weeks) of symptoms of CMDs was 18% and 19% for anxiety/depression among current and retired players, respectively. In professional handball, the highest prevalence (4 weeks) of symptoms of CMDs was 26% and 16% for anxiety/depression among current and retired players, respectively. For both the current and retired professional football and handball players, a higher number of severe injuries and recent adverse life events (LE) were related to the presence of symptoms of CMD. Players exposed to severe injuries and/or recent adverse LE were 20-50% times more likely to report symptoms of CMD. The results suggest that it is possible to recognize the population of professional athletes that are more likely to develop symptoms of CMD. This could create the opportunity to intervene preventively on athletes that suffered from severe injury and/or recent adverse LE that could lead to a faster and safer recovery and psychological readiness to return to play.


American Football
#1 Evaluating behavioral skills training to teach safe tackling skills to youth football players
Reference:  J Appl Behav Anal. 2017 Sep 20. doi: 10.1002/jaba.412. [Epub ahead of print]
Authors: Tai SSM, Miltenberger RG
Summary: With concussion rates on the rise for football players, there is a need for further research to increase skills and decrease injuries. Behavioral skills training is effective in teaching a wide variety of skills but has yet to be studied in the sports setting. We evaluated behavioral skills training to teach safer tackling techniques to six participants from a Pop Warner football team. Safer tackling techniques increased during practice and generalized to games for the two participants who had opportunities to tackle in games.


#2 Return to play after shoulder instability in National Football League athletes
Reference: J Shoulder Elbow Surg. 2017 Sep 20. pii: S1058-2746(17)30448-2. doi: 10.1016/j.jse.2017.07.027. [Epub ahead of print]
Authors: Okoroha KR, Taylor KA, Marshall NE, Keller RA, Fidai M, Mahan MC, Varma V, Moutzouros V
Summary: We hypothesized that National Football League (NFL) players sustaining a shoulder destabilizing injury could return to play (RTP) successfully at a high rate regardless of treatment type. We identified and evaluated 83 NFL players who sustained an in-season shoulder instability event while playing in the NFL. NFL RTP, incidence of surgery, time to RTP, recurrent instability events, seasons/games played after the injury, and demographic data were collected. Overall RTP was determined, and players who did and did not undergo operative repair were compared. Ninety-two percent of NFL players returned to NFL regular season play at a median of 0.0 weeks in those sustaining a shoulder subluxation and 3.0 weeks in those sustaining a dislocation who did not undergo surgical repair (P = .029). Players who underwent operative repair returned to play at a median of 39.3 weeks. Forty-seven percent of players had a recurrent instability event. For players who were able to RTP, those who underwent surgical repair (31%) had a lower recurrence rate (26% vs. 55%, P = .021) and longer interval between a recurrent instability event after RTP (14.7 vs. 2.5 weeks, P = .050). There is a high rate of RTP after shoulder instability events in NFL players. Players who sustain shoulder subluxations RTP faster but are more likely to experience recurrent instability than those with shoulder dislocations. Surgical stabilization of the shoulder after an instability event decreases the chances of a second instability event and affords a player a greater interval between the initial injury and a recurrent event.


#3 Concussion Nondisclosure During Professional Career Among a Cohort of Former National Football League Athletes
Reference: Am J Sports Med. 2017 Sep 1:363546517728264. doi: 10.1177/0363546517728264. [Epub ahead of print]
Authors: Kerr ZY, Register-Mihalik JK, Kay MC, DeFreese JD, Marshall SW, Guskiewicz KM
Summary: Despite a focus on the incidence and effects of concussion, nondisclosure of sports-related concussions among retired players from the National Football League (NFL) has yet to be examined. The purpose was to examine the prevalence of and factors associated with nondisclosure of sports-related concussions in former NFL athletes. A sample of 829 former NFL players completed a general health survey. This historical cohort included players who had played before World War II to 2001. Respondents retrospectively recalled sports-related concussions that they sustained during their professional careers and whether at least one of these sports-related concussions was not reported to medical staff. We computed the prevalence of nondisclosure among those recalling sport-related concussions during their professional careers. Multivariable binomial regression estimated adjusted prevalence ratios (PR) with 95% confidence intervals (CIs) controlling for race/ethnicity, number of years played, primary position played, professional career concussion history, and playing era. Playing era was categorized by whether the majority of a player's career was before or after a 1976 rule change to limit contact ("spearing"). Overall, 417 (50.3%) respondents reported they had sustained a concussion and did not inform medical staff at least once during their professional playing career. Nonwhite respondents had a higher prevalence of nondisclosure than white/non-Hispanic respondents (adjusted PR = 1.19; 95% CI, 1.02-1.38). An interaction between professional career concussion history and playing era was also found ( P = .08). Compared with those in the pre-spearing rule change group with 1 or 2 concussions, all other groups had larger prevalences of nondisclosure (increases ranging from 41% to 153% in multivariable models). Across concussion strata, nondisclosure prevalence was generally higher in the post-spearing rule change group than the pre-spearing rule change group, with the largest differences found among those with 1 or 2 concussions or those with 3 or 4 concussions. A large proportion of former NFL players in this historical cohort reported at least one instance of not disclosing sports-related concussions to medical staff. Future research on concussion nondisclosure needs to identify mechanisms to improve football players' intentions to disclose concussion-related symptoms to health care providers and to equip health care providers with more effective strategies for timely identification of concussion.


#5 A Narrative Review of the Physical Demands and Injury Incidence in American Football: Application of Current Knowledge and Practices in Workload Management
Reference: Sports Med. 2017 Sep 25. doi: 10.1007/s40279-017-0783-2. [Epub ahead of print]
Authors: Edwards T, Spiteri T, Piggott B, Haff GG, Joyce C
Summary: The sport of American football (AmF) exposes athletes to high-velocity movements and frequent collisions during competition and training, placing them at risk of contact and non-contact injury. Due to the combative nature of the game, the majority of injuries are caused by player contact; however, a significant number are also non-contact soft-tissue injuries. The literature suggests that this mechanism of injury can be prevented through workload monitoring and management. The recent introduction of microtechnology into AmF allows practitioners and coaches to quantify the external workload of training and competition to further understand the demands of the sport. Significant workload differences exist between positions during training and competition; coupling this with large differences in anthropometric and physical characteristics between and within positions suggests that the training response and physiological adaptations will be highly individual. Effective athlete monitoring and management allows practitioners and coaches to identify how athletes are coping with the prescribed training load and, subsequently, if they are prepared for competition. Several evidence-based principles exist that can be adapted and applied to AmF and could decrease the risk of injury and optimise athletic performance.


#6 The Epidemiology of Overuse Conditions in Youth Football and High School Football Players
Reference: J Athl Train. 2017 Sep 26. doi: 10.4085/1062-6050-52.10.04. [Epub ahead of print]
Authors: Morris K, Simon J, Grooms DR, Starkey C, Dompier TP, Kerr ZY
Summary: High-intensity sport training at the youth level has led to increased concern for overuse conditions. Few researchers have examined overuse conditions in youth sports. The purpose was to examine the rates, risks, and distributions of overuse conditions between youth and high school football. The Youth Football Safety Study (YFSS) investigated youth football athletes from age 5 to 14 years. The National Athletic Treatment, Injury and Outcomes Network (NATION) focused on high school football athletes 14 to 18 years old. The YFSS data consisted of 210 team-seasons, and the NATION data consisted of 138 team-seasons. Athletic trainers collected football injury and exposure data during the 2012 and 2013 seasons. Injury rates, risks, and distributions were calculated, with injury rate ratios, risk ratios, and injury proportion ratios with 95% confidence intervals (CIs) comparing high school and youth football players. The YFSS reported 1488 injuries, of which 53 (3.6%) were overuse conditions. The NATION reported 12 013 injuries, of which 339 (2.8%) were overuse conditions. The overuse condition rate did not differ between high school and youth football (3.93 versus 3.72/10 000 athlete exposures; injury rate ratio = 1.06; 95% CI = 0.79, 1.41). However, the 1-season risk of overuse condition was higher in high school than in youth football players (2.66% versus 1.05%; risk ratio = 2.53; 95% CI = 1.84, 3.47). Compared with high school football players, youth football players had greater proportions of overuse conditions that were nontime loss (ie, <24 hours participation-restriction time; 83.0% versus 67.0%; injury proportion ratio = 1.24; 95% CI = 1.07, 1.43) and affecting the lower extremity (92.5% versus 62.5%; injury proportion ratio = 1.48; 95% CI = 1.32, 1.65). Overuse conditions may not present a primary concern in youth and high school football players. However, differences existed between the 2 levels of competition. Although additional research on the incidence of overuse conditions across all youth and high school sports is needed, these findings may highlight the need for programming that is specific to competition level.


#7 Characteristics and Outcomes of Arthroscopic Femoroacetabular Impingement Surgery in the National Football League
Reference: Am J Sports Med. 2017 Sep 1:363546517729163. doi: 10.1177/0363546517729163. [Epub ahead of print]
Authors: Nwachukwu BU, Bedi A, Premkumar A, Draovitch P, Kelly BT
Summary: Previous studies have reported that hip abnormalities may account for 10% of injuries in professional football players. The effect of femoroacetabular impingement (FAI) and arthroscopic FAI surgery in National Football League (NFL) athletes has not been well studied. The purpose was to investigate the effect of arthroscopic FAI surgery on return to play (RTP) and RTP performance in NFL players. NFL athletes undergoing arthroscopic FAI surgery at a single institution between 2006 and 2014 were identified. Medical records were reviewed for demographic, clinical, and operative variables. RTP and RTP performance were assessed based on a review of publicly available NFL player statistics. RTP and RTP performance data included time to RTP; games played before and after the injury; yearly total yards and touchdowns for offensive players; and yearly total tackles, sacks, and interceptions for defensive players. The offensive power rating (OPR = [total yards/10] + [total touchdowns × 6]) and defensive power rating (DPR = total tackles + [total sacks × 2] + [total interceptions × 2]) were calculated. Paired t tests comparing preinjury and postinjury seasons were performed. A matched cohort of NFL players was created to compare trends for OPR, DPR, and career longevity. Forty-eight hips in 40 NFL players (mean age, 25.6 years) with symptomatic FAI were included; 8 players underwent staged bilateral hip arthroscopic procedures. The majority of players were offensive (n = 24; 60.0%), with offensive lineman (n = 11; 27.5%) being the most common of all positions. Of the 48 included hips, all had labral tears, and 41 (85.4%) underwent labral repair. Forty-two of the 48 hips (87.5%) underwent cam decompression, and 10 (20.8%) underwent rim decompression. Of the 40 included players, 37 (92.5%) achieved RTP to professional competition after their hip arthroscopic surgery at a mean of 6.0 months. Before the injury, included patients played in a mean of 11.0 games compared with 9.5 games in their postoperative season ( P = .26). The mean OPR and DPR demonstrated a nonsignificant decline in the postoperative season (preinjury OPR, 40.2; postinjury OPR, 32.3; P = .34) (preinjury DPR, 49.6; postinjury DPR, 36.4; P = .10). A similar decline in the OPR and DPR across seasons was observed in the control group. NFL athletes played, on average, 3.3 ± 1.5 seasons after undergoing hip arthroscopic surgery; this was not significantly different from the controls (2.5 ± 1.5 seasons; P = .47). There was no significant difference in mean annual salaries based on contracts negotiated before the injury and the first negotiated contract after surgery ($3.3 million vs $3.6 million, respectively; P = .58). There was a very high rate of RTP in the NFL after arthroscopic FAI surgery; this rate is higher than what has been previously reported for other orthopaedic procedures in NFL athletes. Additionally, these NFL athletes achieved RTP at a faster time frame (6 months) than previously reported for other procedures. These findings have important implications for counseling elite football players about the expected outcome of arthroscopic FAI surgery.


#8 Daily Fantasy Football and Self-Reported Problem Behavior in the United States
Reference: J Gambl Stud. 2017 Sep 26. doi: 10.1007/s10899-017-9720-4. [Epub ahead of print]
Authors: Dwyer B, Shapiro SL, Drayer J
Summary: Traditional, season-long fantasy sport participation has grown considerably since the late 1990s, and in an attempt to capitalize on this growing demand, daily fantasy sports (DFS) providers have created a new game where money changes hands instantly. This change has led some legal commentators and state agencies to believe the game is a form of Internet gambling similar to online poker, blackjack, and sports wagering, and thus, it requires increased regulation or even prohibition. Little is known, however, about the gambling behavior associated with DFS participation. Thus, the purpose of the current study was to examine problem gambling severity in conjunction with DFS participant motives, perceptions, and consumption behavior. Over 500 DFS participants were surveyed, and the results suggest DFS participants behave similarly with participants in other forms of gambling activities. In addition, the findings suggest additional consumer protections may be needed to prevent further problem behavior such as chasing.


#9 Lifetime Prevalence of Injuries in Incoming Division I Collegiate Football Players
Reference: Phys Sportsmed. 2017 Sep 27. doi: 10.1080/00913847.2017.1386068. [Epub ahead of print]
Authors: Sarac N, Haynes W, Pedroza A, Kaeding C, Borchers J
Summary: The purpose of this study is to determine the lifetime prevalence of past injuries in incoming first year football players in a Division 1 college football team. Pre-participation questionnaires from 605 first-year football players over 20 years (1996-2015) were examined to determine the prevalence of concussions, stingers, fractures, and musculoskeletal surgeries sustained before playing at the collegiate level. Players were grouped by position: wide receiver and defensive back (WR/DB), offensive and defensive linemen (OL/DL), all other positions (OP), and unknown (UKN). Prevalence of injuries by year and position was compared using Pearson's χ2 Test (p<0.05). The reported lifetime prevalence is as follows: concussion (21%), stinger (23%), musculoskeletal surgery (23%), and fracture (44%). There were no significant differences in lifetime prevalence of concussions (p=0.49), stingers (p=0.31), fractures (p=0.60), or musculoskeletal surgeries (p=0.97) based on position. There were also no significant differences in the lifetime prevalence of concussions (p=0.14), musculoskeletal surgeries (p=0.50), or fractures (p=0.59) based on year. However, there was a significant difference in the lifetime prevalence of stingers based on year (p<0.001). There was an expectation to observe an increase in injury prevalence by entering year, but this was not seen. A decrease in stingers was actually observed, but there was no significant difference among any other injury recorded. These results do not support the perception that football injuries are on the rise. Under reporting is a significant concern as players may fear disqualification or that they are evaluated by the coaching staff based on their medical history. More research is needed to confirm lifetime injury prevalence and evaluate differences over time among football players.


#10 Distal Fibula Fractures in National Football League Athletes
Reference: Orthop J Sports Med. 2017 Sep 8;5(9):2325967117726515. doi: 10.1177/2325967117726515. eCollection 2017 Sep.
Authors: Werner BC, Mack C, Franke K, Barnes RP, Warren RF, Rodeo SA
Summary: Despite the frequency of distal fibula fractures in elite athletes and the significant potential impact on the athletes' season and future careers, little data exist characterizing the epidemiology of these injuries or, more importantly, return to competition. The purpose was to (1) evaluate the incidence of acute distal fibula fractures in National Football League (NFL) athletes, including isolated distal fibula and combined ankle fracture patterns; (2) analyze distal fibula fracture rates in NFL athletes by position, type of play, and contact type; (3) determine the rates of distal fibula fracture surgery in NFL athletes; and (4) report the days missed due to distal fibula fractures in NFL athletes. A retrospective review of distal fibula fractures reported to the NFL from 2000 to 2014 was performed using the NFL Injury Surveillance System. All distal fibula fractures were included, along with isolated and combined fracture patterns. Stress fractures and proximal fibula fractures were excluded. Epidemiological data and rates of surgery were determined. Return to sport was calculated and stratified by injury pattern and management. Overall, 237 distal fibula fractures in NFL athletes from 2000 to 2014 were included; 197 (83%) were isolated distal fibula fractures. A mean of 16 distal fibula fractures occurred each year (median, 16 per year). Fractures occurred most frequently on running (38%) and passing (24%) plays, but the frequency was next highest on kickoffs (16%), despite the relative infrequency of kickoffs during the average game compared with other play types. Surgery was reported for more than half of all distal fibula fractures (n = 128, 54%). Overall, patients who underwent surgery missed significantly more days (mean, 123.8 days) than players who did not undergo surgery (mean, 75.3 days) (P < .001). Players with isolated distal fibula fractures had significantly fewer days missed (mean, 93.6 days) compared with those with combined patterns (mean, 132.3 days) (P = .0004). Fibula fractures affect a number of NFL athletes and result in significant time missed from competition. Further research is required to determine the optimal management of fibula fractures in NFL athletes. In this study, time to return to play depended on both the fracture pattern and whether surgery was required and ranged from 72 to 145 days.

Tue

03

Oct

2017

Football is...(#19)

Youth players - every Training session 1.000 touches!

Mon

02

Oct

2017

Football...(#18)

Dynamic stretches done correctly are important during the warm-up.

Mon

02

Oct

2017

German Society of Sport Science - Section Football

The German Sport Science Association – Section Football had its annual meeting at Ruhr University Bochum from 28.-30.9.2017.

I attended the conference and the important slides from the one and only english presentation from the one and only Aaron Coutts about “Developing athlete monitoring systems for football: theoretical foundations” are shown below.

Thu

28

Sep

2017

Football is...(#17)

Attacking third entry is crucial for scoring goals.

Thu

28

Sep

2017

Latest research in football - week 38 - 2017

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 Elite Youth Soccer Players' Physiological Responses, Time-Motion Characteristics, and Game Performance in 4 vs. 4 Small-Sided Games: The Influence of Coach Feedback
Reference: J Strength Cond Res. 2017 Oct;31(10):2652-2658. doi: 10.1519/JSC.0000000000001717.
Authors: Brandes M, Elvers S
Summary: The purpose of this study was to determine the impact of mild vs. strongly pushed coach feedback on the physiological response, ratio of perceived exertion (RPE), and time-motion characteristics in soccer training with small-sided games (SSGs). Sixteen elite youth soccer players (aged 17.2 ± 0.7 years, V[Combining Dot Above]O2max 62.1 ± 3.8 ml·kg·min) played two 4 vs. 4 small-sided games each. In random order, the coach provided a mild, unobtrusive, or a strongly pushed feedback throughout the game. Physiological measurements included heart rate expressed in mean values and intensity zones, blood lactate concentration, and RPE. The distance traveled, number of sprints, and work:rest ratio were captured by global positioning systems at 5 Hz. Game performance, such as volume of play and efficacy index, was estimated using the Team Sports Assessment Procedure. No differences were found for the physiological response and time-motion characteristics, but effect sizes demonstrated an increase in RPE (+0.4, p = 0.27) and a decrease in game performance (e.g., volume of play, -2.5, p = 0.08) under pushed feedback. Although a pushed feedback raises RPE, it negatively affected the players' game performance, without necessarily provoking higher physiological responses. These results should help coaches to understand that modifying the type of feedback provided during SSG does not impact the physiological response if SSG are already played with high intensity but that the feedback affects RPE and game performance. To keep a better game performance, soccer coaches are encouraged to provide smooth feedback during SSG.


#2 Hopping and Landing Performance in Male Youth Soccer Players: Effects of Age and Maturation
Reference: Int J Sports Med. 2017 Sep 20. doi: 10.1055/s-0043-114009. [Epub ahead of print]
Authors: Read PJ, Oliver JL, Myer G, De Ste Croix M, Lloyd R
Summary: Quantifying hopping and landing performances can assist coaches in identifying young male soccer players who may be at increased risk of injury. The influence of chronological age and maturation on these measures in this population is unknown. Single leg hop for distance (SLHD) and 75% horizontal hop and stick landing force (75%Hop) were examined in a cross-sectional sample (N=400) of elite male youth soccer players. Between-group differences for both chronological age (U11-U18) and stage of maturation (pre-, circa- or post-peak height velocity (PHV)) were analyzed. Absolute 75%Hop increased with both age and maturation. Apart from the U18s, pre-PHV and U11-U12 players displayed the greatest relative landing forces compared to all other groups (p<0.001; d=0.56-0.93). Absolute and relative SLHD were greatest in the U18s and post-PHV players (p<0.001; d=0.35-2.04). A trend showed increased SLHD with each consecutive age group although a reduction in performance was identified in the U13s (d=0.50-0.59). High volumes of accumulated soccer participation in the U18s may lead to altered landing strategies indicative of high injury risk. A temporary reduction in hop performance in the U13s may also be linked to a period of adolescent awkwardness.


#3 Case study: sleep and injury in elite soccer. A mixed method approach
Reference: J Strength Cond Res. 2017 Sep 11. doi: 10.1519/JSC.0000000000002251. [Epub ahead of print]
Authors: Nedelec M, Leduc C, Dawson B, Guilhem G, Dupont G.
Summary: The present case study allowed an examination of the link between sleep and injury occurrence in an elite male soccer player competing in French League 1 and Union of European Football Associations matches. During 4 months, a mixed method approach was used, combining actigraphic sleep assessment with qualitative interviews on a daily basis. Three injuries were reported over the study period. Sleep onset latency, both in the single night (117±43 min) and in the week (78±50 min) before injury occurrence, was longer than pre-season baseline values (18±13 min; effect size (ES): 3.1 and 1.6, respectively). Similarly, sleep efficiency in the single night (73±7%) and the week (75±7%) before injury occurrence, was lower than baseline (90±3%; ES: 3.2 and 2.8, respectively). In the present case-study, sleep onset latency and efficiency were altered on the night and in the week before injury occurrence. Individualized assessment of sleep during congested playing schedules may be useful to aid in preventing injury occurrence.


#4 A comparison of isomaltulose versus maltodextrin ingestion during soccer-specific exercise
Reference: Eur J Appl Physiol. 2017 Sep 19. doi: 10.1007/s00421-017-3719-5. [Epub ahead of print]
Authors: Stevenson EJ, Watson A, Theis S, Holz A, Harper LD, Russell M
Summary: The performance and physiological effects of isomaltulose and maltodextrin consumed intermittently during prolonged soccer-specific exercise were investigated. University soccer players (n = 22) performed 120 min of intermittent exercise while consuming 8% carbohydrate-electrolyte drinks (equivalent to ~ 20 g h-1) containing maltodextrin (Glycaemic Index: 90-100), isomaltulose (Glycaemic Index: 32) or a carbohydrate-energy-free placebo in a manner replicating the practices of soccer players (i.e., during warm-up and half-time). Physical (sprinting, jumping) and technical (shooting, dribbling) performance was assessed. Blood glucose and plasma insulin (both P < 0.001) concentrations varied by trial with isomaltulose maintaining > 13% higher blood glucose concentrations between 75 and 90 min versus maltodextrin (P < 0.05). A decline in glycaemia at 60 min in maltodextrin was attenuated with isomaltulose (-19 versus -4%; P = 0.015). Carbohydrates attenuated elevations in plasma epinephrine concentrations (P < 0.05), but isomaltulose proved most effective at 90 and 120 min. Carbohydrates did not attenuate IL-6 increases or reductions in physical or technical performances (all P > 0.05). Ratings of abdominal discomfort were influenced by trial (P < 0.05) with lower values for both carbohydrates compared to PLA from 60 min onwards. Although carbohydrates (~ 20 g h-1) did not attenuate performance reductions throughout prolonged soccer-specific exercise, isomaltulose maintained higher blood glucose at 75-90 min, lessened the magnitude of the exercise-induced rebound glycaemic response and attenuated epinephrine increases whilst maintaining similar abdominal discomfort values relative to maltodextrin. When limited opportunities exist to consume carbohydrates on competition-day, low-glycaemic isomaltulose may offer an alternative nutritional strategy for exercising soccer players.


#5 The Energy Cost of Running with the Ball in Soccer
Reference: Int J Sports Med. 2017 Sep 18. doi: 10.1055/s-0043-118340. [Epub ahead of print]
Authors: Piras A, Raffi M, Atmatzidis C, Merni F, Di Michele R
Summary: Running with the ball is a soccer-specific activity frequently used by players during match play and training drills. Nevertheless, the energy cost (EC) of on-grass running with the ball has not yet been determined. The purpose of this study was therefore to assess the EC of constant-speed running with the ball, and to compare it with the EC of normal running. Eight amateur soccer players performed two 6- min runs at 10 km/h on artificial turf, respectively with and without the ball. EC was measured with indirect calorimetry and, furthermore, estimated with a method based on players' accelerations measured with a GPS receiver. The EC measured with indirect calorimetry was higher in running with the ball (4.60±0.42 J/kg/m) than in normal running (4.19±0.33 J/kg/m), with a very likely moderate difference between conditions. Instead, a likely small difference was observed between conditions for EC estimated from GPS data (4.87±0.07 vs. 4.83±0.08 J/kg/m). This study sheds light on the energy expenditure of playing soccer, providing relevant data about the EC of a typical soccer-specific activity. These findings may be a reference for coaches to precisely determine the training load in drills with the ball, such as soccer-specific circuits or small-sided games.


#6 Practical nutritional recovery strategies for elite soccer players when limited time separates repeated matches
Reference: J Int Soc Sports Nutr. 2017 Sep 12;14:35. doi: 10.1186/s12970-017-0193-8. eCollection 2017.
Authors: Ranchordas MK, Dawson JT, Russell M
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5596842/pdf/12970_2017_Article_193.pdf
Summary: Specific guidelines that aim to facilitate the recovery of soccer players from the demands of training and a congested fixture schedule are lacking; especially in relation to evidence-based nutritional recommendations. The importance of repeated high level performance and injury avoidance while addressing the challenges of fixture scheduling, travel to away venues, and training commitments requires a strategic and practically feasible method of implementing specific nutritional strategies. Here we present evidence-based guidelines regarding nutritional recovery strategies within the context of soccer. An emphasis is placed on providing practically applicable guidelines for facilitation of recovery when multiple matches are played within a short period of time (i.e. 48 h). Following match-play, the restoration of liver and muscle glycogen stores (via consumption of ~1.2 g⋅kg-1⋅h-1 of carbohydrate) and augmentation of protein synthesis (via ~40 g of protein) should be prioritised in the first 20 min of recovery. Daily intakes of 6-10 g⋅kg-1 body mass of carbohydrate are recommended when limited time separates repeated matches while daily protein intakes of >1.5 g⋅kg-1 body mass should be targeted; possibly in the form of multiple smaller feedings (e.g., 6 × 20-40 g). At least 150% of the body mass lost during exercise should be consumed within 1 h and electrolytes added such that fluid losses are ameliorated. Strategic use of protein, leucine, creatine, polyphenols and omega-3 supplements could also offer practical means of enhancing post-match recovery.


#7 Risk factors for football injuries in young players aged 7 to 12 years
Reference: Scand J Med Sci Sports. 2017 Sep 18. doi: 10.1111/sms.12981. [Epub ahead of print]
Authors: Rossler R, Junge A, Chomiak J, Nemec K, Dvorak J, Lichtenstein E, Faude O
Summary: Football (soccer) is very popular amongst children. Little is known about risk factors for football injuries in children. The aim was to analyse potential injury risk factors in 7 to 12 year old players. We collected prospective data in Switzerland and the Czech Republic over two seasons. Coaches reported exposure of players (in hours), absence, and injury data via an internet-based registration system. We analysed time-to-injury data with extended Cox models accounting for correlations on team- and intra-person-level. We analysed injury risk in relation to age, sex, playing position, preferred foot, and regarding age-independent body height, body mass, and BMI. Further, we analysed injury risk in relation to playing surface. In total, 6,038 player seasons with 395,295 hours of football exposure were recorded and 417 injuries occurred. Injury risk increased by 46% (Hazard Ratio 1.46 [1.35; 1.58]; P<0.001) per year of life. Left-footed players had a higher injury risk (Hazard Ratio 1.53 [1.07; 2.19]; P=0.02) for training injuries compared to right-footed players. Injury risk was increased in age-adjusted taller players (higher percentile-rank). Higher match-training-ratios were associated with a lower risk of match injuries. Injury risk was increased on artificial turf (Rate Ratio 1.39 [1.12; 1.73]; P<0.001) and lower during indoor sessions (Rate Ratio 0.68 [0.52; 0.88]; P<0.001) compared to natural grass. Age is known as a risk factor in older players and was confirmed to be a risk factor in children's football. Playing surface and leg dominance have also been discussed previously as risk factors. Differences in injury risks in relation to sex should be investigated in the future.



American Football
#1 The Latarjet Procedure at the National Football League Scouting Combine: An Imaging and Performance Analysis
Reference: Orthop J Sports Med. 2017 Sep 1;5(9):2325967117726045. doi: 10.1177/2325967117726045. eCollection 2017 Sep.
Authors: LeBus GF, Chahla J, Sanchez G, Akamefula R, Moatshe G, Phocas A, Price MD, Whalen JM, LaPrade RF, Provencher MT
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5582664/pdf/10.1177_2325967117726045.pdf
Summary: The Latarjet procedure is commonly performed in the setting of glenoid bone loss for treatment of recurrent anterior shoulder instability; however, little is known regarding the outcomes of this procedure in elite American football players. The purpose was to (1) Determine the prevalence, clinical features, and imaging findings of elite college football athletes who present to the National Football League (NFL) Combine with a previous Latarjet procedure and (2) describe these athletes' performance in the NFL in terms of draft status and initial playing time. After review of all football players who participated in the NFL Combine from 2009 to 2016, any player with a previous Latarjet procedure was included in this study. Medical records, position on the field, and draft position were recorded for each player. In addition, imaging studies were reviewed to determine fixation type, hardware complications, and status of the bone block. For those players who were ultimately drafted, performance was assessed based on games played and started, total snaps, and percentage of eligible snaps in which the player participated during his rookie season. Overall, 13 of 2617 (<1%) players at the combine were identified with a previous Latarjet procedure. Radiographically, 8 of 13 (61%) showed 2-screw fixation, while 5 of 13 (39%) had 1 screw. Of the 13 players, 6 (46%) players demonstrated hardware complications. All players had evidence of degenerative changes on plain radiographs, with 10 (77%) graded as mild, 1 (8%) as moderate, and 2 (15%) as severe according to the Samilson Prieto classification. Six of the 13 (46%) players went undrafted, while the remaining 7 (54%) were drafted; however, no player participated in more than half of the plays for which he was eligible during his rookie season. Only a small percentage of players at the NFL Combine (<1%) had undergone a Latarjet procedure. High rates of postoperative complications and radiographically confirmed degenerative change were observed. Athletes who had undergone a Latarjet procedure demonstrated a variable amount of playing time, but none participated in more than half of their eligible plays during their rookie season.


#2 A Case Series of Pectoralis Major Injuries on One Collegiate Football Team
Reference: Curr Sports Med Rep. 2017 Sep/Oct;16(5):346-350. doi: 10.1249/JSR.0000000000000400.
Authors: Baker HP, Tjong VK, Varelas A, Wonais M, Terry MA.


#3 American football and other sports injuries may cause migraine/persistent pain decades later and can be treated successfully with electrical twitch-obtaining intramuscular stimulation (ETOIMS)
Reference: BMJ Innov. 2017 Apr;3(2):104-114. doi: 10.1136/bmjinnov-2016-000151. Epub 2017 Mar 24.
Authors: Chu J, McNally S, Bruyninckx F, Neuhauser D
Summary: Autonomous twitch elicitation at myofascial trigger points from spondylotic radiculopathies-induced denervation supersensitivity can provide favourable pain relief using electrical twitch-obtaining intramuscular stimulation (ETOIMS). The aim was to provide objective evidence that ETOIMS is safe and efficacious in migraine and persistent pain management due to decades-old injuries to head and spine from paediatric American football. An 83-year-old mildly hypertensive patient with 25-year history of refractory migraine and persistent pain self-selected to regularly receive fee-for-service ETOIMS 2/week over 20 months. He had 180 sessions of ETOIMS. Pain levels, blood pressure (BP) and heart rate/pulse were recorded before and immediately after each treatment alongside highest level of clinically elicitable twitch forces/session, session duration and intervals between treatments. Twitch force grades recorded were from 1 to 5, grade 5 twitch force being strongest. Initially, there was hypersensitivity to electrical stimulation with low stimulus parameters (500 µs pulse-width, 30 mA stimulus intensity, frequency 1.3 Hz). This resolved with gradual stimulus increments as tolerated during successive treatments. By treatment 27, autonomous twitches were noted. Spearman's correlation coefficients showed that pain levels are negatively related to twitch force, number of treatments, treatment session duration and directly related to BP and heart rate/pulse. Treatment numbers and session durations directly influence twitch force. At end of study, headaches and quality of life improved, hypertension resolved and antihypertensive medication had been discontinued. Using statistical process control methodology in an individual patient, we showed long-term safety and effectiveness of ETOIMS in simultaneous diagnosis, treatment, prognosis and prevention of migraine and persistent pain in real time obviating necessity for randomised controlled studies.


#4 Severe Exercise-Associated Hyponatremia in a Collegiate American Football Player
Reference: Curr Sports Med Rep. 2017 Sep/Oct;16(5):343-345. doi: 10.1249/JSR.0000000000000399.
Authors: Changstrom B, Brill J, Hecht S


#5 Mild Traumatic Brain Injury in a High School Football Player with Familial Hemiplegic Migraine: A Case Report
Reference: PM R. 2017 Sep 13. pii: S1934-1482(16)31114-5. doi: 10.1016/j.pmrj.2017.07.081. [Epub ahead of print]
Authors: Chand MR, Kanwar S, Peck E
Summary: Mild traumatic brain injury is a major concern in young athletes, with an estimated 1.6 to 3.8 million reported concussions in the US annually. Familial hemiplegic migraine is a rare autosomal-dominant condition characterized by sporadic episodes of transient unilateral motor weakness which may begin at any age. We present a case of a 17-year-old male with a history of familial hemiplegic migraine who suffered prolonged symptoms following a mild traumatic brain injury during sports participation.


#6 Erratum to: Editorial: Do Orthopaedic Surgeons Belong on the Sidelines at American Football Games?
Reference: Clin Orthop Relat Res. 2017 Sep 18. doi: 10.1007/s11999-017-5508-1. [Epub ahead of print]
Authors: Leopold SS, Dobbs MB, Gebhardt MC, Gioe TJ, Rimnac CM, Wongworawat MD
Summary: In the November Editorial, "Editorial: Do Orthopaedic Surgeons Belong on the Sidelines at American Football Games?" a statistic was attributed to a JAMA study (Ref. 10) that should have been attributed to an article from the New York Times (Ref. 16). The sentence in question should read: "We accept that critique, provided that the skeptics acknowledge that the best-case estimate in support of the safety of football would result in a CTE prevalence estimate of 9%, since only another 1200 ex-NFL players have died [16] since this research group [10] began studying football players' brains."


#7 Age of first exposure to American football and long-term neuropsychiatric and cognitive outcomes
Reference: Transl Psychiatry. 2017 Sep 19;7(9):e1236. doi: 10.1038/tp.2017.197.
Authors: Alosco ML, Kasimis AB, Stamm JM, Chua AS, Baugh CM, Daneshvar DH, Robbins CA, Mariani M, Hayden J, Conneely S, Au R, Torres A, McClean MD, McKee AC, Cantu RC, Mez J, Nowinski CJ, Martin BM, Chaisson CE, Tripodis Y, Stern RA
Download link: https://www.nature.com/tp/journal/v7/n9/pdf/tp2017197a.pdf
Summary: Previous research suggests that age of first exposure (AFE) to football before age 12 may have long-term clinical implications; however, this relationship has only been examined in small samples of former professional football players. We examined the association between AFE to football and behavior, mood and cognition in a large cohort of former amateur and professional football players. The sample included 214 former football players without other contact sport history. Participants completed the Brief Test of Adult Cognition by Telephone (BTACT), and self-reported measures of executive function and behavioral regulation (Behavior Rating Inventory of Executive Function-Adult Version Metacognition Index (MI), Behavioral Regulation Index (BRI)), depression (Center for Epidemiologic Studies Depression Scale (CES-D)) and apathy (Apathy Evaluation Scale (AES)). Outcomes were continuous and dichotomized as clinically impaired. AFE was dichotomized into <12 and ⩾12, and examined continuously. Multivariate mixed-effect regressions controlling for age, education and duration of play showed AFE to football before age 12 corresponded with >2 × increased odds for clinically impaired scores on all measures but BTACT: (odds ratio (OR), 95% confidence interval (CI): BRI, 2.16,1.19-3.91; MI, 2.10,1.17-3.76; CES-D, 3.08,1.65-5.76; AES, 2.39,1.32-4.32). Younger AFE predicted increased odds for clinical impairment on the AES (OR, 95% CI: 0.86, 0.76-0.97) and CES-D (OR, 95% CI: 0.85, 0.74-0.97). There was no interaction between AFE and highest level of play. Younger AFE to football, before age 12 in particular, was associated with increased odds for impairment in self-reported neuropsychiatric and executive function in 214 former American football players. Longitudinal studies will inform youth football policy and safety decisions.


#8 Cold-Water Immersion Cooling Rates in Football Linemen and Cross-Country Runners With Exercise-Induced Hyperthermia
Reference: J Athl Train. 2017 Sep 22. doi: 10.4085/1062-6050-52.7.08. [Epub ahead of print]
Authors: Godek SF, Morrison KE, Scullin G
Summary: Ideal and acceptable cooling rates in hyperthermic athletes have been established in average-sized participants. Football linemen (FBs) have a small body surface area (BSA) to mass ratio compared with smaller athletes, which hinders heat dissipation. The purpose was to determine cooling rates using cold-water immersion in hyperthermic FBs and cross-country runners (CCs). Nine FBs (age = 21.7 ± 1.7 years, height = 188.7 ± 4 cm, mass = 128.1 ± 18 kg, body fat = 28.9% ± 7.1%, lean body mass [LBM] = 86.9 ± 19 kg, BSA = 2.54 ± 0.13 m2, BSA/mass = 201 ± 21.3 cm2/kg, and BSA/LBM = 276.4 ± 19.7 cm2/kg) and 7 CCs (age = 20 ± 1.8 years, height = 176 ± 4.1 cm, mass = 68.7 ± 6.5 kg, body fat = 10.2% ± 1.6%, LBM = 61.7 ± 5.3 kg, BSA = 1.84 ± 0.1 m2, BSA/mass = 268.3 ± 11.7 cm2/kg, and BSA/LBM = 298.4 ± 11.7 cm2/kg). Participants ingested an intestinal sensor, exercised in a climatic chamber (39°C, 40% relative humidity) until either target core temperature (Tgi) was 39.5°C or volitional exhaustion was reached, and were immediately immersed in a 10°C circulated bath until Tgi declined to 37.5°C. A general linear model repeated-measures analysis of variance and independent t tests were calculated, with P < .05. Physical characteristics were different between groups. No differences existed in environmental measures or maximal Tgi (FBs = 39.12°C ± 0.39°C, CCs = 39.38°C ± 0.19°C; P = .12). Cooling times required to reach 37.5°C (FBs = 11.4 ± 4 minutes, CCs = 7.7 ± 0.06 minutes; P < .002) and therefore cooling rates (FBs = 0.156°C ± 0.06°C·min-1, CCs = .255°C ± 0.05°C·min-1; P < .002) were different. Strong correlations were found between cooling rate and body mass (r = -0.76, P < .001), total BSA (r = -0.74, P < .001), BSA/mass (r = 0.73, P < .001), LBM/mass (r = 0.72, P < .002), and LBM (r = -0.72, P < .002). Using cold-water immersion, the cooling rate in CCs (0.255°C·min-1) was greater than in FBs (0.156°C·min-1); however, both were considered ideal (≥0.155°C·min-1). Athletic trainers should realize that it likely takes considerably longer to cool large hyperthermic American-football players (>11 minutes) than smaller, leaner athletes (7.7 minutes). Cooling rates varied widely from 0.332°C·min-1 in a small runner to only 0.101°C·min-1 in a lineman, supporting the use of rectal temperature for monitoring during cooling.


#9 Head impact exposure measured in a single youth football team during practice drills
Reference: J Neurosurg Pediatr. 2017 Sep 12:1-9. doi: 10.3171/2017.5.PEDS16627. [Epub ahead of print]
Authors: Kelley ME, Kane JM, Espeland MA, Miller LE, Powers AK, Stitzel JD, Urban JE
Summary: This study evaluated the frequency, magnitude, and location of head impacts in practice drills within a youth football team to determine how head impact exposure varies among different types of drills. On-field head impact data were collected from athletes participating in a youth football team for a single season. Each athlete wore a helmet instrumented with a Head Impact Telemetry (HIT) System head acceleration measurement device during all preseason, regular season, and playoff practices. Video was recorded for all practices, and video analysis was performed to verify head impacts and assign each head impact to a specific drill. Eleven drills were identified: dummy/sled tackling, install, special teams, Oklahoma, one-on-one, open-field tackling, passing, position skill work, multiplayer tackle, scrimmage, and tackling drill stations. Generalized linear models were fitted to log-transformed data, and Wald tests were used to assess differences in head accelerations and impact rates. A total of 2125 impacts were measured during 30 contact practices in 9 athletes (mean age 11.1 ± 0.6 years, mean mass 44.9 ± 4.1 kg). Open-field tackling had the highest median and 95th percentile linear accelerations (24.7 g and 97.8 g, respectively) and resulted in significantly higher mean head accelerations than several other drills. The multiplayer tackle drill resulted in the highest head impact frequency, with an average of 0.59 impacts per minute per athlete, but the lowest 95th percentile linear accelerations of all drills. The front of the head was the most common impact location for all drills except dummy/sled tackling. Head impact exposure varies significantly in youth football practice drills, with several drills exposing athletes to high-magnitude and/or high-frequency head impacts. These data suggest that further study of practice drills is an important step in developing evidence-based recommendations for modifying or eliminating certain high-intensity drills to reduce head impact exposure and injury risk for all levels of play.

Wed

27

Sep

2017

Football is...(#16)

Straight-line sprinting might be rarely performed – however, the ones that are done might be important ones!

Wed

27

Sep

2017

Football is...(#15)

If you use SSG as a conditioning tool - Be aware of the goalkeeper!!!

Tue

26

Sep

2017

Latest research in football - week 37 - 2017

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 Strategies for injury prevention in Brazilian football: Perceptions of physiotherapists and practices of premier league teams
Reference: Phys Ther Sport. 2017 Jul 25;28:1-8. doi: 10.1016/j.ptsp.2017.07.004. [Epub ahead of print]
Authors: Meurer MC, Silva MF, Baroni BM
Summary: The purpose was to describe the physiotherapists perceptions and the current practices for injury prevention in elite football (soccer) clubs in Brazil. 16 of the 20 football clubs involved in the Brazilian premier league 2015 were involved in this study. Most physiotherapists (∼88%) were active in design, testing and application of prevention programs. Previous injury, muscle imbalance, fatigue, hydration, fitness, diet, sleep/rest and age were considered "very important" or "important" injury risk factors by all respondents. The methods most commonly used to detect athletes' injury risk were: monitoring of biochemical markers (100% of teams), isokinetic dynamometry (81%), questionnaires (75%), functional movement screen (56%), fleximetry (56%) and horizontal jump tests (50%). All clubs used strength training, functional training, core exercises and balance/proprioception exercises in their injury prevention program; and Nordic hamstring exercise and other eccentric exercises were used by 94% of clubs. "FIFA 11+" prevention program was adapted by 88% of clubs. Physiotherapists perceptions and current practices of injury prevention within Brazilian elite football clubs were similar to those employed in developed countries. There remains a gap between clinical practice and scientific evidence in high performance football.


#2 Prevention of Head and Brain Injuries in Football: Is there a Need to Ban Headings?
Reference: Sportverletz Sportschaden. 2017 Sep;31(3):143-153. doi: 10.1055/s-0043-113208. Epub 2017 Sep 4. [Article in German; Abstract available in German from the publisher]
Authors: Krutsch V, Krutsch W, Jansen P, Hoffmann H, Angele P, Lehmann J, Loose O, Gansslen A, Nerlich M, Weber J.
Summary: Football, the most popular sports worldwide, is associated with a high number of injuries. Head and brain injuries in football are less frequent, but may result in severe long-term damage. The mechanisms of these injuries in football are multifactorial, and the ball is rarely the main cause of a head injury. Short-term, medium-term and long-term consequences of headings in football are insufficiently examined, and there are hardly any case reports about severe episodes. Heading has been banned in US junior football since November 2015, which is understandable considering the higher risk for head injuries in popular American sports such as ice hockey or American football and people's fear associated with this risk. However, the decision to ban heading in football is not based on scientific results, and different experiences have been made in European football. Therefore, this decision should not simply be transferred to Europe. In fact, other injury prevention strategies for head injuries in junior football are necessary, such as the adaptation of ball sizes, which has already been implemented. It is not necessary to change match rules in the form of a general ban on heading in football. Further scientific studies are needed for standardisation in football worldwide.


#3 Does player unavailability affect football teams' match physical outputs? A two-season study of the UEFA champions league
Reference: J Sci Med Sport. 2017 Aug 24. pii: S1440-2440(17)30995-7. doi: 10.1016/j.jsams.2017.08.007. [Epub ahead of print]
Authors: Windt J, Ekstrand J, Khan KM, McCall A, Zumbo BD
Summary: Player unavailability negatively affects team performance in elite football. However, whether player unavailability and its concomitant performance decrement is mediated by any changes in teams' match physical outputs is unknown. We examined whether the number of players injured (i.e. unavailable for match selection) was associated with any changes in teams' physical outputs. Between-team variation was calculated by correlating average team availability with average physical outputs. Within-team variation was quantified using linear mixed modelling, using physical outputs - total distance, sprint count (efforts over 20km/h), and percent of distance covered at high speeds (>14km/h) - as outcome variables, and player unavailability as the independent variable of interest. To control for other factors that may influence match physical outputs, stage (group stage/knockout), venue (home/away), score differential, ball possession (%), team ranking (UEFA Club Coefficient), and average team age were all included as covariates. Teams' average player unavailability was positively associated with the average number of sprints they performed in matches across two seasons. Multilevel models similarly demonstrated that having 4 unavailable players was associated with 20.8 more sprints during matches in 2015/2016, and with an estimated 0.60-0.77% increase in the proportion of total distance run above 14km/h in both seasons. Player unavailability had a possibly positive and likely positive association with total match distances in the two respective seasons. Having more players injured and unavailable for match selection was associated with an increase in teams' match physical outputs.


#4 Hypernetworks Reveal Compound Variables That Capture Cooperative and Competitive Interactions in a Soccer Match
Reference: Front Psychol. 2017 Aug 28;8:1379. doi: 10.3389/fpsyg.2017.01379. eCollection 2017.
Authors: Ramos J, Lopes RJ, Marques P, Araujo D
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5581353/pdf/fpsyg-08-01379.pdf
Summary: The combination of sports sciences theorization and social networks analysis (SNA) has offered useful new insights for addressing team behavior. However, SNA typically represents the dynamics of team behavior during a match in dyadic interactions and in a single cumulative snapshot. This study aims to overcome these limitations by using hypernetworks to describe illustrative cases of team behavior dynamics at various other levels of analyses. Hypernetworks simultaneously access cooperative and competitive interactions between teammates and opponents across space and time during a match. Moreover, hypernetworks are not limited to dyadic relations, which are typically represented by edges in other types of networks. In a hypernetwork, n-ary relations (with n > 2) and their properties are represented with hyperedges connecting more than two players simultaneously (the so-called simplex-plural, simplices). Simplices can capture the interactions of sets of players that may include an arbitrary number of teammates and opponents. In this qualitative study, we first used the mathematical formalisms of hypernetworks to represent a multilevel team behavior dynamics, including micro (interactions between players), meso (dynamics of a given critical event, e.g., an attack interaction), and macro (interactions between sets of players) levels. Second, we investigated different features that could potentially explain the occurrence of critical events, such as, aggregation or disaggregation of simplices relative to goal proximity. Finally, we applied hypernetworks analysis to soccer games from the English premier league (season 2010-2011) by using two-dimensional player displacement coordinates obtained with a multiple-camera match analysis system provided by STATS (formerly Prozone). Our results show that (i) at micro level the most frequently occurring simplices configuration is 1vs.1 (one attacker vs. one defender); (ii) at meso level, the dynamics of simplices transformations near the goal depends on significant changes in the players' speed and direction; (iii) at macro level, simplices are connected to one another, forming "simplices of simplices" including the goalkeeper and the goal. These results validate qualitatively that hypernetworks and related compound variables can capture and be used in the analysis of the cooperative and competitive interactions between players and sets of players in soccer matches.


#5 Monitoring training load and fatigue in soccer players with physiological markers
Reference: Physiol Behav. 2017 Sep 5. pii: S0031-9384(17)30278-0. doi: 10.1016/j.physbeh.2017.09.004. [Epub ahead of print]
Authors: Djaoui L, Haddad M, Chamari K, Dellal A
Summary: The quantification and monitoring of training load (TL) has been the topic of many scientific works in the last fifteen years. TL monitoring helps coaches to individually prescribe, follow-up, analyse, adjust and programme training sessions. In particular, the aim of the present review was to provide a critical literature report regarding different physiological markers of TL monitoring, particularly in soccer, as the load is specific to individual sports. Therefore, the interests and limitations of heart rate (HR), HR variability (HRV) and biochemical variables (blood, urinary and hormonal variations) were analysed, with a special focus on daily measures (before, during and after training) and monitoring throughout a whole season. It appears that the most relevant markers were the resting HR before training, HR reserve during training, HRV during rest days, blood lactate, and blood and salivary immunological status in follow-ups throughout the season. Urinary markers indicative of the players' hydration status also deserve attention. However, these objective markers should be considered with a subjective marker of TL such as the rating of perceived exertion to give a more precise quantification of TL and its perception. Future research could be directed towards urinary marker analysis and the analysis of specific markers of TL, which could be related to injury occurrence and to performance during competition.


#6 Perception, Action, and Cognition of Football Referees in Extreme Temperatures: Impact on Decision Performance
Reference: Front Psychol. 2017 Aug 29;8:1479. doi: 10.3389/fpsyg.2017.01479. eCollection 2017.
Authors: Gaoua N, de Oliveira RF, Hunter S
Summary: Different professional domains require high levels of physical performance alongside fast and accurate decision-making. Construction workers, police officers, firefighters, elite sports men and women, the military and emergency medical professionals are often exposed to hostile environments with limited options for behavioral coping strategies. In this (mini) review we use football refereeing as an example to discuss the combined effect of intense physical activity and extreme temperatures on decision-making and suggest an explicative model. In professional football competitions can be played in temperatures ranging from -5°C in Norway to 30°C in Spain for example. Despite these conditions, the referee's responsibility is to consistently apply the laws fairly and uniformly, and to ensure the rules are followed without waning or adversely influencing the competitiveness of the play. However, strenuous exercise in extreme environments imposes increased physiological and psychological stress that can affect decision-making. Therefore, the physical exertion required to follow the game and the thermal strain from the extreme temperatures may hinder the ability of referees to make fast and accurate decisions. Here, we review literature on the physical and cognitive requirements of football refereeing and how extreme temperatures may affect referees' decisions. Research suggests that both hot and cold environments have a negative impact on decision-making but data specific to decision-making is still lacking. A theoretical model of decision-making under the constraint of intense physical activity and thermal stress is suggested. Future naturalistic studies are needed to validate this model and provide clear recommendations for mitigating strategies.


#7 Trends in aggressive play and refereeing among the top five European soccer leagues
Reference: J Sports Sci. 2017 Sep 12:1-9. doi: 10.1080/02640414.2017.1377911. [Epub ahead of print]
Authors: Sapp RM, Spangenburg EE, Hagberg JM
Summary: Current trends suggest professional soccer is becoming less aggressive, with England often argued to have the most aggressive of the top European leagues. The purpose of this study was to investigate differences in fouls and cards as indicators of aggressive play in the first divisions of England, France, Germany, Italy, and Spain over the past decade. Number of fouls per match and per yellow card has decreased in all leagues since 2007/08, though attempted tackles per foul has not changed or has increased. A lack of substantial rule changes suggests players have become less aggressive in tackling as opposed to referees becoming more lenient. Total number of fouls and cards per match were consistently lower in the English Premier League, however attempted tackles per foul was higher. The data also demonstrate the notions of home advantage and potentially referee bias, since referees tended to call more fouls and award more cards to away teams. Lastly, number of attempted tackles per foul and yellow cards received exhibited the strongest correlations with final league position across the leagues. In conclusion, our data support that elite European soccer has become less aggressive and the English Premier League is the most aggressive league.


#8 Effects of repeated-sprints with changes of direction on youth soccer player's performance: Impact of initial fitness level
Reference: J Strength Cond Res. 2017 Sep 6. doi: 10.1519/JSC.0000000000002232. [Epub ahead of print]
Authors: Nakamura FY, Sanchez-Sanchez J, Ramirez-Campillo R, Petisco C, Gonzalo-Skok O, Rodriguez-Fernandez A, Minano J
Summary: The aim of this study was to assess the effect of an 8-week repeated sprint with change of direction training program on repeated sprint, intermittent endurance and change of direction performance in youth soccer players with different aerobic fitness levels. Athletes were randomly assigned into a soccer-only (n=9; age, 14.9±0.4 yr) and soccer plus repeated sprint with change of direction (RS-COD) training programs for players with high (n=10; age, 14.4±0.5 yr) and low (n=10; age, 14.4±0.5 yr) aerobic fitness. RS-COD was completed two days per week, involving three sets of ten 18-m sprints with two changes of direction of 90°. The soccer-only group achieved greater improvements in intermittent endurance (ES = 0.61) and sprint decrement during RS ability test (ES = 0.77) compared to the RS-COD groups (ES = 0.19 to 0.24; ES = -0.27 to 0.02; respectively). RS-COD training improved repeated sprint (ES = 0.16 to 0.38) and change of direction (ES = 0.48) performance in high, but not in low fitness players (ES = 0.03 to 0.13; ES = 0.16; respectively). Moreover, improvements in repeated sprint and change of direction were (possibly) greater in high compared to low fitness and soccer-only trained players (possibly to very likely). In conclusion, although RS-COD training may positively affect repeated sprint and change of direction performance, its effects may vary according to the initial aerobic fitness of youth soccer players, with trivial effect on intermittent endurance in high-aerobic fitness players and possible beneficial effect on low-aerobic fitness players.


#9 A Cross-Continental Study on Children's Drawings of Football Players: Implications for Understanding Key Issues and Controversies in Human Figure Drawings
Reference: Eur J Psychol. 2017 Aug 31;13(3):455-471. doi: 10.5964/ejop.v13i3.1237. eCollection 2017 Aug.
Authors: Baluch B, Duffy LJ, Badami R, Pereira ECA
Summary: Professionals examine various aspects of girls' and boys' drawings as a way of understanding their intelligence, personality and emotional state. However, the extent to which such measures could be universally generalised or attributed to a specific cultural norm is still a debatable issue. In the present study five key features of children's drawings namely: the size (height) of the drawings, profile or full face, figure in action or static, shaded or non-shaded and the nature of additional details were examined from a cross-cultural perspective, and by providing a topic (football) for which children's drawing of a human figure could provide opportunities for the latter indices to manifest and flourish. Children from three countries; England, Iran and Brazil, representing three continents took part in this study. The participants were asked to draw a football player from their own country and from the other participating countries. The results showed that Brazilian children differ from Iranian and English children by drawing significantly smaller figures and putting more football action in the drawings. Shading of the figure drawn was more prevalent amongst English children. Such findings have implications for the interpretation of key aspects of children's drawings in educational, clinical and therapeutic settings and from a universal vs. culturally-specific viewpoint.


American Football
#1 What is the Value of a National Football League Draft Pick? An Analysis Based on Changes Made in the Collective Bargaining Agreement
Reference:  J Strength Cond Res. 2017 Jun 2. doi: 10.1519/JSC.0000000000002045. [Epub ahead of print]
Authors: Kraeutler MJ, Carver TJ, Belk JW, McCarty EC
Summary: The purpose of this study was to analyze and compare the value of players drafted in early rounds of the NFL Draft since the new collective bargaining agreement (CBA) began in 2011. The NFL's player statistics database and database of player contract details were searched for players drafted in the first three rounds of the 2011 to 2013 NFL Drafts. Performance outcomes specific to each position were divided by each player's salary to calculate a value statistic. Various demographics, NFL Combine results, and total number of games missed due to injury were also recorded for each player. These statistics were compared within each position between players selected in the 1st round of the NFL Draft (Group A) versus those drafted in the 2nd or 3rd round (Group B). A total of 147 players were included (Group A 35, Group B 112). Overall, players in Group A were significantly taller (p < 0.01) and heavier (p = 0.037) than players in Group B. Group B demonstrated significantly greater value statistics than Group A for quarterbacks (p = 0.028), wide receivers (p < 0.001), defensive tackles (p = 0.019), and cornerbacks (p < 0.001). No significant differences were found between groups with regard to number of games missed due to injury. Players drafted in the 2nd or 3rd rounds of the NFL Draft often carry more value than those drafted in the 1st round. NFL teams may wish to more frequently trade down in the Draft rather than trading up.


#2 Nano-Composite Foam Sensor System in Football Helmets
Reference: Ann Biomed Eng. 2017 Sep 7. doi: 10.1007/s10439-017-1910-9. [Epub ahead of print]
Authors: Merrell AJ, Christensen WF, Seeley MK, Bowden AE, Fullwood DT
Summary: American football has both the highest rate of concussion incidences as well as the highest number of concussions of all contact sports due to both the number of athletes and nature of the sport. Recent research has linked concussions with long term health complications such as chronic traumatic encephalopathy and early onset Alzheimer's. Understanding the mechanical characteristics of concussive impacts is critical to help protect athletes from these debilitating diseases and is now possible using helmet-based sensor systems. To date, real time on-field measurement of head impacts has been almost exclusively measured by devices that rely on accelerometers or gyroscopes attached to the player's helmet, or embedded in a mouth guard. These systems monitor motion of the head or helmet, but do not directly measure impact energy. This paper evaluates the accuracy of a novel, multifunctional foam-based sensor that replaces a portion of the helmet foam to measure impact. All modified helmets were tested using a National Operating Committee Standards for Athletic Equipment-style drop tower with a total of 24 drop tests (4 locations with 6 impact energies). The impacts were evaluated using a headform, instrumented with a tri-axial accelerometer, mounted to a Hybrid III neck assembly. The resultant accelerations were evaluated for both the peak acceleration and the severity indices. These data were then compared to the voltage response from multiple Nano Composite Foam sensors located throughout the helmet. The foam sensor system proved to be accurate in measuring both the HIC and Gadd severity index, as well as peak acceleration while also providing additional details that were previously difficult to obtain, such as impact energy.


#3 Examining Play Counts and Measurements of Injury Incidence in Youth Football
Reference: J Athl Train. 2017 Sep 7. doi: 10.4085/1062-6050-52.7.06. [Epub ahead of print]
Authors: Kerr ZY, Yeargin SW, Djoko A, Dalton SL, Niceley MM, Dompier TP
Summary: Whereas researchers have provided estimates for the number of head impacts sustained within a youth football season, less is known about the number of plays across which such impact exposure occurs.  The objective was to estimate the number of plays in which youth football players participated during the 2013 season and to estimate injury incidence through play-based injury rates. Youth football players (N = 2098; age range, 5-15 years) from 105 teams in 12 recreational leagues across 6 states participated in this study.  We calculated the average number of athlete-plays per season and per game using independent-samples t tests to compare age groups (5-10 years old versus 11-15 years old) and squad sizes (<20 versus ≥20 players); game injury rates per 1000 AE and per 10 000 athlete-plays; and injury rate ratios (IRRs) with 95% confidence intervals (CIs) to compare age groups. On average, youth football players played 333.9 ± 178.5 plays per season and 43.9 ± 24.0 plays per game. Age groups (5- to 10-year-olds versus 11- to 15-year-olds) did not differ in the average number of plays per season (335.8 versus 332.3, respectively; t2086.4 = 0.45, P = .65) and per game (44.1 versus 43.7, respectively; t2092.3 = 0.38, P = .71). However, players from smaller teams participated in more plays per season (373.7 versus 308.0; t1611.4 = 8.15, P < .001) and per game (47.7 versus 41.4; t1523.5 = 5.67, P < .001). Older players had a greater game injury rate than younger players when injury rates were calculated per 1000 AEs (23.03 versus 17.86/1000 AEs; IRR = 1.29; 95% CI = 1.04, 1.60) or per 10 000 athlete- plays (5.30 versus 4.18/10 000 athlete-plays; IRR = 1.27; 95% CI = 1.02, 1.57). A larger squad size was associated with a lower average number of plays per season and per game. Increasing youth football squad sizes may help reduce head-impact exposure for individual players. The AE-based injury rates yielded effect estimates similar to those of play-based injury rates.


#4 Editorial: Do Orthopaedic Surgeons Belong on the Sidelines at American Football Games?
Reference: Clin Orthop Relat Res. 2017 Sep 5. doi: 10.1007/s11999-017-5483-6. [Epub ahead of print]
Authors: Leopold SS, Dobbs MB, Gebhardt MC, Gioe TJ, Rimnac CM, Wongworawat MD
Download link: https://link.springer.com/content/pdf/10.1007%2Fs11999-017-5483-6.pdf



Australian Football
#1 Australian Football League concussion guidelines: what do community players think?
Reference: BMJ Open Sport Exerc Med. 2016 Nov 28;2(1):e000169. doi: 10.1136/bmjsem-2016-000169. eCollection 2016.
Authors: White PE, Donaldson A, Sullivan SJ, Newton J, Finch CF
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5566260/pdf/bmjsem-2016-000169.pdf
Summary: Preventing concussion in sport is a global challenge. To assess community-level adult male Australian Football players' views on following the Australian Football League's (AFL) concussion guidelines. 3 focus groups, each comprising 6 players from 1 regional league, were conducted until saturation of issues raised. Discussions followed a semistructured script and were audio-recorded and transcribed verbatim. Thematic analysis was conducted by 2 coders independently. Identified advantages of the guidelines included highlighting the seriousness of concussion; changing the culture around playing with concussion and shifting return-to-play decision responsibility from players to others. Disadvantages included players being removed from play unnecessarily; removal of players' rights to decide if they are fit to play and players changing their behaviours to avoid being removed from play. Identified facilitators to guideline use included local league enforcement; broad information dissemination and impartial medically trained staff to assess concussion. Identified barriers to guideline use included players' desire to play at all costs; external pressure that encouraged players to return to play prematurely; and inconvenience and cost. Players generally understand that the AFL concussion guidelines protect their long-term welfare. However, their desire to play at all costs and help their team win is a common barrier to reporting concussion and adhering to guidelines. Leagues should take a lead role by mandating and enforcing the use of the guidelines and educating coaches, game day medical providers and players. The return-to-play component of the guidelines is complex and needs further consideration in the context of community sport.


#2 Effect of Prior Injury on Changes to Biceps Femoris Architecture across an Australian Football League Season
Reference: Med Sci Sports Exerc. 2017 Oct;49(10):2102-2109. doi: 10.1249/MSS.0000000000001333.
Authors: Timmins RG, Bourne MN, Hickey JT, Maniar N, Tofari PJ, Williams MD, Opar DA
Summary: The purpose was to assess in-season alterations of biceps femoris long head (BFlh) fascicle length in elite Australian footballers with and without a history of unilateral hamstring strain injury (HSI) in the past 12 months. Thirty elite Australian football players were recruited. Twelve had a history of unilateral HSI. Eighteen had no HSI history. All had their BFlh architecture assessed at approximately monthly intervals, six times across a competitive season. The previously injured limb's BFlh fascicles increased from the start of the season and peaked at week 5. Fascicle length gradually decreased until the end of the season, where they were shortest. The contralateral uninjured limb's fascicles were the longest when assessed at week 5 and showed a reduction in-season where weeks 17 and 23 were shorter than week 1. Control group fascicles were longest at week 5 and reduced in-season. The previously injured limb's BFlh fascicles were shorter than the control group at all weeks and the contralateral uninjured limb at week 5. Compared with the control group, the contralateral uninjured limb had shorter fascicles from weeks 9 to 23. Athletes with a history of HSI end the season with shorter fascicles than they start. Limbs without a history of HSI display similar BFlh fascicle lengths at the end of the season as they begin with. All athletes increase fascicle length at the beginning of the season; however, the extent of the increase differed based on history of HSI. These findings show that a HSI history may influence structural adaptation of the BFlh in-season.


#3 The validity and reliability of the sphygmomanometer for hip strength assessment in Australian football players
Reference: Physiother Theory Pract. 2017 Sep 11:1-6. doi: 10.1080/09593985.2017.1374492. [Epub ahead of print]
Authors: Toohey LA, de Noronha M, Taylor C, Thomas J
Summary: The purpose was to investigate the intra-rater and inter-rater reliability of the sphygmomanometer for the assessment of the adductor squeeze test and isometric hip abduction strength and to investigate the concurrent validity of the sphygmomanometer for the assessment of hip muscular strength. Thirty-two healthy adult male community Australian football players (age 23.9 ± 4.5 years) were assessed by two blinded raters that measured the strength of the adductor squeeze test and isometric hip abduction, using a commercially available sphygmomanometer. Concurrent validity was calculated using handheld dynamometry as the reference standard. Moderate to high intra-rater reliability (ICC = 0.61 to 0.92) and high inter-rater reliability (ICC = 0.77 to 0.91) were found. High concurrent validity (Pearson's r = 0.77 to 0.91) was established. Sixteen of the participants reached the maximal reading of the sphygmomanometer, demonstrating a ceiling effect. A sphygmomanometer is a cost-efficient device that appears to be both reliable and valid for the assessment of hip strength, offering clinicians an alternate and easily accessible option to obtain objective strength data. A ceiling effect may limit the application of the sphygmomanometer as a strength measurement device in stronger individuals.

Tue

26

Sep

2017

Football is...(#14)

There are various high-speed variations that a footballer needs to perform during the game.

Fri

22

Sep

2017

Football is...(#13)

Control the ball - control the game

Thu

21

Sep

2017

Football is...(#12)

Running laps is good for footballers…unless you know SSG?

Thu

21

Sep

2017

Latest research in football - week 36 - 2017

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 Bone Turnover Markers and Lean Mass in Pubescent Boys: Comparison Between Elite Soccer Players and Controls
Reference: Pediatr Exerc Sci. 2017 Sep 5:1-20. doi: 10.1123/pes.2017-0090. [Epub ahead of print]
Authors: Nebigh A, Abed ME, Borji R, Sahli S, Sellami S, Tabka Z, Rebai H
Summary: The aim of this study was to examine the relationship between bone mass and bone turnover markers with lean mass in pubescent soccer players. Two groups participated in this study 65 elite young soccer players that trained from 6 to 8 hours per week and 60 controls. Bone mineral density (BMD), bone mineral content (BMC) in the whole body, lower limbs, lumbar spine, and femoral neck, biochemical markers of osteocalcin (OC), bone-specific alkaline phosphatase (BAP), C-telopeptide type I collagen (CTX) and total lean mass were assessed. Young soccer players showed higher BMD and BMC in the whole body and weight-bearing sites (p<0.001). Indeed, total lean mass correlated with whole body BMD and BMC (p<0.001). There were significant differences within the bone formation markers and OC (formation) / CTX (resorption) ratio between young soccer players compared to the control group; but no significant difference in (CTX) between the two groups was observed. The study showed a significant positive correlation between (BAP), (OC) and total lean mass (r = 0.29; r = 0.31; p<0.05, respectively) only for the young soccer players. Findings of this study highlight the importance of soccer practice for bone mineral parameters and bone turnover markers during the puberty stage.


#2 Neuromuscular Responses to Conditioned Soccer Sessions Assessed Via GPS-Embedded Accelerometers: Insights Into Tactical Periodization
Reference: Int J Sports Physiol Perform. 2017 Sep 5:1-21. doi: 10.1123/ijspp.2017-0045. [Epub ahead of print]
Authors: Buchheit M, Lacome M, Cholley Y, Simpson BM
Summary: The purpose was to 1) examine the reliability of field-based running-specific measures of neuromuscular function assessed via GPS-embedded accelerometers and 2) examine their responses to three typical conditioned sessions (i.e., Strength, Endurance and Speed) in elite soccer players. Before and immediately after each session, vertical jump (CMJ) and adductors squeeze strength (Groin) performances were recorded. Players also performed a 4-min run at 12 km/h followed by 4 ~60-m runs (run =12 s, r =33 s). GPS (15-Hz) and accelerometer (100 Hz) data collected during the four runs + the recovery periods excluding the last recovery period were used to derive vertical stiffness (K), peak loading force (peak force over all the foot-strikes, Fpeak) and propulsion efficiency (i.e., ratio between velocity and force loads, Vl/Fl). Typical errors were small (CMJ, Groin, K and Vl/Fl) and moderate (Fpeak), with moderate (Fpeak), high (K and Vl/Fl) and very high ICC (CMJ and Groin). After all sessions, there were small decreases in Groin and increases in K, while changes in F were all unclear. In contrast, the CMJ and Vl/Fl ratio responses were session-dependent: small increase in CMJ after Speed and Endurance, but unclear changes after Strength; the Vl/Fl ratio increased largely after Strength, while there was a small and a moderate decrease after the Endurance and Speed, respectively. Running-specific measures of neuromuscular function assessed in the field via GPS-embedded accelerometers show acceptable levels of reliability. While the three sessions examined may be associated with limited neuromuscular fatigue, changes in neuromuscular performance and propulsion-efficiency are likely session objective-dependent.


#3 How Game Location Affects Soccer Performance: T-Pattern Analysis of Attack Actions in Home and Away Matches
Reference: Front Psychol. 2017 Aug 21;8:1415. doi: 10.3389/fpsyg.2017.01415. eCollection 2017.
Authors: Diana B, Zurloni V, Elia M, Cavalera CM, Jonsson GK, Anguera MT
Download link: http://journal.frontiersin.org/article/10.3389/fpsyg.2017.01415/full
Summary: The influence of game location on performance has been widely examined in sport contexts. Concerning soccer, game-location affects positively the secondary and tertiary level of performance; however, there are fewer evidences about its effect on game structure (primary level of performance). This study aimed to detect the effect of game location on a primary level of performance in soccer. In particular, the objective was to reveal the hidden structures underlying the attack actions, in both home and away matches played by a top club (Serie A 2012/2013-First Leg). The methodological approach was based on systematic observation, supported by digital recordings and T-pattern analysis. Data were analyzed with THEME 6.0 software. A quantitative analysis, with nonparametric Mann-Whitney test and descriptive statistics, was carried out to test the hypotheses. A qualitative analysis on complex patterns was performed to get in-depth information on the game structure. This study showed that game tactics were significantly different, with home matches characterized by a more structured and varied game than away matches. In particular, a higher number of different patterns, with a higher level of complexity and including more unique behaviors was detected in home matches than in the away ones. No significant differences were found in the number of events coded per game between the two conditions. THEME software, and the corresponding T-pattern detection algorithm, enhance research opportunities by going further than frequency-based analyses, making this method an effective tool in supporting sport performance analysis and training.


#4 Prevalence of FAI radiographic hip abnormalities in elite soccer players: are there differences related to skeletal maturity?
Reference: BMJ Open Sport Exerc Med. 2017 Feb 21;2(1):e000162. doi: 10.1136/bmjsem-2016-000162. eCollection 2016.
Authors: Monckeberg J, Amenabar T, Rafols C, Garcia N, Yañez R
Download link: http://bmjopensem.bmj.com/content/bmjosem/2/1/e000162.full.pdf
Summary: Femoroacetabular impingement (FAI) can be a source of hip pain in young adults. Some reports have revealed that participation in high-impact sports may play a role in the development of cam deformity, and there is a higher prevalence of signs of cam impingement in asymptomatic adolescents who participate in soccer and basketball than in non-athlete controls; however, current evidence is scarce regarding the initiation and development of deformities. The aim of this study was to evaluate the prevalence of radiographic hip abnormalities related to FAI in young elite soccer players and compare this with findings in a group of adult elite soccer players. Anteroposterior pelvic and cross-table hip radiographs were obtained for 75 young elite soccer players with skeletal immaturity (group 1) and for 75 adult elite soccer players (group 2), all of whom were previously asymptomatic and had no history of hip disease. After exclusion, group 1 included 72 patients, and group 2 included 70 patients. Radiological signs of FAI were evaluated. 34 subjects in groups 1 and 2 demonstrated cam morphology. The prevalence of pincer morphology was 30 in group 1 and 36 in group 2. However, these differences were not statistically significant. We found no differences in the prevalence of FAI radiological signs between soccer players in their late adolescence and adult soccer players.


#5 Comparison of physical activities of female football players in junior high school and high school
Reference: J Phys Ther Sci. 2017 Aug;29(8):1352-1356. doi: 10.1589/jpts.29.1352. Epub 2017 Aug 10.
Authors: Inoue Y, Otani Y, Takemasa S
Summary: This study aimed to compare physical activities between junior high school and high school female football players in order to explain the factors that predispose to a higher incidence of sports injuries in high school female football players. Twenty-nine female football players participated. Finger floor distance, the center of pressure during single limb stance with eyes open and closed, the 40-m linear sprint time, hip abduction and extension muscle strength and isokinetic knee flexion and extension peak torque were measured. The modified Star Excursion Balance Test, the three-steps bounding test and three-steps hopping tests, agility test 1 (Step 50), agility test 2 (Forward run), curl-up test for 30 seconds and the Yo-Yo intermittent recovery test were performed. The high school group was only significantly faster than the junior high school group in the 40-m linear sprint time and in the agility tests. The distance of the bounding test in the high school group was longer than that in the junior high school group. Agility and speed increase with growth; however, muscle strength and balance do not develop alongside. This unbalanced development may cause a higher incidence of sports injuries in high school football players.


#6 Descriptive analysis of objectively assessed physical activity among talented soccer players: a study of three Norwegian professional football clubs
Reference: BMJ Open Sport Exerc Med. 2017 Feb 21;2(1):e000178. doi: 10.1136/bmjsem-2016-000178. eCollection 2016.
Authors: Saether SA, Aspvik NP
Download link: http://bmjopensem.bmj.com/content/bmjosem/2/1/e000178.full.pdf
Summary: Talented football players are expected to overcome large training and match loads, indicating a high weekly level of physical activity (PA). With the use of accelerometers, the aim of this study was to objectively describe the players' total time spent in moderate-to-vigorous PA (MVPA), vigorous PA (VPA) and very vigorous PA (VVPA) per day in 1 week. Since high-intensity PA has been highlighted as important in terms of overall PA load, we also included 2 and 4 min bouts of VPA. Data were collected in three junior teams in professional football clubs in March (club 1: 2014, club 2: 2012 and club 3: 2011). A one-way analysis of variance was applied to analyse differences between the three respective clubs. The players averaged 77.2-86.2 min in MVPA, 14.9-18.5 min in VPA and 1.0-3.1 in VVPA per day. While there were no differences in total time spent in MVPA and VPA per day, VVPA was significantly higher in club 1 (p<0.01) compared with clubs 2 and 3. Moreover, when using the VPA bouts, club 3 (p<0.01) achieved significantly more time in this intensity compared with clubs 1 and 2. This study acknowledges the importance of including both club-related and non-club-related PA when analysing talented football players' PA level. We suggest that future studies examining players' PA with accelerometers should emphasise time spent in high-intensity PA and how this is associated with physical overload, psychological burnout and risk of injury.


#7 Cryotherapy Re-Invented: Application of Phase Change Material for Recovery in Elite Soccer
Reference: Int J Sports Physiol Perform. 2017 Sep 5:1-21. doi: 10.1123/ijspp.2017-0334. [Epub ahead of print]
Authors: Clifford T, Abbott W, Kwiecien SY, Howatson G, McHugh MP
Summary: This study examined whether donning lower body garments fitted with cooled phase change material (PCM) would enhance recovery after a soccer match. In a randomized, crossover design, eleven elite-soccer players from the reserve squad of a team in the 2nd highest league in England wore PCM cooled to 15°C (PCMcold) or left at ambient temperature (PCMamb; sham control) for 3 h after a soccer match. To assess recovery, countermovement jump (CMJ) height, maximal isometric voluntary contraction (MIVC), muscle soreness (MS), and the adapted Brief Assessment of Mood Questionnaire (BAM+) were measured before, 12, 36 and 60 h after each match. Pre and post intervention, a belief questionnaire (BFQ) was completed to determine perceived effectiveness of each garment. Results are comparisons between the two conditions at each time point post-match. MIVC at 36 h post was greater with PCMcold vs. PCMwarm (P =0.005; ES=1.59; 95% CI=3.9 to 17.1%). MIVC also tended to be higher at 60 h post (P =0.051; ES=0.85; 95% CI= -0.4 to 11.1%). MS was 26.5% lower in PCMcold vs. PCMwarm at 36 h (P =0.02; ES=1.7; 95% CI= -50.4 mm to -16.1 mm) and 24.3% lower at 60 h (P =0.039; ES=1.1; 95% CI= -26.9 mm to -0.874 mm). There were no between condition differences in post-match CMJ height or BAM+ (P >0.05). The BFQ revealed that players felt the PCMcold was more effective than the PCMamb after the intervention (P =0.004). PCM cooling garments provide a practical means of delivering prolonged post-exercise cooling and thereby accelerating recovery in elite soccer players.


#8 Adding Fish Oil to Whey Protein, Leucine and Carbohydrate Over a 6 Week Supplementation Period Attenuates Muscle Soreness Following Eccentric Exercise in Competitive Soccer Players
Reference: Int J Sport Nutr Exerc Metab. 2017 Sep 5:1-28. doi: 10.1123/ijsnem.2017-0161. [Epub ahead of print]
Authors: Philpott JD, Donnelly C, Walshe IH, Dick J, Galloway SDR, Tipton KD, Witard OC
Summary: Soccer players often experience eccentric exercise-induced muscle damage given the physical demands of soccer match-play. Since long chain n-3 polyunsaturated fatty acids (n-3PUFA) enhance muscle sensitivity to protein supplementation, dietary supplementation with a combination of fish oil-derived n-3PUFA, protein and carbohydrate may promote exercise recovery. This study examined the influence of adding n-3PUFA to a whey protein, leucine and carbohydrate containing beverage over a 6 week supplementation period on physiological markers of recovery measured over 3 days following eccentric exercise. Competitive soccer players were assigned to one of three conditions (2 × 200mL): FO (n=10) contained n-3PUFA (1100mg DHA/EPA - approx. 550mg DHA, 550mg EPA), whey protein (15g), leucine (1.8g) and carbohydrate (20g); PRO (n=10) contained whey protein (15g), leucine (1.8g) and carbohydrate (20g) and CHO (n=10) contained carbohydrate (24g). Eccentric exercise consisted of unilateral knee extension/flexion contractions on both legs separately. Maximal force production was impaired by 22% during the 72 hour recovery period following eccentric exercise (p<0.05). Muscle soreness, expressed as AUC during 72 hour recovery, was less in FO (1948±1091 mm×72 h) than PRO (4640±2654 mm×72h, p<0.05) and CHO (4495±1853 mm×72h p=0.10). Blood concentrations of creatine kinase, expressed as AUC, were ~60% lower in FO compared to CHO (p<0.05) and tended to be lower (~39%, p = 0.07) than PRO. No differences in muscle function, soccer performance or blood c-reactive protein concentrations were observed between groups. In conclusion, the addition of n-3PUFA to a beverage containing whey protein, leucine and carbohydrate ameliorates the increase in muscle soreness and blood concentrations of creatine kinase following eccentric exercise in competitive soccer players.


#9 Movement Patterns of a U-20 National Women's Soccer Team during Competitive Matches: Influence of Playing Position and Performance in the First Half
Reference: Int J Sports Med. 2017 Sep;38(10):747-754. doi: 10.1055/s-0043-110767. Epub 2017 Aug 7.
Authors: Ramos GP, Nakamura FY, Pereira LA, Junior WB, Mahseredjian F, Wilke CF, Garcia ES, Coimbra CC
Summary: The aim of this study was to determine the match locomotor characteristics of a sample of U-20 Brazilian female soccer players. Seven international matches were analyzed during the 2015 U-20 South American Championship, using global positioning technology. During a typical match, fullbacks and forwards covered greater distances in high-intensity running and sprinting than central defenders and midfielders (effect size [ES]=1.42-3.69). In the final 15 min of a game, total and high-intensity running distance and player load were ≈20 to 35% (ES=0.41-3.86) lower than in the first 15 min period for midfielders, fullbacks, forwards, and central defenders. Sprinting, and high-intensity running distances, and the frequency of accelerations >2 m.s-2 immediately after the most intense 5-min period declined in forwards (ES=1.78-2.67), fullbacks (ES=1.96-5.25), midfielders (ES=1.66-3.77), and central defenders (ES=1.50-4.22). Maintaining 'high' levels of activity in the first half resulted in ≈19% reductions in the second half for sprinting distance and frequency of accelerations >2 m.s-2 (ES=0.43 and 0.88), while increases in these locomotor activities were observed in situations with 'low' levels of activity (ES=0.64 and 1.12, for sprinting and accelerations >2 m.s-2, respectively) (within-subject analysis). The data demonstrate that high-intensity efforts are reduced during various phases of international matches and overall activity patterns vary among playing positions. This information could be useful in the development and prescription of sex- and age-specific training regimes.


#10 Sudden Cardiac Death in Professional Soccer Players

Reference: J Am Coll Cardiol. 2017 Sep 12;70(11):1420-1421. doi: 10.1016/j.jacc.2017.07.738.

Authors: Santos-Lozano A, Martin-Hernandez J, Baladron C, Turrado-Sevilla MA, Arraras-Flores A, Villacastin JP, Boraita A, Bueno H, Lucia A.


Australian Football
#1 The Use of Relative Speed Zones in Australian Football: Are We Really Measuring What We Think We Are?
Reference: Int J Sports Physiol Perform. 2017 Sep 5:1-25. doi: 10.1123/ijspp.2017-0148. [Epub ahead of print]
Authors: Murray NB, Gabbett TJ, Townshend AD
Summary: This study aimed to examine the difference between absolute and relative workloads, injury likelihood, and the acute:chronic workload ratio (ACWR) in elite Australian football. Forty-five elite Australian football players from one club participated in this study. Running workloads of players were tracked using Global Positioning System technology, and were categorised using either; (1) absolute, pre-defined speed thresholds, or (2) relative, individualised speed thresholds. Players were divided into three equal groups based on maximum velocity; (1) faster, (2) moderate, or (3) slower. One-week and four-week workloads were calculated, along with the ACWR. Injuries were recorded if they were non-contact in nature and resulted in "time-loss". Faster players demonstrated a significant overestimation of very high-speed running when compared to their relative thresholds (p=0.01, ES=-0.73). Similarly, slower players demonstrated an underestimation of high- (p=0.06, ES=0.55) and very high-speed (p=0.01, ES=1.16) running when compared to their relative thresholds. For slower players, (1) greater amounts of relative very high-speed running had a greater risk of injury than less (RR=8.30, p=0.04), and (2) greater absolute high-speed chronic workloads demonstrated an increase in injury likelihood (RR=2.28, p=0.16), while greater relative high-speed chronic workloads offered a decrease in injury likelihood (RR=0.33, p=0.11). Faster players with a very high-speed ACWR of >2.0 had a greater risk of injury than those between 0.49-0.99 for both absolute (RR=10.31, p=0.09) and relative (RR=4.28, p=0.13) workloads. The individualisation of velocity thresholds significantly alters the amount of very high-speed running performed and should be considered in the prescription of training load.


#2 The Influence of Rotations on Match Running Performance in Female Australian Football Midfielders
Reference: Int J Sports Physiol Perform. 2017 Sep 5:1-22. doi: 10.1123/ijspp.2017-0175. [Epub ahead of print]
Authors: Black GM, Gabbett TJ, Johnston RD, Naughton G, Cole MH, Dawson B
Summary: With female Australian football (AF) gaining popularity, the understanding of match demands is becoming increasingly important. The aim of this study compare running performances of rotated and whole-quarter state level female Australian Football players during match quarters. Twenty-two state-level female AF midfielders wore global positioning system units during 14 games to evaluate activity profiles. The Yo-Yo Intermittent Recovery Test (Level 1[Yo-Yo IR1]) was used as a measure of high-intensity running ability. Each player's data were categorised into either (1) whole-quarter (2) rotation bout 1 (3) rotation bout 2 before being further divided into quartiles. Players were separated into high or low Yo-Yo IR1 groups using a median split based on their Yo-Yo IR1 performance. Short (4-6 minutes), moderate (6-12 minutes) and long (12-18 minutes) on-field bout activity profiles were compared with whole-quarter players. Rotated players covered greater relative-and high-speed distances than whole-quarter players during a number of quartiles (Effect Size: ES, ≥0.44, Likelihood ≥94%). High Yo-Yo IR1 players covered greater relative and high-speed distances than low Yo-Yo IR1 players in rotation period 1. High Yo-Yo IR1 performance allowed players to cover greater relative distances (ES range=0.57-0.88) and high-speed distances (ES range=0.57-0.86) during rotations. No differences were reported between Yo-Yo IR1 groups when players were required to play whole quarters (ES ≤0.26, Likelihood ≤64%). Players who were on-field for short and moderate durations exhibited greater activity profiles than whole-quarter players. Rotated players have greater activity profiles than whole-quarter players. Additionally, superior high-speed running ability results in a greater activity profile than players who possess lower high-speed running ability. The findings also highlight the importance of short-to-moderate (4-12 minute) rotation periods and may be used to increase high-intensity running performances within quarters in female AF players.

Thu

21

Sep

2017

Football is...(#11)

Coaches not only determine the team's tactic, they also influence the intensity of training (if desired).

Wed

20

Sep

2017

Football is...(#10)

How to start off the 2nd half?

Mon

18

Sep

2017

Football is...(#9)

Jump-training needs to involve both directions - vertical and horizontal.

Fri

15

Sep

2017

Football is...(#8)

During different stages of the game or towards the end of the game....

Thu

14

Sep

2017

Latest research in football - week 35 - 2017

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 Resistance training status and effectiveness of low frequency resistance training on upper-body strength and power in highly trained soccer players
Reference: J Strength Cond Res. 2017 Aug 26. doi: 10.1519/JSC.0000000000002202. [Epub ahead of print]
Authors: Hertzog M, Rumpf MC, Hader K
Summary: Soccer is classified as a contact/collision sport with many player-to-player duels. Winning these duels, shielding the ball or fending off an opponent requires upper-body strength and power. Therefore this study aimed, a) to examine the time-related effect of an upper-body RT on maximal strength and power changes in highly trained soccer players, b) to investigate if the resistance-training (RT) status influences these changes throughout a competitive season. Twenty-eight soccer players participated in this study and were divided into an untrained (UG) and a trained (TG) group, according to their RT status. Both groups performed the same upper-body RT once a week, over 30 weeks. Maximal strength (1RM) and maximal power (MP) were assessed before, during and after the competitive season. Both groups significantly improved 1RM and MP over the entire competitive season, with a moderate (TG, 13%) to very large (UG, 21%) magnitude in 1RM and with a small (TG, 8%) to moderate (UG, 13%) magnitude in MP. After the initial 10 weeks of RT, UG presented significant and slightly (1RM) to moderately (MP) greater improvements than TG. For all other time intervals, the between-groups changes in 1RM were rated as similar. For the last 20 weeks of the RT, the change in MP was significantly lower for UG compared to TG. One upper-body RT-session per week will provide sufficient stimulus to enable an almost certain improvement in strength and power throughout a competitive season for all players disregarding their initial RT status.


#2 Fundamental Tactical Principles of Soccer: A Comparison of Different Age Groups
Reference: J Hum Kinet. 2017 Aug 1;58:207-214. doi: 10.1515/hukin-2017-0078. eCollection 2017 Sep.
Authors: Borges PH, Guilherme J, Rechenchosky L, da Costa LCA, Rinadi W
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5548168/pdf/hukin-58-207.pdf
Summary: The fundamental tactical principles of the game of soccer represent a set of action rules that guide behaviours related to the management of game space. The aim of this study was to compare the performance of fundamental offensive and defensive tactical principles among youth soccer players from 12 to 17 years old. The sample consisted of 3689 tactical actions performed by 48 soccer players in three age categories: under 13 (U-13), under 15 (U-15), and under 17 (U-17). Tactical performance was measured using the System of Tactical Assessment in Soccer (FUT-SAT). The Kruskal Wallis, Mann-Whitney U, Friedman, Wilcoxon, and Cohen's Kappa tests were used in the study analysis. The results showed that the principles of "offensive coverage" (p = 0.01) and "concentration" (p = 0.04) were performed more frequently by the U-17 players than the U-13 players. The tactical principles "width and length" (p < 0.05) and "defensive unit" (p < 0.05) were executed more frequently by younger soccer players. It can be concluded that the frequency with which fundamental tactical principles are performed varies between the gaming categories, which implies that there is valuation of defensive security and a progressive increase in "offensive coverage" caused by increased confidence and security in offensive actions.


#3 High Speed Running and Sprinting Profiles of Elite Soccer Players
Reference: J Hum Kinet. 2017 Aug 1;58:169-176. doi: 10.1515/hukin-2017-0086. eCollection 2017 Sep.
Authors: Minano-Espin J, Casais L, Lago-Penas C, Gomez-Ruano MA
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5548164/pdf/hukin-58-169.pdf
Summary: Real Madrid was named as the best club of the 20th century by the International Federation of Football History and Statistics. The aim of this study was to compare if players from Real Madrid covered shorter distances than players from the opposing team. One hundred and forty-nine matches including league, cup and UEFA Champions League matches played by the Real Madrid were monitored during the 2001-2002 to the 2006-2007 seasons. Data from both teams (Real Madrid and the opponent) were recorded. Altogether, 2082 physical performance profiles were examined, 1052 from the Real Madrid and 1031 from the opposing team (Central Defenders (CD) = 536, External Defenders (ED) = 491, Central Midfielders (CM) = 544, External Midfielders (EM) = 233, and Forwards (F) = 278). Match performance data were collected using a computerized multiple-camera tracking system (Amisco Pro®, Nice, France). A repeated measures analysis of variance (ANOVA) was performed for distances covered at different intensities (sprinting (>24.0 km/h) and high-speed running (21.1-24.0 km/h) and the number of sprints (21.1-24.0 km/h and >24.0 km/h) during games for each player sectioned under their positional roles. Players from Real Madrid covered shorter distances in high-speed running and sprint than players from the opposing team (p < 0.01). While ED did not show differences in their physical performance, CD (p < 0.05), CM (p < 0.01), EM (p < 0.01) and F (p > 0.01) from Real Madrid covered shorter distances in high-intensity running and sprint and performed less sprints than their counterparts. Finally, no differences were found in the high-intensity running and sprint distances performed by players from Real Madrid depending on the quality of the opposition.


#4 The Predictors and Determinants of Inter-Seasonal Success in a Professional Soccer Team
Reference: J Hum Kinet. 2017 Aug 1;58:157-167. doi: 10.1515/hukin-2017-0084. eCollection 2017 Sep.
Authors: Kite CS, Nevill A
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5548163/pdf/hukin-58-157.pdf
Summary: The aims of this study were to 1) directly compare the performances of a professional soccer team over three seasons, 2) identify key variables that discriminated between a successful or unsuccessful performance, and 3) identify variables that best predicted success. ANOVA revealed that attempted and completed passes were significantly lower (both p < 0.001) in the most successful season (S1). Additionally, shot effectiveness was significantly less (p < 0.001) in their least successful season (S3) (vs S1 -11.61%; d = 0.735; vs S2 -12.02%; d = 0.760). When the match outcome was considered, they attempted significantly fewer passes when they won (-60.26; p = 0.002; d = -0.729) or drew (-44.87; p = 0.023; d = -0.543) compared to when they lost. The binary logistic regression analysis also retained passing variables. The team should attempt fewer passes, but ensure that more of these passes are completed. With away matches, the effect became more pronounced (β = -0.042, OR = 0.959, p = 0.012). In conclusion, the team should adopt a more direct style of play. They should move the ball into a shooting position with fewer passes and ensure that more shots are on the target.


#5 Effects of Plyometric Training and Beta-Alanine Supplementation on Maximal-Intensity Exercise and Endurance in Female Soccer Players
Reference: J Hum Kinet. 2017 Aug 1;58:99-109. doi: 10.1515/hukin-2017-0072. eCollection 2017 Sep.
Authors: Rosas F, Ramirez-Campillo R, Martinez C, Caniuqueo A, Canas-Jamet R, McCrudden E, Meylan C, Moran J, Nakamura FY, Pereira LA, Loturco I, Diaz D, Izquierdo M
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5548158/pdf/hukin-58-099.pdf
Summary: Plyometric training and beta-alanine supplementation are common among soccer players, although its combined use had never been tested. Therefore, a randomized, double-blind, placebo-controlled trial was conducted to compare the effects of a plyometric training program, with or without beta-alanine supplementation, on maximal-intensity and endurance performance in female soccer players during an in-season training period. Athletes (23.7 ± 2.4 years) were assigned to either a plyometric training group receiving a placebo (PLACEBO, n = 8), a plyometric training group receiving beta-alanine supplementation (BA, n = 8), or a control group receiving placebo without following a plyometric training program (CONTROL, n = 9). Athletes were evaluated for single and repeated jumps and sprints, endurance, and change-of-direction speed performance before and after the intervention. Both plyometric training groups improved in explosive jumping (ES = 0.27 to 1.0), sprinting (ES = 0.31 to 0.78), repeated sprinting (ES = 0.39 to 0.91), 60 s repeated jumping (ES = 0.32 to 0.45), endurance (ES = 0.35 to 0.37), and change-of-direction speed performance (ES = 0.36 to 0.58), whereas no significant changes were observed for the CONTROL group. Nevertheless, compared to the CONTROL group, only the BA group showed greater improvements in endurance, repeated sprinting and repeated jumping performances. It was concluded that beta-alanine supplementation during plyometric training may add further adaptive changes related to endurance, repeated sprinting and jumping ability.


#6 Baseline Mechanical and Neuromuscular Profile of Knee Extensor and Flexor Muscles in Professional Soccer Players at the Start of the Pre-Season
Reference: J Hum Kinet. 2017 Aug 1;58:23-34. doi: 10.1515/hukin-2017-0066. eCollection 2017 Sep.
Authors: Garcia-Garcia O, Serrano-Gomez V, Hernandez-Mendo A, Morales-Sanchez V
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5548152/pdf/hukin-58-023.pdf
Summary: The aim of the study was to determine the mechanical and neuromuscular profile of knee extensor and flexor muscles in professional soccer players at the start of the pre-season, and to calculate percentages for symmetry, as well as examine differences according to the player's positional role. The vastus medialis (VM), vastus lateralis (VL), rectus femoris (RF) and biceps femoris (BF) of 16 professional soccer players were evaluated by means of tensiomyography (TMG) on the first day of the pre-season. A paired-samples t test (p < .05) was used to compare the dominant and non-dominant lower limb. One-way ANOVA was applied, with the positional role as an independent factor. No differences were observed between the dominant and non-dominant leg. The highest degree of symmetry corresponded to the VM (92.5 ± 2.7%), and the lowest to the BF (80.7 ± 10.9%). The positional role was associated with significant differences in some of the variables for the BF, RF and VM, although only the half-relaxation time in the BF and the time to sustain force in the VM differed across all the playing positions considered. TMG was shown to be a useful way of evaluating the neuromuscular characteristics of soccer players at the start of the pre-season, and of establishing baseline values for individual players.


#7 Relationship between Anxiety and Interleukin 10 in Female Soccer Players with and Without Premenstrual Syndrome (PMS)
Reference: Rev Bras Ginecol Obstet. 2017 Aug 28. doi: 10.1055/s-0037-1606244. [Epub ahead of print]
Authors: Foster R, Vaisberg M, Araujo MP, Martins MA, Capel T, Bachi ALL, Bella ZIKJ
Summary: The objective was to investigate the level of anxiety and its relationship with interleukin (IL)-10 (anti inflammatory cytokine that modulates mood swings) in a group of female soccer players. Fifty-two eumenorrheic soccer players were evaluated (age 19.8 ± 4.7 years). The presence of premenstrual syndrome (PMS) and phases of the menstrual cycle were determined by a daily symptom report (DSR) kept for 3 consecutive months. The concentration of cytokine IL-10 was determined from urine samples collected at four moments: at the follicular and luteal phases of the menstrual cycle, and before (pre) and after (post) the simulated game, and it was quantified by flow cytometry (Luminex xMAP - EMD Millipore, Billerica, MA, USA). The level of anxiety was determined through the BAI anxiety questionnaire answered by all athletes at the same time of the urine collection. The Student t-test, analysis of variance (ANOVA) and Pearson correlation with significance level at 5% were used for data analysis.  We showed that the prevalence of PMS among female soccer players is similar to that reported in the literature. In addition, we showed that the group with PMS has a higher level of anxiety compared with group without PMS (p = 0.002). Interleukin-10 analysis in players without PMS revealed that there was a significant decrease in the level of this cytokine before the game during the luteal phase when compared with the follicular phase (p < 0.05). The correlation analysis between IL-10 and anxiety showed a negative correlation post-game in the luteal phase in the group without PMS (p = 0.02; r = -0.50) and a positive correlation post-game in the luteal phase in PMS group (p = 0.04; r = 0.36).  Our results suggest that IL-10 may contribute to reduce anxiety in the group without PMS. This could be attributed to the fact that no IL-10 variation was observed in the group with PMS, which presented higher anxiety symptoms when compared with the group without PMS.


#8 Sprint mechanics return to competition follow-up after hamstring injury on a professional soccer player: A case study with an inertial sensor unit based methodological approach
Reference: J Biomech. 2017 Aug 20. pii: S0021-9290(17)30420-7. doi: 10.1016/j.jbiomech.2017.08.010. [Epub ahead of print]
Authors: Setuain I, Lecumberri P, Izquierdo M
Summary: The present research aimed to describe an inertial unit (IU)-based sprint mechanics evaluation model for assessing players' readiness to return to competition after suffering a grade I hamstring injury. A professional male football player (age 19years; height 177cm; weight 70kg, midfielder, Spanish, 3° Division) with a grade 1 biceps femoris injury was evaluated at pre-season, at return to play after injury and at the end of the competitive season. Sprint mechanics were analyzed via the use of an inertial orientation tracker (Xsens Technologies B.V. Enschede, Netherlands) attached over the L3-L4 region of the subject's lumbar spine. Sprint mechanics such as horizontal components of ground reaction force were assessed in both legs during sprinting actions. Findings and interpretation: Both the coefficient of the horizontal force application (SFV) and the ratio of forces (DRF) applied at increasing velocity were decreased in the injured limb compared with the contralateral healthy limb at the return to play evaluation (73% and 76% reductions, respectively) and returned to symmetrical levels at the end-season evaluation.


#9 The Brazilian World Cup: too hot for soccer?
Reference: Int J Biometeorol. 2017 Aug 25. doi: 10.1007/s00484-017-1425-y. [Epub ahead of print]
Authors: Lucena RL, Steinke ET, Pacheco C, Vieira LL, Betancour MO, Steinke VA
Summary: The main objective of this research was to analyze the climate data for the host cities of the soccer World Cup held in Brazil in June and July 2014. A great deal of criticism was expressed about the Brazilian climate in the national and international press and media in the run-up to the competition, suggesting that the air temperature and relative air humidity would be the main adversaries of the soccer teams, especially those from Europe, during the competition. An analysis of the weather was done at the places and times of each of the 64 matches held. A human thermal comfort index was calculated (discomfort index (DI)) for each of the matches in order to discover the real climatic conditions in the host cities during the 2014 World Cup and their potential influence on the teams and human comfort in general. During the 2014 World Cup, only two matches were played at temperatures above 30 °C, representing a negligible percentage of the total number of matches. The air temperature for over half the matches (53%) was 20-25 °C. The results showed the air temperature and relative humidity data analyzed here both individually and in the form of an index indicate that the World Cup held in Brazil in 2014 did not put any of the players at risk due to extreme heat.



American Football
#1 Prevalence and Impact of Glenoid Augmentation in American Football Athletes Participating in the National Football League Scouting Combine
Reference: Orthop J Sports Med. 2017 Aug 9;5(8):2325967117722945. doi: 10.1177/2325967117722945. eCollection 2017 Aug.
Authors: Knapik DM, Gillespie RJ, Salata MJ, Voos JE
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5555500/pdf/10.1177_2325967117722945.pdf
Summary: Bony augmentation of the anterior glenoid is used in athletes with recurrent shoulder instability and bone loss; however, the prevalence and impact of repair in elite American football athletes are unknown. The purpoas was to evaluate the prevalence and impact of glenoid augmentation in athletes invited to the National Football League (NFL) Scouting Combine from 2012 to 2015. A total of 1311 athletes invited to the NFL Combine from 2012 to 2015 were evaluated for history of either Bristow or Latarjet surgery for recurrent anterior shoulder instability. Athlete demographics, surgical history, imaging, and physical examination results were recorded using the NFL Combine database. Prospective participation data with regard to draft status, games played, games started, and status after the athletes' first season in the NFL were gathered using publicly available databases. Surgical repair was performed on 10 shoulders in 10 athletes (0.76%), with the highest prevalence in defensive backs (30%; n = 3). Deficits in shoulder motion were exhibited in 70% (n = 7) of athletes, while 40% (n = 4) had evidence of mild glenohumeral arthritis and 80% demonstrated imaging findings consistent with a prior instability episode (8 labral tears, 2 Hill-Sachs lesions). Prospectively, 40% (n = 4) of athletes were drafted into the NFL. In the first season after the combine, athletes with a history of glenoid augmentation were not found to be at significant risk for diminished participation with regard to games played or started when compared with athletes with no history of glenoid augmentation or athletes undergoing isolated shoulder soft tissue repair. After the conclusion of the first NFL season, 60% (n = 6 athletes) were on an active NFL roster. Despite being drafted at a lower rate than their peers, there were no significant limitations in NFL participation for athletes with a history of glenoid augmentation when compared with athletes without a history of shoulder surgery or those with isolated soft tissue shoulder repair. Glenohumeral arthritis and advanced imaging findings of labral tearing and Hill-Sachs lesions in elite American football players with a history of glenoid augmentation did not significantly affect NFL participation 1 year after the combine.


#2 Performance and Return to Sport After Clavicle Open Reduction and Internal Fixation in National Football League Players
Reference: Orthop J Sports Med. 2017 Aug 8;5(8):2325967117720677. doi: 10.1177/2325967117720677. eCollection 2017 Aug.
Authors: Jack RA 2nd, Sochacki KR, Navarro SM, McCulloch PC, Lintner DM, Harris JD
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5555514/pdf/10.1177_2325967117720677.pdf
Summary: Clavicle fractures are common injuries in professional football. Surgical fixation of these injuries may lead to decreased nonunion rates, improved shoulder strength, and decreased residual functional impairment. The purpoas of the study was to determine (1) return-to-sport (RTS) rate in National Football League (NFL) players after clavicle fracture open reduction and internal fixation (ORIF), (2) postoperative career length and games per season, (3) pre- and postoperative performance, and (4) postoperative performance compared with control players matched by position, age, years of experience, and performance. Publicly available records were used to identify players who underwent surgical treatment of a clavicle fracture while playing in the NFL. Demographic and performance data were collected for each player, and matched controls were identified. Control and case performance scores were calculated using a standardized scoring system. RTS was defined as playing in 1 NFL game after surgery. Comparisons between case and control groups at preoperative and postoperative time points were made using paired-samples Student t tests. Seventeen surgeries (16 players) were analyzed. Fifteen players (94.1%) were able to RTS in the NFL at a mean 211.3 ± 144.7 days postsurgery; 7 (44%) returned within the same season as their injury and subsequent fixation. The overall rate of a player's remaining in the NFL 1 year after surgery was 88.2%. Players who underwent surgery played in a similar number of games per season and had similar career lengths in the NFL as controls (P > .05). There were no significant (P > .05) differences between cases and matched controls presurgery and preindex. There was no difference (P > .05) in postoperative performance scores or games per season compared with preoperative scores or games per season for any position. Quarterbacks (n = 3, P = .049) and running backs (n = 5, P = .039) had significantly worse postoperative performance scores when compared with postindex matched controls. There is a high rate of RTS in the NFL after clavicle fracture ORIF. Players who underwent clavicle fracture ORIF played in a similar number of games per season and had similar career lengths in the NFL as controls. Quarterbacks and running backs had significantly worse postoperative performance scores when compared with postindex matched controls.


#3 Infographic: Effects of specific injury prevention programmes in football
Reference: Br J Sports Med. 2017 Aug 24. pii: bjsports-2017-098305. doi: 10.1136/bjsports-2017-098305. [Epub ahead of print]
Authors: Thorborg K, Krommes KK, Esteve E, Clausen MB, Bartels EM, Rathleff MS5, Thorborg K


#4 Injuries in Australian Rules Football: An Overview of Injury Rates, Patterns, and Mechanisms Across All Levels of Play
Reference: Sports Health. 2017 Aug 1:1941738117726070. doi: 10.1177/1941738117726070. [Epub ahead of print]
Authors: Saw R, Finch CF, Samra D, Baquie P, Cardoso T, Hope D, Orchard JW
Summary: The nature of Australian rules football (Australian football) predisposes both unique and common injuries compared with those sustained in other football codes. The game involves a combination of tackling, kicking, high-speed running (more than other football codes), and jumping. Two decades of injury surveillance has identified common injuries at the professional level (Australian Football League [AFL]). The objective was to provide an overview of injuries in Australian rules football, including injury rates, patterns, and mechanisms across all levels of play. A narrative review of AFL injuries, football injury epidemiology, and biomechanical and physiological attributes of relevant injuries. The overall injury incidence in the 2015 season was 41.7 injuries per club per season, with a prevalence of 156.2 missed games per club per season. Lower limb injuries are most prevalent, with hamstring strains accounting for 19.1 missed games per club per season. Hamstring strains relate to the volume of high-speed running required in addition to at times having to collect the ball while running in a position of hip flexion and knee extension. Anterior cruciate ligament injuries are also prevalent and can result from contact and noncontact incidents. In the upper limb, shoulder sprains and dislocations account for 11.5 missed games per club per season and largely resulted from tackling and contact. Concussion is less common in AFL than other tackling sports but remains an important injury, which has notably become more prevalent in recent years, theorized to be due to a more conservative approach to management. Although there are less injury surveillance data for non-AFL players (women, community-level, children), many of these injuries appear to also be common across all levels of play. An understanding of injury profiles and mechanisms in Australian football is crucial in identifying methods to reduce injury risk and prepare players for the demands of the game.


#5 Performance and Return to Sport After Forearm Fracture Open Reduction and Internal Fixation in National Football League Players
Reference: Hand (N Y). 2017 Aug 1:1558944717726137. doi: 10.1177/1558944717726137. [Epub ahead of print]
Author: Sochacki KR, Jack RA 2nd, Hirase T, McCulloch PC, Lintner DM, Liberman SR, Harris JD
Summary: Forearm fractures are one of the most common upper extremity injuries requiring surgery in professional football. Surgical fixation of forearm fractures may speed recovery and decrease games missed in football. National Football League (NFL) players who underwent forearm fracture open reduction and internal fixation (ORIF) were identified. Matched controls (position, age, experience, performance) were identified. Control and case performance scores were calculated using a standardized scoring system. Return to sport (RTS) in the NFL was defined as playing in a single NFL game after surgery. Comparisons between case and control groups and preoperative and postoperative time points were made using paired-samples Student t tests. Thirty-six surgeries were analyzed following ORIF. Thirty-three were able to RTS in the NFL at an average of 152.1 + 129.8 days. Controls had a significantly longer NFL career ( P < .001) and played in significantly more games per season ( P = .026) than players who underwent surgery. There was a significant ( P = .013) decrease in games/season for DBs following surgery. No significant difference was seen in postoperative performance scores compared with preoperative scores among any positions, nor in postoperative and postindex performance scores compared with matched controls. There is a high rate of RTS in the NFL following forearm fracture ORIF. Following surgery, players' careers were 1 year shorter and played nearly 2 fewer games per season than matched controls. Games per season following surgery was significantly lower among DBs when compared with presurgery. Postoperative performance scores were not significantly different compared with preoperative and when compared with matched controls.


#6 Sleep-Disordered Breathing and Cardiovascular Correlates in College Football Players
Reference: Am J Cardiol. 2017 Jul 25. pii: S0002-9149(17)31195-5. doi: 10.1016/j.amjcard.2017.07.030. [Epub ahead of print]
Authors: Kim JH, Hollowed C, Irwin-Weyant M, Patel K, Hosny K, Aida H, Gowani Z, Sher S, Gleason P, Shoop JL, Galante A, Clark C, Ko YA, Quyyumi AA, Collop NA, Baggish AL
Summary: This study sought to determine the cardiovascular physiologic correlates of sleep-disordered breathing (SDB) in American-style football (ASF) participants using echocardiography, vascular applanation tonometry, and peripheral arterial tonometry. Forty collegiate ASF participants were analyzed at pre- and postseason time points with echocardiography and vascular applanation tonometry. WatchPAT (inclusive of peripheral arterial tonometry) used to assess for SDB was then performed at the postseason time point. Twenty-two of 40 (55%) ASF participants demonstrated SDB with an apnea-hypopnea index (pAHI) ≥5. ASF participants with SDB were larger (109 ± 20 vs 92 ± 14 kg, p = 0.004) and more likely linemen position players (83% vs 50%, p = 0.03). Compared with those without SDB, ASF participants with SDB demonstrated relative impairments in left ventricular diastolic and vascular function as reflected by lower lateral e' (14 ± 3 vs 17 ± 3 cm/s, p = 0.007) and septal e' (11 ± 2 vs 13 ± 2 cm/s, p = 0.009) tissue velocities and higher pulse wave velocity (5.4 ± 0.9 vs 4.8 ± 0.5 m/s, p = 0.02). In the total cohort, there were significant positive correlations between pAHI and pulse wave velocity (r = 0.42, p = 0.008) and inverse correlations between pAHI and the averaged e' tissue velocities (r = -0.42, p = 0.01). In conclusion, SDB is highly prevalent in youthful collegiate ASF participants and associated with relative impairments in cardiac and vascular function. Targeted efforts to identify youthful populations with SDB, including ASF participants, and implement SDB treatment algorithms, represent important future clinical directives.


#7 Thermoregulatory and Perceptual Effects of a Percooling Garment Worn Underneath an American Football Uniform
Reference: J Strength Cond Res. 2017 Aug 26. doi: 10.1519/JSC.0000000000002207. [Epub ahead of print]
Authors: Keen ML, Miller KC, Zuhl MN
Summary: American football athletes are at the highest risk of developing exertional heat illness (EHI). We investigated whether percooling (i.e., cooling during exercise) garments affected perceptual or physiological variables in individuals exercising in the heat while wearing football uniforms. Twelve males (age=24±4y, mass=80.1±8.5kg, height=182.5±10.4cm) completed this cross-over, counterbalanced study. On day 1, we measured peak oxygen consumption (V[Combining Dot Above]O2). On days 2 and 3, participants wore percooling garments with (ICE) or without (CON) ice packs over the femoral and brachial arteries. They donned a football uniform and completed three, 20-minute bouts of treadmill exercise at ∼50% of peak V[Combining Dot Above]O2 (∼33°C, ∼42% relative humidity) followed by a 10-minute rest period. Ice packs were replaced every 20 minutes. Rating of perceived exertion (RPE), thermal sensation, and thirst sensation were measured before and after each exercise bout. Environmental symptom questionnaire (ESQ) responses and urine specific gravity (Usg) were measured pre-testing and after the last exercise bout. V[Combining Dot Above]O2, change in heart rate (ΔHR), and change in rectal temperature (ΔTrec) were measured every 5 minutes. Sweat rate, sweat volume, and percent hypohydration were calculated. No interactions (F17,187≤1.6, P≥0.1) or main effect of cooling condition (F1,11≤1.4, P≥0.26) occurred for ΔTrec, ΔHR, thermal sensation, thirst, RPE, ESQ, or Usg. No differences between conditions occurred for sweat volume, sweat rate, or percent hypohydration (t11≤0.7, P≥0.25). V[Combining Dot Above]O2 differed between conditions over time (F15,165=3.3, P<0.001); ICE was lower than CON at 30, 55, and 70 minutes (P<0.05). It is unlikely these garments would prevent EHI or minimize dehydration in football athletes.


Australian Football
#1 The relationship between repeated kicking performance and maximal aerobic capacity in elite junior Australian football
Reference: J Strength Cond Res. 2017 Aug 26. doi: 10.1519/JSC.0000000000002220. [Epub ahead of print]
Authors: Joseph J, Woods C, Joyce C
Summary: Australian football (AF) is a physically demanding game, requiring players to engage in a range of anaerobic activities interspersed with prolonged aerobic exercise. Coupled, players have to perform a range of technical skills, the most fundamental of which being to effectively kick (dispose) the ball. The aim of this study was to ascertain the extent to which aerobic capacity influenced kicking performance in AF. Twenty four elite U18 players competing in the same U18 competition performed the Australian Football Kicking test (AFK) three times with the yo-yo IR2 completed twice (between each AFK), with no rest between all three AFKs. Linear mixed models (LMM) reported the extent to which kicking speed and accuracy scores were influenced by the level reached on the yo-yo IR2. Results indicated that players who recorded a higher level on the yo-yo IR2 produced a faster average kicking speed following each AFK (P <0.01), while for all players, kicking speed was faster and more accurate on their dominant kicking leg regardless of score on the yo-yo IR2 (P <0.01). The LMMs also reported that those who maintained kicking speeds following two yo-yo IR2 also had higher competition kicking efficiency than those who reported reduced kicking speeds. These results show that aerobically proficient U18 AF players who attain a relatively higher score on the yo-yo IR2 may be better equipped at preserving their kicking speed. Thus, coaches may wish to integrate both technical and aerobic drills in an attempt to preserve a player's capability to execute ball disposals with a high velocity.

Thu

14

Sep

2017

Football is...(#7)

Being able to master different situations with the ball at a high pace can be decisive.

Wed

13

Sep

2017

Football is...(#6)

When its going up and down the field, make sure your players have enough (repeated) sprint ability in their tank.

Tue

12

Sep

2017

The Functional Movement Screen in Football

The Functional Movement Screen (FMS) was created to evaluate movement pattern quality for athletes as it thought that poor neuromuscular control increases the risk of acute injuries (8).

Based on this idea, the FMS would therefore serve as the basis for more complex movements (21) and consequently would be useful to identify functional movement deficits such as muscular imbalances/asymmetries (30), flexibility deficits (mobility) and balance or stability (5).

If you want to read the full-article you need to click HERE.

Mon

11

Sep

2017

Football is...(#5)

With the UEFA Champions League starting this week, players will face the first “real” congested schedule. In order to be fit for the next match, recovery is key.

Fri

08

Sep

2017

Football is...(#4)

Counterattack done correctly is deadly.

Thu

07

Sep

2017

Latest research in football - week 34 - 2017

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 Including the Copenhagen Adduction Exercise in the FIFA 11+ Provides Missing Eccentric Hip Adduction Strength Effect in Male Soccer Players: A Randomized Controlled Trial
Reference: Am J Sports Med. 2017 Aug 1:363546517720194. doi: 10.1177/0363546517720194. [Epub ahead of print]
Authors: Haroy J, Thorborg K, Serner A, Bjorkheim A, Rolstad LE, Holmich P, Bahr R, Andersen TE
Summary: The FIFA 11+ was developed as a complete warm-up program to prevent injuries in soccer players. Although reduced hip adduction strength is associated with groin injuries, none of the exercises included in the FIFA 11+ seem to specifically target hip adduction strength. The purpose was to investigate the effect on eccentric hip adduction strength of the FIFA 11+ warm-up program with or without the Copenhagen adduction exercise. We recruited 45 eligible players from 2 U19 elite male soccer teams. Players were randomized into 2 groups; 1 group carried out the standard FIFA 11+ program, while the other carried out the FIFA 11+ but replaced the Nordic hamstring exercise with the Copenhagen adduction exercise. Both groups performed the intervention 3 times weekly for 8 weeks. Players completed eccentric strength and sprint testing before and after the intervention. Per-protocol analyses were performed, and 12 players were excluded due to low compliance (<67% of sessions completed). The main outcome was eccentric hip adduction strength (N·m/kg). Between-group analyses revealed a significantly greater increase in eccentric hip adduction strength of 0.29 Nm/kg (8.9%; P = .01) in favor of the group performing the Copenhagen adduction exercise, whereas no within-group change was noted in the group that used the standard FIFA 11+ program (-0.02 N·m/kg [-0.7%]; P = .69). Including the Copenhagen adduction exercise in the FIFA 11+ program increases eccentric hip adduction strength, while the standard FIFA 11+ program does not. Registration: Registration: ISRCTN13731446 (International Standard Randomised Controlled Trial Number registry).


#2 Balancing performance-based expectations with a holistic perspective on coaching: a qualitative study of Swedish women's national football team coaches' practice experiences
Reference: Int J Qual Stud Health Well-being. 2017 Dec;12(1):1358580. doi: 10.1080/17482631.2017.1358580.
Authors: Lindgren EC, Barker-Ruchti N
Summary: The purpose of this study was to explore how an exclusive sample of women's national football team coaches described how they implement careful coaching while facing social and organizational pressure to win medals. The purpose was to consider coaches' negotiations, we drew on Noddings' concept of caring. Using an interpretive research paradigm, we conducted in-depth interviews with five Swedish women's national football team coaches. An abductive approach was used to simultaneously process the theoretical framework of "ethics of care" and the empirical data. The coaches unanimously adopted a holistic perspective to coaching. The coaching strategies they described included promoting players' development, well-being, and sustainable elite performance; listening to the players' voices and engaging in dialogue; and creating a positive environment and promoting fair play. These findings demonstrate that the women coaches, despite performance pressure, adopt caring coaching in the form of Noddings' pedagogical modelling, dialogue, and confirmation strategies, and provide an example of how coaches can adopt caring, holistic, and athlete-centred coaching while working at the highest level of competitive sport and achieving competitive success.


#3 "Which pass is better?" Novel approaches to assess passing effectiveness in elite soccer
Reference: Hum Mov Sci. 2017 Aug 21;55:172-181. doi: 10.1016/j.humov.2017.07.010. [Epub ahead of print]
Authors: Rein R, Raabe D, Memmert D
Summary: Passing behaviour is a key property of successful performance in team sports. Previous investigations however have mainly focused on notational measurements like total passing frequencies which provide little information about what actually constitutes successful passing behaviour. Consequently, this has hampered the transfer of research findings into applied settings. Here we present two novel approaches to assess passing effectiveness in elite soccer by evaluating their effects on majority situations and space control in front of the goal. Majority situations are assessed by calculating the number of defenders between the ball carrier and the goal. Control of space is estimated using Voronoi-diagrams based on the player's positions on the pitch. Both methods were applied to position data from 103 German First division games from the 2011/2012, 2012/2013 and 2014/2015 seasons using a big data approach. The results show that both measures are significantly related to successful game play with respect to the number of goals scored and to the probability of winning a game. The results further show that on average passes from the mid-field into the attacking area are most effective. The presented passing efficiency measures thereby offer new opportunities for future applications in soccer and other sports disciplines whilst maintaining practical relevance with respect to tactical training regimes or game performances analysis.
 

#4 Hip abductor tendinitis after ACL reconstruction with patellar tendon graft in soccer players. A new clinical complication
Reference: Eur J Orthop Surg Traumatol. 2017 Aug 23. doi: 10.1007/s00590-017-2030-9. [Epub ahead of print]
Authors: Mouzopoulos G, Vlachos C, Tsembeli A, Karantzalis L, Vlachos K
Summary: Although ACL reconstruction remains a complex procedure with possible complications, affecting mainly the knee function, but no complications affecting the hip function have been already mentioned in the literature. Here in, we discuss the demographics, clinical course and outcomes of a rare complication such as hip abductors tendinitis, developed in soccer amateur athletes after ACL reconstruction with patellar tendon graft.


#5 Does a one year age gap modify the influence of age, maturation and anthropometric parameters as determinants of performance among youth elite soccer players?
Reference: J Strength Cond Res. 2017 Aug 22. doi: 10.1519/JSC.0000000000002203. [Epub ahead of print]
Authors: Bidaurrazaga-Letona I, Lekue JA, Amado M, Gil SM
Summary: Since age-groups in soccer often comprise children born within a two-year timeframe, characteristics that define the profile of a successful player may not be appropriate for the oldest or youngest players of the same age group. Therefore, this study aimed to determine to what extent performance was influenced by age, maturation and body size in elite soccer players with barely one year age gap. Anthropometry, 15-m sprint test, modified Barrow´s agility test, Yo-Yo intermittent recovery test level 1, countermovement jump, and handgrip test were conducted in players aged twelve and under (n=82, 11.1 ± 0.6 years; Mean ± SD) and between twelve and thirteen (n=79, 12.8 ± 0.6 years; Mean ± SD). A total score of performance, chronological age and age at peak height velocity were calculated. Descriptive statistics, Student's t-tests, and multiple linear regressions were performed. The explained variance in composite score was greater in the older (54%) than in the younger (30%) players. Sum of skinfolds was the primary predictor of 15-m sprint and countermovement jump in the younger group whereas in the older group chronological age and body size appeared as predictors of performance (41%). Body size explained the variance in most tests in older players. In the younger group biological maturity status explained the variance in endurance (35%) and handgrip (59%) tests. In summary, chronological age and sum of skinfolds influenced most tests; however, predictors differed between age groups. These findings highlight the importance of assessing individual differences in young male soccer players regardless of their similarity in age.


#6 The preventive effect of the bounding exercise programme on hamstring injuries in amateur soccer players: the design of a randomized controlled trial
Reference: BMC Musculoskelet Disord. 2017 Aug 22;18(1):355. doi: 10.1186/s12891-017-1716-9.
Authors: Van de Hoef S, Huisstede BMA, Brink MS, de Vries N, Goedhart EA, Backx FJG
Download link: https://bmcmusculoskeletdisord.biomedcentral.com/track/pdf/10.1186/s12891-017-1716-9?site=bmcmusculoskeletdisord.biomedcentral.com
Summary: Hamstring injuries are the most common muscle injury in amateur and professional soccer. Most hamstring injuries occur in the late swing phase, when the hamstring undergoes a stretch-shortening cycle and the hamstring does a significant amount of eccentric work. The incidence of these injuries has not decreased despite there being effective injury prevention programmes focusing on improving eccentric hamstring strength. As this might be because of poor compliance, a more functional injury prevention exercise programme that focuses on the stretch-shortening cycle might facilitate compliance. In this study, a bounding exercise programme consisting of functional plyometric exercises is being evaluated. A cluster-randomized controlled trial (RCT). Male amateur soccer teams (players aged 18-45 years) have been randomly allocated to intervention and control groups. Both groups are continuing regular soccer training and the intervention group is additionally performing a 12-week bounding exercise programme (BEP), consisting of a gradual build up and maintenance programme for the entire soccer season. The primary outcome is hamstring injury incidence. Secondary outcome is compliance with the BEP during the soccer season and 3 months thereafter. Despite effective hamstring injury prevention programmes, the incidence of these injuries remains high in soccer. As poor compliance with these programmes may be an issue, a new plyometric exercise programme may encourage long-term compliance and is expected to enhance sprinting and jumping performance besides preventing hamstring injuries.


#7 Allergies and Exercise-Induced Bronchoconstriction in a Youth Academy and Reserve Professional Soccer Team
Reference: Clin J Sport Med. 2017 Sep;27(5):450-456. doi: 10.1097/JSM.0000000000000393.
Authors: Bougault V, Drouard F, Legall F, Dupont G, Wallaert B
Summary: A high prevalence of respiratory allergies and exercise-induced bronchoconstriction (EIB) has been reported among endurance athletes. This study was designed to analyze the frequency of sensitization to respiratory allergens and EIB in young soccer players. Youth academy and reserve professional soccer team during the seasons 2012 to 2013 and 2013 to 2014. Eighty-five soccer players (mean age: 20 ± 4 years) participated in this study. Players underwent skin prick tests (SPTs) during the seasons 2012 to 2013 and 2013 to 2014. Spirometry and a eucapnic voluntary hyperpnea test were performed on soccer players during the first season 2012 to 2013 (n = 51) to detect EIB. Two self-administered questionnaires on respiratory history and allergic symptoms (European Community Respiratory Health Survey and Allergy Questionnaire for Athletes) were also distributed during both seasons (n = 59). The number of positive SPTs, exercise-induced respiratory symptoms, presence of asthma, airway obstruction, and EIB. Forty-nine percent of players were sensitized to at least one respiratory allergen, 33% reported an allergic disease, 1 player presented airway obstruction at rest, and 16% presented EIB. Factors predictive of EIB were self-reported exercise-induced symptoms and sensitization to at least 5 allergens. Questioning players about exercise-induced respiratory symptoms and allergies as well as spirometry at the time of the inclusion medical checkup would improve management of respiratory health of soccer players and would constitute inexpensive preliminary screening to select players requiring indirect bronchial provocation test or SPTs.


#8 Recent and Long-Term Soccer Heading Exposure Is Differentially Associated With Neuropsychological Function in Amateur Players
Reference: J Int Neuropsychol Soc. 2017 Aug 22:1-9. doi: 10.1017/S1355617717000790. [Epub ahead of print]
Authors: Levitch CF, Zimmerman ME, Lubin N, Kim N, Lipton RB, Stewart WF, Kim M, Lipton ML
Summary: The present study examined the relative contribution of recent or long-term heading to neuropsychological function in amateur adult soccer players. Soccer players completed a baseline questionnaire (HeadCount-12m) to ascertain heading during the prior 12 months (long-term heading, LTH) and an online questionnaire (HeadCount-2w) every 3 months to ascertain heading during the prior 2 weeks (recent heading, RH). Cogstate, a battery of six neuropsychological tests, was administered to assess neuropsychological function. Generalized estimating equations were used to test if LTH or RH was associated with neuropsychological function while accounting for the role of recognized concussion. A total of 311 soccer players completed 630 HeadCount-2w. Participants had an average age of 26 years. Participants headed the ball a median of 611 times/year (mean=1,384.03) and 9.50 times/2 weeks (mean=34.17). High levels of RH were significantly associated with reduced performance on a task of psychomotor speed (p=.02), while high levels of LTH were significantly associated with poorer performance on tasks of verbal learning (p=.03) and verbal memory (p=.04). Significantly better attention (p=.02) was detectable at moderately high levels of RH, but not at the highest level of RH. One hundred and seven (34.4%) participants reported a lifetime history of concussion, but this was not related to neuropsychological function and did not modify the association of RH or LTH with neuropsychological function. High levels of both RH and LTH were associated with poorer neuropsychological function, but on different domains. The clinical manifestations following repetitive exposure to heading could change with chronicity of exposure. (JINS, 2017, 23, 1-9).


#9 Variability of Metabolic Power Data in Elite Soccer Players During Pre-Season Matches
Reference: J Hum Kinet. 2017 Aug 1;58:233-245. doi: 10.1515/hukin-2017-0083. eCollection 2017 Sep.
Authors: Hoppe MW, Baumgart C, Slomka M, Polglaze T, Freiwald J
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5548171/pdf/hukin-58-233.pdf
Summary: This study aimed to determine the within-subject variability of GPS-derived metabolic power data in elite soccer players across several pre-season matches and compare the variability of high metabolic power, velocity, acceleration and deceleration running. Additionally, differences in metabolic power data among playing positions and relationships with various physical abilities were also investigated. Metabolic power data from 12 outfield starting players competing in the German Bundesliga were collected during five pre-season matches using GPS-technology (10 Hz). The players were also tested for speed, agility, power and intermittent endurance. Variability of global metabolic power data such as energy expenditure (CV = 2.2-7.0%) was lower than that for high-intensity including time ≥20 W·kg-1 (CV = 14.0-26.2%). Variability of high metabolic power (≥20 W·kg-1; CV = 14.1 ± 3.5%) was comparable to that of high velocity (≥15.5 km·h-1; CV = 17.0 ± 6.2%), acceleration (≥3 m·s-2; CV = 11.1 ± 5.1%) and deceleration running (≤-3 m·s-2; CV = 11.9 ± 4.5%) (p > 0.05, ES < 0.2). Defenders had a largely higher overall energy expenditure than midfielders and attackers (p < 0.01, ES > 0.6). Overall energy expenditure and cost were largely to very largely correlated with 5 m speed and 22 m agility sprint time and counter movement jump height (r = -0.70-0.69, p < 0.05). The detected variability indicates that global GPS-derived metabolic power data in elite soccer players from a single preseason match should be preferably used for practical applications. Contrary, high-intensity indicators should be interpreted cautiously and repeated match observations are recommended to establish meaningful high-intensity profiles of the players. Differences among playing positions and relationships with explosive physical abilities indicate that metabolic power analyses can provide new insights into the mechanics and energetics of soccer.


#10 Evaluation of the Illinois Change of Direction Test in Youth Elite Soccer Players of Different Age
Reference: J Hum Kinet. 2017 Aug 1;58:215-224. doi: 10.1515/hukin-2017-0079. eCollection 2017 Sep.
Authors: Negra Y, Chaabene H, Amara S, Jaric S, Hammami M, Hachana Y
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5548169/pdf/hukin-58-215.pdf
Summary: Change of direction ability is an essential pre-requisite in team sports athletes. The Illinois change of direction test has been routinely used for testing change of direction ability in soccer players. The aim of the present study was to evaluate the Illinois change of direction test in young elite soccer players in terms of its reliability, usefulness and relationship with body size. A total of one hundred and ninety-four male, national-level soccer players were recruited. They were classified into four age groups (U-8, U-10, U-12 and U-14). Participants were tested using the Illinois change of direction test twice, and basic indices of body size were obtained. The Illinois change of direction scores showed high relative and absolute reliability in all age groups (all intraclass correlation coefficients were >0.91, and the standard error of measurement was <5%). The usefulness analysis showed that the Illinois change of direction test could detect small changes in performance in the U-10 and U-12 groups. However, it could only detect moderate changes in performance in the U-8 and U-14 groups. Although the Illinois change of direction test detected significant performance differences among groups, scores were not significantly related to body size (-0.30<r<0.15; p > 0.05). Taking into account the test's high reliability and the appropriate level of usefulness, these results might support the use of the Illinois change of direction test as a standard measure for quantifying change of direction ability in young soccer players.


American Football
#1 Perceived Wellness Associated With Practice And Competition In Ncaa Division I Football Players
Reference: J Strength Cond Res. 2017 Aug 15. doi: 10.1519/JSC.0000000000002169. [Epub ahead of print]
Authors: Wellman AD, Coad SC, Flynn PJ, Siam TK, McLellan CP.
Summary: The present study assessed the influence of movement demands resulting from weekly practice sessions and games, on perceived wellness measurements taken post-game (Sunday) and 48 hours pre-game (Thursday) throughout the in-season period in National Collegiate Athletic Association (NCAA) division I football players. Thirty players were monitored using GPS receivers (Catapult Innovations OptimEye S5, Melbourne, Australia) during 12 games and 24 in-season practices. Movement variables included low-intensity distance, medium-intensity distance, high-intensity distance, sprint distance, total distance, player load, and acceleration and deceleration distance. Perceived wellness, including fatigue, soreness, sleep quality and quantity, stress, and mood, was examined using a questionnaire on a 1-5 Likert scale. Multi-level mixed linear regressions determined the differential effects of movement metrics on perceived wellness. Post-hoc tests were conducted to evaluate the pair-wise differentials of movement and significance for wellness ratings. Notable findings included significantly (p<0.05) less player load, low-intensity distance, medium-intensity distance, high-intensity distance, total distance, and acceleration and deceleration distance at all intensities, in those reporting more favorable (4-5) ratings of perceived fatigue and soreness on Sunday. Conversely, individuals reporting more favorable Sunday perceived stress ratings demonstrated significantly (p<0.05) higher player load, low-intensity and medium-intensity distance, total distance, low-intensity and medium-intensity deceleration distance, and acceleration distance at all intensities than individuals reporting less favorable (1-2) perceived stress ratings. Data from the present study provide a novel investigation of perceived wellness associated with college football practice and competition. Results support the use of wellness questionnaires for monitoring perceived wellness in NCAA division I college football players.


#2 Maximum distance and high speed distance demands by position in NCAA division I collegiate football games
Reference: J Strength Cond Res. 2017 Jul 5. doi: 10.1519/JSC.0000000000002105. [Epub ahead of print]
Authors: Sanders GJ, Roll B, Peacock CA
Summary: The purpose of the study was to quantify the average and maximum distances traveled by NCAA division I football athletes during competitive games. Utilizing global positioning system (GPS) devices (Catapult Sports), total and low, moderate and high speed distances were quantified by each position. Understanding maximal workloads can enhance conditioning practice periodization protocols. A total of 40 football athletes were included in the analysis. For the data to be included, athletes were required to participate in ≥ 75% of the offensive or defensive snaps for any given game. There was a total of 286 data downloads from 13 different games for eight different football positions. Data was calculated and compared by offensive and defensive position to establish the mean, standard deviation and maximum distances (m) traveled during competitive games. A total maximum distance range (Max Range) was established to account for athletes that accumulated in-game total distances greater than the M + 1SD for each position. A percent was also calculated to highlight how often athletes accumulated distance workloads in the Max Range. One-way ANOVA revealed there was a main effect of football position for all distance variables (p ≤ 0.001). Regardless of position, 12.0-16.7% of the time athletes accumulated in-game total distances in the Max Range. Conditioning and practice periodization protocols for distance should be position-specific or individualized to avoid under or over conditioning. Additionally, utilizing a Max Range for distance can help ensure athletes are achieving distance workloads that are similar to the demands of a competitive game.


#3 Movement Demands And Perceived Wellness Associated With Pre-Season Training Camp In Ncaa Division I College Football Players
Reference: J Strength Cond Res. 2017 Jul 5. doi: 10.1519/JSC.0000000000002106. [Epub ahead of print]
Authors: Wellman AD, Coad SC, Flynn PJ, McLellan CP, Climstein M
Summary: The aims of the present study were to examine the movement demands of pre-season practice in National Collegiate Athletic Association (NCAA) division I college football players using portable global positioning system (GPS) technology and to assess perceived wellness associated with pre-season practice to determine if GPS-derived variables from the preceding day influence perceived wellness the following day. Twenty-nine players were monitored using GPS receivers (Catapult Innovations, Melbourne, Australia) during 20 pre-season practices. Individual observations (n=550) were divided into offensive and defensive position groups. Movement variables including low-, medium-, high-intensity, and sprint distance, player load, and acceleration and deceleration distance were assessed. Perceived wellness ratings (n=469) were examined using a questionnaire which assessed fatigue, soreness, sleep quality, sleep quantity, stress, and mood. A one-way ANOVA for positional movement demands, and multi-level regressions for wellness measures were used, followed by post-hoc testing to evaluate the relational significance between categorical outcomes of perceived wellness scores and movement variables. Results demonstrated significantly (p<0.05) greater total, high-intensity, and sprint distance, along with greater acceleration and deceleration distances for the DB and WR position groups compared to their respective offensive and defensive counterparts. Significant (p<0.05) differences in movement variables were demonstrated for individuals who responded more or less favorably on each of the six factors of perceived wellness. Data from the present study provide novel quantification of the position-specific physical demands and perceived wellness associated with college football pre-season practice. Results support the use of position-specific training and individual monitoring of college football players.


#4 ACTN3 R577X Polymorphism Is Associated With the Incidence and Severity of Injuries in Professional Football Players
Reference: Clin J Sport Med. 2017 Aug 16. doi: 10.1097/JSM.0000000000000487. [Epub ahead of print]
Authors: Myosotis M, Sarah V, Claudia C, Francesco P, Paolo C, Xu Y, Nir E, Calo CM
Summary: The ACTN3 R577X gene variant results in the absence of the α-actinin-3 protein in ∼18% of humans worldwide and has been associated with athletic performance and increased susceptibility to eccentric muscle damage. The aim of this study was to investigate the association between ACTN3 R577X variant and indirect muscle disorders/injuries in professional football players. Two hundred fifty-seven male professional Italian football players (from Serie A, Primavera, Allievi, and Giovanissimi; age = 21.2 ± 5.3 years) and 265 nonathletic controls were recruited for the study. Genomic DNA was extracted using a buccal swab, and the ACTN3 R577X genotype was performed using a PCR method. Structural-mechanical injuries and functional muscle disorders were collected from a subgroup of 169 football players during the period of 2009 to 2014. We hypothesized that the 577XX genotype would be associated with higher predisposition to muscle injuries (compared with the other genotypes). ACTN3 XX (α-actinin-3 deficiency) players had 2.66 higher odds for an injury incidence than their ACTN3 RR counterparts (95% confidence interval [CI]: 1.09-6.63, P = 0.02), whereas RX and RR players had similar injury incidence. Furthermore, ACTN3 XX players had 2.13 higher odds for having a severe injury compared with their RR counterparts (95% CI: 1.25-3.74, P = 0.0054), whereas RX individuals had 1.63 higher odds for having a severe injury compared with the RR players (95% CI: 1.10-2.40, P = 0.015). The ACTN3 R577X polymorphism is associated with the incidence and severity of muscle injuries in professional football players; players with the ACTN3 577XX genotype have higher odds of having muscle injuries than their RR counterparts.Discovering the complex relationship between gene variants and muscle injuries may assist coaches, physiologists, and the medical community to development tailored injury prevention program for football players, which could provide a new edge for successful competition.


#5 Epidemiology of Injuries Identified at the NFL Scouting Combine and Their Impact on Performance in the National Football League: Evaluation of 2203 Athletes From 2009 to 2015
Reference: Orthop J Sports Med. 2017 Jul 24;5(7):2325967117708744. doi: 10.1177/2325967117708744. eCollection 2017 Jul.
Authors: Beaulieu-Jones BR, Rossy WH, Sanchez G, Whalen JM, Lavery KP, McHale KJ, Vopat BG, Van Allen JJ, Akamefula RA, Provencher MT
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5529031/pdf/10.1177_2325967117708744.pdf
Summary: At the annual National Football League (NFL) Scouting Combine, the medical staff of each NFL franchise performs a comprehensive medical evaluation of all athletes potentially entering the NFL. Currently, little is known regarding the overall epidemiology of injuries identified at the combine and their impact on NFL performance. The purpose was to determine the epidemiology of injuries identified at the combine and their impact on initial NFL performance. All previous musculoskeletal injuries identified at the NFL Combine from 2009 to 2015 were retrospectively reviewed. Medical records and imaging reports were examined. Game statistics for the first 2 seasons of NFL play were obtained for all players from 2009 to 2013. Analysis of injury prevalence and overall impact on the draft status and position-specific performance metrics of each injury was performed and compared with a position-matched control group with no history of injury or surgery. A total of 2203 athletes over 7 years were evaluated, including 1490 (67.6%) drafted athletes and 1040 (47.2%) who ultimately played at least 2 years in the NFL. The most common sites of injury were the ankle (1160, 52.7%), shoulder (1143, 51.9%), knee (1128, 51.2%), spine (785, 35.6%), and hand (739, 33.5%). Odds ratios (ORs) demonstrated that quarterbacks were most at risk of shoulder injury (OR, 2.78; P = .001), while running backs most commonly sustained ankle (OR, 1.39; P = .040) and shoulder injuries (OR, 1.55; P = .020) when compared with all other players. Ultimately, defensive players demonstrated a greater negative impact due to injury than offensive players, with multiple performance metrics significantly affected for each defensive position analyzed, whereas skilled offensive players (eg, quarterbacks, running backs) demonstrated only 1 metric significantly affected at each position. The most common sites of injury identified at the combine were (1) ankle, (2) shoulder, (3) knee, (4) spine, and (5) hand. Overall, performance in the NFL tended to worsen with injury history, with a direct correlation found between injury at a certain anatomic location and position of play. Defensive players tended to perform worse compared with offensive players if injury history was present.


Australian Football
#1 Concussion Incidence and Recurrence in Professional Australian Football Match-Play: A 14-Year Analysis
Reference: J Sports Med (Hindawi Publ Corp). 2017;2017:2831751. doi: 10.1155/2017/2831751. Epub 2017 Jul 19.
Authors: Gibbs N, Watsford M
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5540267/pdf/JSM2017-2831751.pdf
Summary: Concussion incidence rates in professional Australian football may be underreported due to the injury classification definition. A myriad of factors contribute to concussion risk; however, there is limited long-term surveillance in Australian football. This study analysed concussion in one Australian football team over an extended period. Match-play concussion injuries in one team (n = 116 participants) were diagnosed and treated by the team physician over 14 years. Analysis of factors related to concussion including matches played, time of day and season, and return to play provided an insight into occurrence and recurrence rates. 140 concussions were recorded (17.6 per 1000 player match hours). A strong relationship was evident between matches played and concussion incidence (r = 0.70) and match conditions did not negatively affect the concussion rate. Whether an athlete returned to play in the same match or suffered a loss-of-consciousness concussion (p = 0.84), their ensuing rate of concussion was not affected. Concussion in professional Australian football was related to the number of matches played. Further, neither previous incidence nor loss of consciousness affected future concussion risk. This study provides ecologically valid evidence of the concussion incidence rate in professional Australian football and has implications for the management of athletes sustaining concussion injuries.

Thu

07

Sep

2017

Football...(#3)

Sprinting in football is an important activity, here are some crucial information.

Wed

06

Sep

2017

Football is...(#2)

High-intensity running for footballers - one suggestion.

Tue

05

Sep

2017

Football is...(#1)

Just in case there were some crucial set-pieces for some teams in the World Cup Qualifiers...

Fri

25

Aug

2017

Latest research in football - week 33 - 2017

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 Inhaled Salbutamol on Sport-Specific Fitness of Non-Asthmatic Football Players
Reference: Acta Med Iran. 2017 May;55(5):324-332.
Authors: Halabchi F, Abarashi M, Mansournia MA, Seifbarghi T
Download link: acta.tums.ac.ir/index.php/acta/article/download/5850/4939
Summary: In this article, we investigated the effectiveness of inhaled salbutamol withtherapeutic dose on the sport-specific performance of non-asthmatic young football players. In a double-blinded, randomised placebo controlled trial with 2-treatment, 2-period crossover design, twenty participants who were non-asthmatic junior professional football players were randomly allocated to two groups. Fifteen minutes before sport-specific fitness testing, each group randomly received 2 inhalations (200 micrograms) of salbutamol or placebo, respectively. After 1 week wash-out period, each participant has tested again, this time with the alternative inhaler. The primary outcomes were the differences between salbutamol and placebo groups in six tests of 7×30-m repeated sprint, Loughborough soccer dribbling, vertical jump, agility, Loughborough soccer passing, 20-m multistage shuttle run. A total of twenty players did two test batteries completely. There was no significant difference between salbutamol and placebo users in the tests [Treatment effect (CI95%); 7×30 sprint: -2.4 (-7.6-2.9), dribbling: -3.8 (-12.2-4.5), vertical jump: -1.2 (-3.7-1.3), agility: -0.4 (-0.9-0.1), passing: 0.2 (-12-12.4), shuttle run distance: -112 (-503.2-279.2)]. Furthermore, no period or carry-over effects were detected. It seems that single therapeutic dose of inhaled salbutamol (200 micrograms) does not appear to improve football related performance.


#2 Heading for trouble: is dementia a game changer for football?
Reference: Br J Sports Med. 2017 Jul 20. pii: bjsports-2017-097627. doi: 10.1136/bjsports-2017-097627. [Epub ahead of print]
Authors: Rutherford A, Stewart W, Bruno D


#3 Infographics: Injury prevention exercise programmes: what are the perceptions of programme deliverers in the academy football setting?
Reference: Br J Sports Med. 2017 Jul 22. pii: bjsports-2017-097774. doi: 10.1136/bjsports-2017-097774. [Epub ahead of print]
Authors: Bekker S, Finch CF, O Brien J


#4 Fixture congestion modulates post-match recovery kinetics in professional soccer players
Reference: Res Sports Med. 2017 Aug 10:1-13. doi: 10.1080/15438627.2017.1365296. [Epub ahead of print]
Authors: Lundberg TR, Weckstrom K
Summary: This study examined the influence of fixture congestion on physical performance and biochemical variables in professional male footballers. After 3 competitive matches within a week (3M cycle), 16 players underwent blood sampling and field testing 72 h after the last match. The same tests were performed after a regular 1 match-week cycle (1M cycle). The 1M vs. 3M change scores were compared between Congested (high match exposure) and non-selected Control players. The change score in muscle soreness was greater (effect size 1.0; CI 0.0-1.9) in the Congested players than Controls, indicating a possible negative effect of fixture congestion. There were no effects on sprint and jump performance. The change in plasma (P)-Urea was greater in Congested players than controls (effect size 1.3; CI 0.3-2.2). The effects on other blood variables were either non-existing/trivial, or unclear. Altogether, physical fitness and immune function were not compromised by match congestion, yet some indices of physiological stress and muscle damage were still evident.


#5 Patellar tendinopathy in young elite soccer- clinical and sonographical analysis of a German elite soccer academy
Reference: BMC Musculoskelet Disord. 2017 Aug 8;18(1):344. doi: 10.1186/s12891-017-1690-2.
Authors: Bode G, Hammer T, Karvouniaris N, Feucht MJ, Konstantinidis L, Sudkamp NP, Hirschmuller A
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5549401/pdf/12891_2017_Article_1690.pdf
Summary: The prevalence of patellar tendinopathy is elevated in elite soccer compared to less explosive sports. While the burden of training hours and load is comparably high in youth elite players (age < 23 years), little is known about the prevalence of patellar tendinopathy at this age. There is only little data available on the influence of age, the amount of training, the position on the field, as well as muscular strength, range of motion, or sonographical findings in this age group. The purpose of the present study was to examine the above-mentioned parameters in all age groups of a German youth elite soccer academy. One hundred nineteen male youth soccer players (age 15,97 ± 2,24 years, height 174, 60 ± 10,16 cm, BMI 21, 24 ± 2,65) of the U-13 to U-23 teams were part of the study. Data acquisition included sport specific parameters such as footwear, amount of training hours, leg dominance, history of tendon pathologies, and clinical examination for palpatory pain, indurations, muscular circumference, and range of motion. Subjective complaints were measured with the Victorian Institute of Sport Assessment Patellar (VISA-P) Score. Furthermore, sonographical examinations (Aplio SSA-770A/80; Toshiba, Tokyo, Japan) with 12-MHz multifrequency linear transducers (8-14 MHz) of both patellar tendons were performed with special emphasis on hyper- and hypo echogenic areas, diameter and neovascularization. The prevalence of patellar tendinopathies was 13.4%. Seventy-five percent of the players complained of pain of their dominant leg with onset of pain at training in 87.5%. The injured players showed a medium amount of 10.34 ± 3.85 training hours and a medium duration of symptoms of 11.94 ± 18.75 weeks. Two thirds of players with patellar tendinopathy were at the age of 15-17 (Odds ratio 1.89) while no differences between players of the national or regional league were observed. In case of patellar tendinopathy, VISA-P was significantly lower in comparison to healthy players (mean ± SD 76.80 ± 28.56 points vs. 95.85 ± 10.37). The clinical examination revealed local pain at the distal patella, pain at stretching, and thickening of the patellar tendon (p = 0.02). The mean tendon diameter measured 2 cm distally to the patella was 4.10 ± 0.68 mm with a significantly increased diameter of 0.15 mm in case of an underlying tendinopathy (p = 0.00). The incidence of hypo-echogenic areas and neovascularizations was significantly elevated in players with patellar tendon syndrome (PTS) (p = 0.05). The prevalence of patellar tendinopathy in youth elite soccer is relatively high in comparison to available data of adult players. Especially players at the age of 15 to 17 are at considerable risk. Tendon thickening, hypo-echogenic areas, and neovascularization are more common in tendons affected by PTS.


#6 The Effects of Maturation on Measures of Asymmetry During Neuromuscular Control Tests in Elite Male Youth Soccer Players
Reference: Pediatr Exerc Sci. 2017 Aug 8:1-23. doi: 10.1123/pes.2017-0081. [Epub ahead of print]
Authors: Read PJ, Oliver JL, Myer GD, De Ste Croix MBA, Lloyd RS
Summary: Asymmetry is a risk factor for male youth soccer players. There is a paucity of data confirming the presence of asymmetry using practically viable screening tasks in players at different stages of maturation. A cross sectional sample (N = 347) of elite male youth soccer players who were either (pre-, circa- or post-peak height velocity (PHV)) completed the following single leg assessments: Y-Balance anterior reach (Y-Bal); hop for distance (SLHD); 75% hop and stick (75%Hop) and countermovement jumps (SLCMJ). SLCMJ landing force asymmetry was higher in both circa and post-PHV groups, (p < 0.001; d = 0.41 - 0.43). 75%Hop landing force asymmetries were also highest in circa PHV players but between group comparisons were not statistically significant and effect sizes were small. SLHD and Y-Bal asymmetries reduced with maturation; however, no group differences were significant, with small to trivial effect sizes (d = ≤ 0.25). Stage of maturation did not have a profound effect on asymmetry. Between-limb differences in functional performance seem to be established in early childhood; thus, targeted interventions to reduce this injury risk factor should commence in pre-PHV athletes and be maintained throughout childhood and adolescence to ensure asymmetry does not increase.


#7 Characteristics of the Foot Static Alignment and the Plantar Pressure Associated with Fifth Metatarsal Stress Fracture History in Male Soccer Players: a Case-Control Study
Reference: Sports Med Open. 2017 Dec;3(1):27. doi: 10.1186/s40798-017-0095-y. Epub 2017 Aug 7.
Authors: Matsuda S, Fukubayashi T, Hirose N
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5545985/pdf/40798_2017_Article_95.pdf
Summary: There is a large amount of information regarding risk factors for fifth metatarsal stress fractures; however, there are few studies involving large numbers of subjects. This study aimed to compare the static foot alignment and distribution of foot pressure of athletes with and without a history of fifth metatarsal stress fractures. The study participants comprised 335 collegiate male soccer players. Twenty-nine with a history of fifth metatarsal stress fractures were in the fracture group and 306 were in the control group (with subgroups as follows: 30 in the fracture foot group and 28 in the non-fracture group). We measured the foot length, arch height, weight-bearing leg-heel alignment, non-weight-bearing leg-heel alignment, forefoot angle relative to the rearfoot, forefoot angle relative to the horizontal axis, and foot pressure. The non-weight-bearing leg-heel alignment was significantly smaller and the forefoot angle relative to the rearfoot was significantly greater in the fracture foot group than in the control foot group (P = 0.049 and P = 0.038, respectively). With regard to plantar pressure, there were no significant differences among the groups. Midfield players had significantly higher rates of fifth metatarsal stress fracture in their histories, whereas defenders had significantly lower rates (chi-square = 13.2, P < 0.05). There were no significant differences in the frequency of fifth metatarsal stress fractures according to the type of foot (kicking foot vs. pivoting foot) or the severity of ankle sprain. Playing the midfield position and having an everted rearfoot and inverted forefoot alignment were associated with fifth metatarsal stress fractures. This information may be helpful for preventing fifth metatarsal stress fracture recurrence. More detailed load evaluations and a prospective study are needed in the future.


#8 The psycho-hormonal influence of anaerobic fatigue on semi-professional female soccer players
Reference: Physiol Behav. 2017 Aug 4;180:8-14. doi: 10.1016/j.physbeh.2017.07.031. [Epub ahead of print]
Authors: Broodryk A, Pienaar C, Edwards D, Sparks M
Summary: Globally it is assumed that high-intensity activities are the general cause of fatigue experienced during a soccer match. However, little is known about the hormonal and psychological effects of fatigue due to these activities on semi-professional female soccer players. Forty-seven female players (22.0±2.7y) from a tertiary education institution volunteered for the study. Their cortisol values (saliva sample), anxiety [Spielberger State-trait anxiety inventory questionnaire (STAI)] and mood scores [Incredible Short Profile of Mood states questionnaire (ISP)] were taken an hour and immediately prior to, and 15min after an anaerobic fatiguing test (AFT). During the AFT, subjects completed a 5-m multiple shuttle run test and their HRmax, blood lactate (BLa-) and rate of perceived exertion (RPE) taken afterwards. Anxiety scores were divided into three categories and mood scores into the Total Mood Disturbances (TMD) and six subscales. The results indicated an increase in cortisol, psychological fatigue and TMD from baseline and/or pre- to post-AFT (p<0.05). Vigour and confusion decreased from baseline and/or pre- to post-AFT (p<0.05). A relationship was seen between state-anxiety and TMD (r≥0.63, p<0.05) at all three time points, as well as between state-anxiety and HRmax (r=0.37, p=0.03). Cortisol and RPE (r=-0.34, p=0.03) demonstrated a correlation post-AFT. This is the first study to evaluate the effects of anaerobic fatigue on the hormonal and psychological states of female soccer players. The results suggest that an AFT can be perceived as a physiological and psychological stressor by female players, hence has the ability to influence performance. Altering a player's awareness and anaerobic fitness level might therefore influence both the hormonal and psychological consequences of the stressor, subsequently reducing the experience of fatigue and thereby enhancing performance.


#9 Pubertal development of body size and soccer-specific functional capacities in adolescent players
Reference: Res Sports Med. 2017 Aug 17:1-16. doi: 10.1080/15438627.2017.1365301. [Epub ahead of print]
Authors: Carvalho HM, Lekue JA, Gil SM, Bidaurrazaga-Letona I
Summary: Pubertal growth in body size and functional capacities were examined in adolescent soccer players (n = 33). The average age at baseline was 10.9 (9.8-11.8 years). Peak height velocity (PHV) and growth curves for body mass and functional performance (countermovement jump, 15-m sprint, agility and Yo-Yo intermittent recovery test - level 1) were determined with Bayesian multilevel models. Estimates for PHV and age at PHV were 8.1 cm/year (95% credible interval: 4.2-18.5 cm/year) and 12.9 years (95% credible interval: 11.8-15.5 years), respectively. Peak body mass velocity occurred 0.48 year after PHV. Jump performance maximum velocity occurred about 2 years after PHV and peak sprint performance maximum velocity was coincident with PHV. Agility and intermittent endurance run performance showed a quadratic trend of improvement of performance, starting to level off at about 3-4 years after PHV. The modelling procedures were efficient to determine pubertal growth curves aligned for chronological age and age at PHV, considering individual differences in maturation when interpreting the development of performance in youth soccer.


#10 Effect of Changes in Artificial Turf on Sports Injuries in Male University Soccer Players
Reference: Orthop J Sports Med. 2017 Aug 2;5(8):2325967117719648. doi: 10.1177/2325967117719648. eCollection 2017 Aug.
Authors: Fujitaka K, Taniguchi A, Kumai T, Otuki S, Okubo M, Tanaka Y
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5544152/pdf/10.1177_2325967117719648.pdf
Summary: Studies comparing the types and severity of trauma and injuries caused by different types of field surfaces have been conducted. However, there have been no studies on sports injuries caused by temporal deterioration of long-pile artificial turf fields and related decreases in the rubber chip and silica sand infill. The purpose was to investigate the influence of an artificial turf field on sports injuries in a university soccer team. A total of 397 male soccer players who were members of a single university soccer team were surveyed over a 12-year period, from April 2003 to March 2015. During this period, the team played for 4 years on a soil field (2003-2006) and 8 years on artificial turf (2007-2014). We analyzed the effect of changes in the artificial turf on the incidence rate of sports injuries (injury rate per 1000 athlete-exposures). We calculated the incidence rate of injuries sustained by the team and compared the results for each year of the study. After conversion of the field to artificial turf, there was a significant increase in the incidence of upper extremity trauma (P < .05). There was a significant increase in lower extremity sprains from 2007 to 2008, 1 year after the conversion from soil to artificial turf (P < .05). Analysis of the incidence of lower extremity muscle strain indicated that although the injury rate increased progressively, it decreased significantly after the insertion of additional rubber chips in 2014 (P < .05). After conversion to artificial turf, there was a significant increase in the incidence of upper extremity trauma. After the refurbishing with additional rubber chips, the incidence of lower extremity muscle strain significantly declined. When analyzing measures that could prevent sports injuries related to soccer, it is necessary to take into consideration the changes that occur to the artificial turf over time.


#11 The influence of speed abilities and technical skills in early adolescence on adult success in soccer: A long-term prospective analysis using ANOVA and SEM approaches
Reference: PLoS One. 2017 Aug 14;12(8):e0182211. doi: 10.1371/journal.pone.0182211. eCollection 2017.
Authors: Honer O, Leyhr D, Kelava A
Download link: http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0182211&type=printable
Summary: Several talent development programs in youth soccer have implemented motor diagnostics measuring performance factors. However, the predictive value of such tests for adult success is a controversial topic in talent research. This prospective cohort study evaluated the long-term predictive value of 1) motor tests and 2) players' speed abilities (SA) and technical skills (TS) in early adolescence. The sample consisted of 14,178 U12 players from the German talent development program. Five tests (sprint, agility, dribbling, ball control, shooting) were conducted and players' height, weight as well as relative age were assessed at nationwide diagnostics between 2004 and 2006. In the 2014/15 season, the players were then categorized as professional (n = 89), semi-professional (n = 913), or non-professional players (n = 13,176), indicating their adult performance level (APL). The motor tests' prognostic relevance was determined using ANOVAs. Players' future success was predicted by a logistic regression threshold model. This structural equation model comprised a measurement model with the motor tests and two correlated latent factors, SA and TS, with simultaneous consideration for the manifest covariates height, weight and relative age. Each motor predictor and anthropometric characteristic discriminated significantly between the APL (p < .001; η2 ≤ .02). The threshold model significantly predicted the APL (R2 = 24.8%), and in early adolescence the factor TS (p < .001) seems to have a stronger effect on adult performance than SA (p < .05). Both approaches (ANOVA, SEM) verified the diagnostics' predictive validity over a long-term period (≈ 9 years). However, because of the limited effect sizes, the motor tests' prognostic relevance remains ambiguous. A challenge for future research lies in the integration of different (e.g., person-oriented or multilevel) multivariate approaches that expand beyond the "traditional" topic of single tests' predictive validity and toward more theoretically founded issues.


American Football
#1 The Effects of Cardiovascular Fitness and Body Composition on Maximal Core Temperature in Collegiate Football Players During Pre-season
Reference: J Strength Cond Res. 2017 Jul 14. doi: 10.1519/JSC.0000000000002027. [Epub ahead of print]
Authors: McClelland JM, Godek SF, Chlad PS, Feairheller DL, Morrison KE
Summary: This study evaluated the effects of BMI and aerobic fitness (VO2max) on maximal core temperature values (Tcmax) in 17 NCAA Division III football players during pre-season. The subjects included nine backs (BKs) and eight linemen (LM). VO2max testing was performed one week prior to pre-season. Core temperature was monitored via ingestible sensor every 10 min during practices on day 4(D1), day 5(D2), day 7(D3), and post-acclimatization on day 14(D4). Wet bulb globe temperature (WBGT) was recorded on each collection day. Independent, paired t-tests and Pearson's correlations were performed (α=0.05). There were no significant correlations between VO2max and Tcmax on D1 (WBGT=29.07°C) or D2 (WBGT=30.93°C), but on D3 (WBGT=31.39 °C) there was a non-significant moderate negative correlation (r=-0.564, P=0.090). There were no significant correlations between BMI and Tcmax on D1or D2, but on D3 there was a non-significant moderate positive correlation (r=0.596, P=0.069). Paired t-tests revealed that overall Tcmax (D1-3) (38.56±0.32°C) was statistically higher (P=0.002) than D4 (38.16±0.30 °C). Independent t-tests between groups showed the Tcmax values during pre-acclimatization (D1-D3) were significantly higher in LM (38.50±0.37°C) than BKs (38.16±0.35°C) (P=0.007). VO2max was significantly lower (P=0.006) in LM [36.89±6.40 ml/kg•min] than BKs [47.44±7.09 ml/kg•min] and BMI was significantly higher (P=0.019) in LM (35.59±4.00 kg/m) than BKs (28.68±3.38 kg/m). The results of this study demonstrate that LM are significantly less fit than BKs and have a greater BMI. When WBGT was the highest on D3, the results suggest that those with lower VO2max and higher BMI experienced a higher Tcmax.


#2 Temperate-Water Immersion as a Treatment for Hyperthermic Humans Wearing American Football Uniforms
Reference: J Athl Train. 2017 Jul 17. doi: 10.4085/1062-6050-52.5.05. [Epub ahead of print]
Authors: Miller KC, Truxton T, Long B
Summary: Cold-water immersion (CWI; 10°C) can effectively reduce body core temperature even if a hyperthermic human is wearing a full American football uniform (PADS) during treatment. Temperate-water immersion (TWI; 21°C) may be an effective alternative to CWI if resources for the latter (eg, ice) are unavailable. The purpose was to measure rectal temperature (Trec) cooling rates, thermal sensation, and Environmental Symptoms Questionnaire (ESQ) scores of participants wearing PADS or shorts, undergarments, and socks (NOpads) before, during, and after TWI. Thirteen physically active, unacclimatized men (age = 22 ± 2 years, height = 182.3 ± 5.2 cm, mass = 82.5 ± 13.4 kg, body fat = 10% ± 4%, body surface area = 2.04 ± 0.16 m2). Participants exercised in the heat (40°C, 50% relative humidity) on 2 days while wearing PADS until Trec reached 39.5°C. Participants then underwent TWI while wearing either NOpads or PADS until Trec reached 38°C. Thermal sensation and ESQ responses were collected at various times before and after exercise. Temperate-water immersion duration (minutes), Trec cooling rates (°C/min), thermal sensation, and ESQ scores were used as outcome measures. Participants had similar exercise times (NOpads = 38.1 ± 8.1 minutes, PADS = 38.1 ± 8.5 minutes), hypohydration levels (NOpads = 1.1% ± 0.2%, PADS = 1.2% ± 0.2%), and thermal sensation ratings (NOpads = 7.1 ± 0.4, PADS = 7.3 ± 0.4) before TWI. Rectal temperature cooling rates were similar between conditions (NOpads = 0.12°C/min ± 0.05°C/min, PADS = 0.13°C/min ± 0.05°C/min; t12 = 0.82, P = .79). Thermal sensation and ESQ scores were unremarkable between conditions over time. Temperate-water immersion produced acceptable (ie, >0.08°C/min), though not ideal, cooling rates regardless of whether PADS or NOpads were worn. If a football uniform is difficult to remove or the patient is noncompliant, clinicians should begin water-immersion treatment with the athlete fully equipped. Clinicians should strive to use CWI to treat severe hyperthermia, but when CWI is not feasible, TWI should be the next treatment option because its cooling rate was higher than the rates of other common modalities (eg, ice packs, fanning).


#3 Influence of Body Composition on Functional Movement Screen™ Scores in Collegiate Football Players
Reference: J Sport Rehabil. 2017 Jul 17:1-21. doi: 10.1123/jsr.2015-0080. [Epub ahead of print]
Authors: Nicolozakes CP, Schneider DK, Rower B, Borchers J, Hewett TE
Summary: The Functional Movement Screen (FMS™) is used to identify movement asymmetries and deficiencies. While obesity has been reported to impede movement, the correlation between body mass index (BMI), body fat percentage (BF%), and FMS™ in athletes is unknown. The objective was to determine if there is a relationship between BMI, BF%, and FMS™ scores in a sample of National Collegiate Athletic Association (NCAA) Division I football athletes. 38 male freshman football players (18.0 ± 0.7 y, 185.3 ± 5.5 cm, 103.9 ± 20.3 kg) participated in this study.  Height, weight, and BF% were collected, and subjects underwent the FMS™ conducted by a certified athletic trainer. The dependent variables were BMI, BF%, composite FMS™ score, and seven individual FMS™ test scores. Subjects were grouped as normal BMI (BMI < 30 kg/m2) or obese (BMI ≥ 30 kg/m2). A composite FMS™ score of ≤14 and an individual FMS™ score of ≤1 were classified as cut-offs for poor movement performance. A negative correlation between composite FMS™ score and BMI approached significance (p = 0.07, ρ = -0.296). A negative correlation between composite FMS™ score and BF% was significant (p = 0.010, ρ = -0.449). There was a significant difference in the number of obese subjects scoring below the composite FMS™ cut-off (χ2 = 5.179, p = 0.023) and the individual FMS™ cut-off on the deep squat (χ2 = 6.341, p = 0.012), hurdle step (χ2 = 9.870, p = 0.002), and in-line lunge (χ2 = 5.584, p = 0.018) when compared to normal BMI subjects. Increased BF% and BMI relate to lower composite FMS™ and individual FMS™ test scores, indicating potentially poor movement patterns in larger NCAA football athletes. Future research should focus on examining lower extremity-specific FMS™ tasks individually from composite FMS™ scores.

Mon

21

Aug

2017

Latest research in football - week 32 - 2017

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 Conservative Management for Stable High Ankle Injuries in Professional Football Players
Reference: Sports Health. 2017 Jul 1:1941738117720639. doi: 10.1177/1941738117720639. [Epub ahead of print]
Authors: Knapik DM, Trem A, Sheehan J, Salata MJ, Voos JE
Summary: High ankle "syndesmosis" injuries are common in American football players relative to the general population. At the professional level, syndesmotic sprains represent a challenging and unique injury lacking a standardized rehabilitation protocol during conservative management. PubMed, Biosis Preview, SPORTDiscus, PEDro, and EMBASE databases were searched using the terms syndesmotic injuries, American football, conservative management, and rehabilitation. When compared with lateral ankle sprains, syndesmosis injuries result in significantly prolonged recovery times and games lost. For stable syndesmotic injuries, conservative management features a brief period of immobilization and protected weightbearing followed by progressive strengthening exercises and running, and athletes can expect to return to competition in 2 to 6 weeks. Further research investigating the efficacy of dry needling and blood flow restriction therapy is necessary to evaluate the benefit of these techniques in the rehabilitation process. Successful conservative management of stable syndesmotic injuries in professional American football athletes requires a thorough understanding of the anatomy, injury mechanisms, diagnosis, and rehabilitation strategies utilized in elite athletes.


#2 A comprehensive strength testing protocol offers no clinical value in predicting risk of hamstring injury: a prospective cohort study of 413 professional football players
Reference: Br J Sports Med. 2017 Jul 29. pii: bjsports-2017-097754. doi: 10.1136/bjsports-2017-097754. [Epub ahead of print]
Authors: van Dyk N, Bahr R, Burnett AF, Whiteley R, Bakken A, Mosler A, Farooq A, Witvrouw E
Summary: Hamstring injuries remain prevalent across a number of professional sports. In football, the incidence has even increased by 4% per year at the Champions League level over the last decade. The role of muscle strength or strength ratios and their association with risk of hamstring injury remain restricted by small sample sizes and inconclusive results. The purpose of this study is to identify risk factors for hamstring injury in professional football players in an adequately powered, prospective cohort study. Using both established (isokinetic) and novel (eccentric hamstring test device) measures of muscle strength, we aimed to investigate the relationship between these strength characteristics over the entire range of motion with risk of hamstring injury. All teams (n=18) eligible to compete in the premier football league in Qatar underwent a comprehensive strength assessment during their annual periodic health evaluation at Aspetar Orthopaedic and Sports Medicine Hospital in Doha, Qatar. Variables included isokinetic strength, Nordic hamstring exercise strength and dynamic hamstring: quadriceps ratios. Of the 413 players included (68.2% of all league players), 66 suffered a hamstring injury over the two seasons. Only isokinetic quadriceps concentric at 300°/s (adjusted for bodyweight) was associated with risk of hamstring injury when considered categorically. Age, body mass and playing position were also associated with risk of hamstring injury. None of the other 23 strength variables examined were found to be associated with hamstring injury. The clinical value of isolated strength testing is limited, and its use in musculoskeletal screening to predict future hamstring injury is unfounded.


#3 The effects of football match congestion in an international tournament on hip adductor squeeze strength and pain in elite youth players
Reference: J Sports Sci. 2017 Aug 3:1-6. doi: 10.1080/02640414.2017.1363452. [Epub ahead of print]
Authors: Wollin M, Pizzari T, Spagnolo K, Welvaert M, Thorborg K
Summary: The purpose of this study was to investigate the effect of a congested international tournament match schedule on adductor strength and pain in elite youth football players. Twenty-two male players (age: 15.53 ± 0.48 years, height: 174.87 ± 7.59 cm, weight: 67.45 ± 7.40 kg) were included. The 5-second adductor squeeze strength was captured daily using a hand-held dynamometer during a 7-game international tournament. Pain during the squeeze test was recorded using numerical pain ratings (0-10) to quantify groin pain. Sessional rate of perceived exertion (sRPE) was collected during the tournament. Adductor strength changed significantly during the tournament in relation to time (F(14,294.94) = 1.89, p = 0.027) and cumulative sRPE (F(1,314) = 5.59, p = 0.019). Cumulative sRPE displayed a negative relationship with strength (B = -0.008, SE = 0.0032, 95%CI = -0.014,-0.002). The results indicate that for every 100 match sRPE arbitrary units the squeeze peak force reduced by 0.8N. Sixteen (72.7%) players demonstrated clinically meaningful strength reductions (>15%) during the tournament. Match congestion impacts on hip adductor squeeze strength in male youth football players. A negative relationship between match sRPE and adductor strength exists. Player monitoring involving the 5-second adductor squeeze test can be captured effectively and is suitable to include as part of secondary injury prevention during or immediately after a congested tournament.


#4 Response requirements affect offside judgments in football (soccer)
Reference: Psychol Res. 2017 Aug 1. doi: 10.1007/s00426-017-0902-6. [Epub ahead of print]
Authors: Fasold F, Wühr P, Memmert D
Summary: Judging offside in football represents a typical go-nogo task (offside-raising the flag, no offside-no response). Nevertheless, several studies involved two-choice tasks (e.g. offside-press key A, no offside-press key B) to investigate potential sources of errors in offside situations. While go-nogo and choice-response tasks are commonly used in experimental psychology, response preferences may differ between the two tasks. Therefore, we investigated the impact of response requirements on offside judgments in a sample of male participants without experience in professional refereeing. Each participant judged displays of potential offside situations in a go-nogo condition and in a two-choice condition. The results show that response requirements affected the response bias of the participants and suggest that go-nogo requirements increase the preference for the positive response (i.e. the offside response) as compared to the two-choice task. We discuss both methodological and theoretical implications of this finding.


#5 Greenhouse gas emissions as a result of spectators travelling to football in England
Reference: Sci Rep. 2017 Aug 1;7(1):6986. doi: 10.1038/s41598-017-06141-y.
Authors: Dosumu A, Colbeck I, Bragg R
Download link: https://www.nature.com/articles/s41598-017-06141-y.pdf
Summary: Transport remains a critical avenue in the attempt to reduce greenhouse gas (GHG) emissions and any significant effort to reduce travel GHG emissions will need to encourage a movement towards more fuel-efficient, less polluting behaviours. The aim of this paper is to calculate GHG emissions arising from the travel of spectators to and from football games within eight football tiers (3 to 10) in England, and to extrapolate this to a national level. The study comprised of 1649 participants with an average age of 42 years (M = 42.63, SD = 17.10). Participants travelled to and from games by walking, cycling, car, bus, train or taxi. The average distance travelled to and from games was 41.5 km. A Kruskal-Wallis test was conducted to evaluate differences in travel related GHG emissions between the eight football tiers during the 2012/13 season. The results indicate significant differences between football tiers' GHG emissions, H(7) = 46.474, p < 0.001. The annual GHG emission of spectators from the 8 tiers for the 2012/13 season was estimated at 56,237 tonnes of CO2e, accounting for less than 0.05% of transport emissions in England. Football authorities should have robust travel plans and educate spectators to employ more sustainable travel plans to games.


#6 Effects of football sporting activity on renal and liver functions among young undergraduate students of a Nigerian tertiary institution
Reference: BMJ Open Sport Exerc Med. 2017 Jul 11;3(1):e000223. doi: 10.1136/bmjsem-2017-000223. eCollection 2017.
Authors: Ekun OA, Emiabata AF, Abiodun OC, Ogidi NO, Adefolaju FO, Ekun OO
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5530113/pdf/bmjsem-2017-000223.pdf
Summary: Football sporting exercise is one of the most popular events in the world. While there are well-documented reports on the effects of different athletic sporting activities on the biochemical markers of renal and liver functions, there are paucity of well-documented reports on the effects of football activity on Nigerian sportsmen, hence the need for this study. Biochemical markers of renal and liver functions (urea, creatinine, aspartate aminotransaminase (AST), alanine aminotransaminase (ALT), alkaline phosphatase (ALP)) were determined using Cobas c 111 auto-analyser by Roche. The mean urea (mmol/L)±SEM, creatinine (μmol/L)±SEM, AST (U/L)±SEM, ALT (U/L)±SEM and ALP (U/L)±SEM values before and after soccer exercise were 3.56±0.12, 3.76±0.13, p=0.000; 79.36±1.53, 95.90±2.03, p=0.000; 32.54±1.15, 35.81±1.32, p=0.000; 15.68±1.02, 13.97±0.81, p=0.000; and 82.21±3.67, 86.08±3.86, p=0.046, respectively. Pearson's degree of association for AST and ALT before and after exercise were r=0.678, p=0.000 and r=0.770, p=0.000, respectively; ALT and ALP before exercise showed a positive and significant association (r=0.317, p=0.028). On the other hand, there was a negative but insignificant correlation between urea before exercise and ALP after exercise (r=-0.003, p=0.982) and urea before exercise versus AST after exercise (r=-0.120, p=0.418). A positive but insignificant association was observed between urea and creatinine before exercise (r=0.093, p=0.530). Football sporting event is associated with an increase in urea, creatinine, AST and ALP plasma values, and such interpretation of these parameters among sportsmen should be done with caution.


#7 Benign paroxysmal positional vertigo (BPPV) diagnosis and treatment in an elite professional football (soccer) player
Reference: BMJ Case Rep. 2017 Jul 24;2017. pii: bcr-2017-220000. doi: 10.1136/bcr-2017-220000.
Authors: Burrows L, Price R
Summary: A 33-year-old male professional football player suffered from acute-onset dizziness following a lower limb soft tissue treatment in prone lying. Symptoms included spinning vertigo lasting for 30's, headache, visual vertigo and disorientation. Clinical examination of balance and vestibular systems confirmed a left posterior canalithiasis benign paroxysmal positional vertigo (BPPV) and excluded other central and peripheral causes of dizziness. Two cycles of a left Epley manoeuvre were performed. An Epley manoeuvre abolished the BPPV and negated the need for medication. The player was able to return to play without dizziness within 24 hours completely symptom free. BPPV can be successfully identified and treated in elite football players and they can see a return to training and games within 24 hours. There are no epidemiology studies for this group of elite athletes either male or female despite increased occupational risk factors.


#8 Eccentric Training after a Traumatic Apophysis Fracture at the Spina Iliaca Anterior Inferior: Case Study of a Junior Football Player, [Article in German]
Reference: Sportverletz Sportschaden. 2017 Jul 26. doi: 10.1055/s-0043-113209. [Epub ahead of print]
Authors: Landkammer Y, Rieder F, Sassmann R, Herfert J, Wicker A.
Summary: Eccentric training is an established training method in competitive sports. It has been used effectively to improve muscle strength during rehabilitation after cruciate ligament reconstruction. However, it is still uncertain whether or not eccentric training contributes to successful rehabilitation after apophysis fractures. A fourteen-year-old soccer player, forward position, presents with an apophysis avulsion located at the right spina iliaca anterior inferior. After completing an early rehabilitation phase and isokinetic concentric strength development, the patient starts an eccentric training programme eight weeks after the injury, including training on an isokinetic dynamometer (Biodex) for four weeks, followed by a four-week eccentric ergometer training (Eccentron). Before and after each eccentric training phase, isokinetic maximum strength tests of the knee extensors and flexors are performed with angular velocities of 60 degrees per second (°/sec.), 180°/sec. and 240°/sec. In response to the eight-week eccentric rehabilitation program, maximum torque increases in all angular velocities in the injured (60°/sec. + 14.4 %; 180°/sec. + 8.8 %; 240°/sec. + 6.3 %) and the uninjured leg (60°/sec. + 15.6 %; 180°/sec. + 1.9 %; 240°/sec. + 8.1 %) between the first and the last test. Furthermore, neuromuscular coordination has improved during the eccentric training sessions. This case study demonstrates that controlled eccentric training in the open and closed kinetic chain increases coordination and strength of the trained muscles and therefore should be regarded as a valuable contribution toward a safe return to sport after apophysis fractures.


#9 Influence of Match Location, Quality of Opponents, and Match Status on Movement Patterns in Brazilian Professional Football Players
Reference: J Strength Cond Res. 2017 Aug;31(8):2155-2161. doi: 10.1519/JSC.0000000000001674.
Authors: Aquino R, Munhoz Martins GH, Palucci Vieira LH, Menezes RP
Summary: The aim of this study was to examine the independent and interactive effects of match location, quality of opponents, and match status on the movement patterns in a professional Brazilian football team. Sixteen matches of the fourth division Brazilian Championship of 2015 were analyzed during the competitive stages (classifier, 8 matches; octave-finals, 2 matches; quarterfinals, 2 matches; semifinals, 2 matches; and finals, 2 matches). A 5-Hz Global Positioning System Sports QSTARZ was used to record the total distance (TD), maximum speed (VMAX), average speed (VAVERAGE), and frequency of high-intensity activities (HIA). The Student's t-test for independent samples showed significantly higher values (p ≤ 0.05) of VMAX, VAVERAGE, and HIA in home matches when compared with away matches. Comparing the quality of opponents, statistically higher values of TD, VMAX, and HIA were found when the team played against strong opponents. Regarding match status, 1-way analysis of variance demonstrated that when the team won presented significantly higher values of TD, VMAX, VAVERAGE, and HIA compared with matches when the team lost. There were no substantial interactive effects of match situational variables on movement patterns. Finally, multiple linear regression showed that the variable quality of opponents has a higher relative contribution to the variance in HIA (19%) than match status (16%) and match location (4%). In particular, the results indicate that physical performance in professional football is influenced by match situational variables, resulting in a change in the team's style of play.


#10 The Influence of Tactical and Situational Variables on Offensive Sequences during Elite Football Matches
Reference: J Strength Cond Res. 2017 Jul 19. doi: 10.1519/JSC.0000000000002147. [Epub ahead of print]
Authors: Sarmento H, Figueiredo A, Lago-Penas C, Milanovic Z, Barbosa A, Tadeu P, Bradley PS
Summary: This study examined the influence of tactical and situational variables on offensive sequences during elite football matches. A sample of 68 games and 1694 offensive sequences from the Spanish La Liga, Italian Serie A, German Bundesliga, English Premier League and Champions League were analysed using chi-square and logistic regression analyses. Results revealed that counterattacks (OR=1.44; 95% CI: 1.13 to 1.83; P<0.01) and fast attacks (OR=1.43; 95% CI: 1.11 to 1.85; P<0.01) increased the success of an offensive sequence by 40% compared with positional attacks. The chance of an offensive sequence ending effectively in games from the Spanish, Italian and English Leagues were higher than in the Champions League. Offensive sequences that started in the pre-offensive or offensive zones were more successful than those started in the defensive zones. An increase of 1 second in the offensive sequence duration and an extra pass resulted in a decrease of 2% (OR=0.98; 95% CI: 0.98 to 0.99; P<0.001) and 7% (OR=0.93; 95% CI: 0.91 to 0.96; P<0.001), respectively in the probability of its success. These findings could assist coaches in designing specific training situations that improve the effectiveness of the offensive process.


#11 Training and acute exercise modulates mitochondrial dynamics in football players' blood mononuclear cells
Reference: Eur J Appl Physiol. 2017 Jul 26. doi: 10.1007/s00421-017-3684-z. [Epub ahead of print]
Authors: Busquets-Cortes C, Capo X, Martorell M, Tur JA, Sureda A, Pons A
Summary: Regular physical activity induces oxidative stress but also causes adaptations in antioxidant defences including the nuclear factor κB (NF-κB) pathway, which activates target genes related to antioxidant defences such as uncoupling proteins (UCPs), and mitochondrial biogenesis mediated by peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). The aim of the study was to determine the effect of long-term training and acute exercise on oxidant/antioxidant status and the expression of mitochondrial biogenesis genes in peripheral blood mononuclear cells (PBMCs). Twelve professional football players performed an 8-week exercise programme comprising a daily 2-h football training session. Blood samples were taken before and after the training season. The results reported a significant increase in antioxidant protein levels and in mitochondrial proteins in resting conditions after the 8-week training period. PGC1α, UCP-2 and mitofusin 2 protein levels also increased after acute exercise compared to pre-exercise levels. After the training, the expression of PGC1α, cytochrome c oxidase subunit IV and mitochondrial NADH dehydrogenase subunit 5 messenger RNA (mRNA) significantly augmented after the acute physical activity compared to pre-exercise levels; while no changes occurred in these mRNA in basal conditions. NF-κB activation and ROS production reported a significant increase after acute exercise. Training increases the levels of proteins related to mitochondrial biogenesis and improves the antioxidant capabilities of mitochondria in PBMCs among well-trained football players. Acute exercise may act as an inducer of mitochondrial biogenesis through NF-κB activation and PGC1α gene expression.


#12 Injuries Among Recreational Football Players: Results of a Prospective Cohort Study
Reference: Clin J Sport Med. 2017 Jul 14. doi: 10.1097/JSM.0000000000000425. [Epub ahead of print]
Authors: Donmez G, Korkusuz F, Ozcakar L, Karanfil Y, Dursun E, Kudaş S, Doral MN.
Summary: The purpose was to establish the incidence and patterns of football injuries and associated consequences in daily life and labor loss, among public employees. A total of 1821 recreational players from 78 teams participated in this study. Injury rates (injuries per 1000 hours of football exposure) during tournament by age group, as well as prevalence, severity, and injury types were recorded. The data regarding the occurrence (eg, location, type, circumstances) and consequences (eg, absenteeism, medical treatment, labor loss) of injuries were collected. Of the 1821 football players registered for participation, 57% (n = 1038) were included in the study with the returned questionnaire forms. In total, 257 matches were played with a total exposure time of 5654 hours. A total of 218 injuries were recorded in 192 players (10.5%), resulting in a mean of 0.85 time-loss injuries per match (38.6 per 1000 hours). Severe injuries constituted 42.6% of all injuries, and 28.9% of all injuries caused the participants to be absent at least 1 day for the next working day. The total labor loss was 1196 days for all injuries. The rate of missing subsequent working day was significantly less for muscle injuries (P < 0.05). The risk of injury in recreational football players is relatively high causing significant labor loss. The results suggest that prevention programs should consider specific injury characteristics, as there is a greater incidence of muscle and anterior cruciate ligament injuries in this population.



American Football
#1 Performance and Return to Sport After Achilles Tendon Repair in National Football League Players
Reference: Foot Ankle Int. 2017 Jul 1:1071100717718131. doi: 10.1177/1071100717718131. [Epub ahead of print]
Authors: Jack RA 2nd, Sochacki KR, Gardner SS, McCulloch PC, Lintner DM, Cosculluela PE, Varner KE, Harris JD
Summary: Achilles tendon injuries are common in sports, including football. The purpose of this study was to determine (1) return-to-sport rate in National Football League (NFL) players following Achilles tendon repair, (2) postoperative career length and games per season, (3) pre- and postoperative performance, and (4) postoperative performance compared with control players matched by position, age, years of experience, and performance. Publicly available records were used to identify NFL players who underwent Achilles tendon repair and matched controls were identified. Ninety-five players (98 surgeries) were analyzed (mean age 28.2 ± 2.8 years; mean 5.5 ± 2 .8 years in NFL at time of surgery). Demographic and performance data were collected. Comparisons between case and control groups and preoperative and postoperative time points were made using paired-samples Student t tests. Seventy-one (72.4%) players were able to return to sport in the NFL at a mean of 339.8 ± 84.8 days following surgery. Thirty-one (32%) Achilles tendon repairs were performed during training camp or preseason. Controls (3.6 ± 2.1 years) had a significantly longer NFL career ( P < .05) than players who underwent Achilles tendon repair (2.7 ± 2.1 years). There was no significant difference in games per season in subsequent seasons following surgery compared with controls. Postoperative performance scores were significantly worse ( P < .05) for running backs (RBs) (n = 4) and linebackers (LBs) (n = 12) compared to preoperative scores. LBs had significantly worse postoperative performance scores when compared to matched controls ( P < .05). Following Achilles tendon repair, less than 75% of players returned to the NFL. Postoperative career length was 1 season shorter than matched controls. No difference was observed in the number of games per season played compared to matched controls. Postoperative performance scores were significantly worse for RBs and LBs compared to preoperative and LBs had significantly worse postoperative performance when compared to matched controls.


#2 Clinicopathological Evaluation of Chronic Traumatic Encephalopathy in Players of American Football
Reference: JAMA. 2017 Jul 25;318(4):360-370. doi: 10.1001/jama.2017.8334.
Authors: Mez J, Daneshvar DH, Kiernan PT, Abdolmohammadi B, Alvarez VE, Huber BR, Alosco ML, Solomon TM, Nowinski CJ, McHale L, Cormier KA, Kubilus CA, Martin BM, Murphy L, Baugh CM, Montenigro PH, Chaisson CE, Tripodis Y, Kowall NW, Weuve J, McClean MD, Cantu RC, Goldstein LE, Katz DI, Stern RA, Stein TD, McKee AC
Summary: Players of American football may be at increased risk of long-term neurological conditions, particularly chronic traumatic encephalopathy (CTE). The purpose was to determine the neuropathological and clinical features of deceased football players with CTE. Case series of 202 football players whose brains were donated for research. Neuropathological evaluations and retrospective telephone clinical assessments (including head trauma history) with informants were performed blinded. Online questionnaires ascertained athletic and military history. Participation in American football at any level of play. Neuropathological diagnoses of neurodegenerative diseases, including CTE, based on defined diagnostic criteria; CTE neuropathological severity (stages I to IV or dichotomized into mild [stages I and II] and severe [stages III and IV]); informant-reported athletic history and, for players who died in 2014 or later, clinical presentation, including behavior, mood, and cognitive symptoms and dementia. Among 202 deceased former football players (median age at death, 66 years [interquartile range, 47-76 years]), CTE was neuropathologically diagnosed in 177 players (87%; median age at death, 67 years [interquartile range, 52-77 years]; mean years of football participation, 15.1 [SD, 5.2]), including 0 of 2 pre-high school, 3 of 14 high school (21%), 48 of 53 college (91%), 9 of 14 semiprofessional (64%), 7 of 8 Canadian Football League (88%), and 110 of 111 National Football League (99%) players. Neuropathological severity of CTE was distributed across the highest level of play, with all 3 former high school players having mild pathology and the majority of former college (27 [56%]), semiprofessional (5 [56%]), and professional (101 [86%]) players having severe pathology. Among 27 participants with mild CTE pathology, 26 (96%) had behavioral or mood symptoms or both, 23 (85%) had cognitive symptoms, and 9 (33%) had signs of dementia. Among 84 participants with severe CTE pathology, 75 (89%) had behavioral or mood symptoms or both, 80 (95%) had cognitive symptoms, and 71 (85%) had signs of dementia. In a convenience sample of deceased football players who donated their brains for research, a high proportion had neuropathological evidence of CTE, suggesting that CTE may be related to prior participation in football.


#3 The Influence of Heavier Football Helmet Faceguards on Head Impact Location and Severity
Reference: Clin J Sport Med. 2017 Jul 21. doi: 10.1097/JSM.0000000000000437. [Epub ahead of print]
Authors: Schmidt JD, Phan TT, Courson RW, Reifsteck F 3rd, Merritt ED, Brown CN.
Summary: The purpose was to determine whether players with heavier faceguards have increased odds of sustaining top of the head impacts and head impacts of higher severity. Thirty-five division I collegiate football players participated in this study. Faceguard mass was measured. Head impact location and severity (linear acceleration [gravity], rotational acceleration [radian per square second], and Head Impact Technology severity profile [unitless]) were captured for 19 379 total head impacts at practices using the Head Impact Telemetry System. Players' faceguards were categorized as either heavier (>480 g) or lighter (≤480 g) using a median split. Odds ratios (ORs) and 95% confidence intervals (CIs) were computed for sustaining top of the head impacts between faceguard groups using a random intercepts generalized logit model. We compared head impact severity between groups using random intercepts general linear models (α = 0.05). Player position was included in all models. Overall, the 4 head impact locations were equally distributed across faceguard groups (F(3,26) = 2.16, P = 0.117). Football players with heavier faceguards sustained a higher proportion impacts to the top of the head (24.7% vs 17.5%) and had slightly increased odds of sustaining top (OR, 1.72; 95% CI, 1.01-2.94) head impacts rather than front of the head impacts. Football players wearing heavier faceguards might be slightly more prone to sustaining a higher proportion of top of the head impacts, suggesting that greater faceguard mass may make players more likely to lower their head before collision. Individuals involved with equipment selection should consider the potential influence of faceguard design on head impact biomechanics when recommending the use of a heavier faceguard.


#4 Large case series documents chronic brain damage in players of American football
Reference: BMJ. 2017 Jul 25;358:j3602. doi: 10.1136/bmj.j3602.
Author: McCarthy M

#5 The Role of Neck Muscle Activities on the Risk of Mild Traumatic Brain Injury in American Football
Reference: J Biomech Eng. 2017 Jul 28. doi: 10.1115/1.4037399. [Epub ahead of print]
Authors: Jin X, Feng Z, Mika VH, Li H, Viano D, Yang KH
Summary: Concussion, or mild TBI (mTBI), is frequently associated with sports activities. It has generally been accepted that neck strengthening exercises are effective as a preventive strategy for reducing sports-related concussion risks. However, the interpretation of the link between neck strength and concussion risks remains unclear. In this study, a typical helmeted head-to-head impact in American football was simulated using the head and neck complex finite element model. The impact scenario selected was previously reported in lab-controlled incident reconstructions from high-speed NFL video footages using two head-neck complexes taken from Hybrid III dummies. Four different muscle activation strategies were designed to represent no muscle response, a reactive muscle response, a pre-activation response, and response due to stronger muscle strength. Head kinematics and various head/brain injury risk predictors were selected as response variables to compare the effects of neck muscles on the risk of sustaining the concussion. Simulation results indicated that active responses of neck muscles could effectively reduce the risk of brain injury. Also, anticipatory muscle activation played a dominant role on impact outcomes. Increased neck strength can decrease the time to compress the neck and its effects on reducing brain injury risks need to be further studied.


#7 Sport-related structural brain injury: Three cases of subdural hemorrhage in American high school football
Reference: World Neurosurg. 2017 Jul 20. pii: S1878-8750(17)31172-5. doi: 10.1016/j.wneu.2017.07.072. [Epub ahead of print]
Authors: Yengo-Kahn AM, Gardner RM, Kuhn AW, Solomon GS, Bonfield CM, Zuckerman SL
Summary: The risk of sport-related concussion (SRC) has emerged as a major public health concern. In rare instances, sport-related head injuries can be even more severe, such as subdural hemorrhage, epidural hemorrhage, or malignant cerebral edema. Unlike SRCs, sport-related structural brain injury (SRSBI) is rare, may require neurosurgical intervention, and can lead to permanent neurologic deficit or death. Data characterizing SRSBI is limited and many have recognized the need to better understand these catastrophic brain injuries. The goal of the current series is to describe, in detail, the presentation, management and outcomes of examples of these rare injuries. During the Fall of 2015, three high school football players presented with acute subdural hemorrhages (SDH) following in-game collisions and were treated at our institution within a span of 2 months. For the two athletes who required surgical intervention, a previous SRC was sustained within four weeks prior to the catastrophic event. One year after injury, two players have returned to school, though with persistent deficits. One patient remains non-verbal and wheelchair-bound. None of the athletes has returned to sports. Acute SDH resultant from an in-game football collision is rare. The temporal proximity of the reported SRSBIs to recent SRCs emphasizes the importance of return to play protocols and raises questions regarding the possibility of second impact syndrome. Although epidemiologic conclusions cannot be drawn from this small sample, these cases provide a unique opportunity to demonstrate the presentation, management, and long-term outcomes of SRSBI in American high school football.


#9 Global Positioning System Analysis of a High School Football Scrimmage
Reference: J Strength Cond Res. 2017 Aug;31(8):2183-2188. doi: 10.1519/JSC.0000000000001691.
Authors: Gleason BH, Sams ML, Salley JT, Pustina AA, Stone MH
Summary:  The purpose of this study was to examine the physical demands of a high school American football scrimmage. Male high school football players (N = 25) participated in a spring scrimmage. Global positioning system data and game film were recorded throughout the entirety of the scrimmage to determine the total distance covered, the distance covered in different velocity bands, the number of accelerations and decelerations performed, and the work-to-rest ratio of the scrimmage. The athletes were divided into 2 groups: linemen (L) (N = 7) vs. nonlinemen (NL) (N = 8) for statistical analysis, and independent T-tests with Holm's sequential Bonferroni adjustment were used to determine differences in movement characteristics between the L and NL groups. Average play duration was 5.7 ± 2.1 seconds, whereas the rest interval was 33.4 ± 13.6 seconds between plays, for an overall exercise-to-rest ratio of 1:5.9. Total distance, standing and walking distance, running distance, striding distance, sprinting distance, and total high-speed running distance covered by NL was greater than L (statistically significant at p ≤ 0.05). Distances traveled in each velocity band by position and by play are also included to provide context of our findings. Data from the present study add to the pool of support for the use of position-specific training in preparing high school football players for competition.


#10 No Seasonal Changes in Cognitive Functioning Among High School Football Athletes: Implementation of a Novel Electrophysiological Measure and Standard Clinical Measures
Reference: Clin J Sport Med. 2017 Jul 14. doi: 10.1097/JSM.0000000000000420. [Epub ahead of print]
Authors: Broglio SP, Williams R, Rettmann A, Moore B, Eckner JT, Meehan S.
Summary: The purpose was to evaluate neuroelectric and cognitive function relative to a season of football participation. Cognitive and neuroelectric function declines are hypothesized to be present in football athletes. Seventy-seven high school athletes (15.9 + 0.9 years, 178.6 + 7.2 cm, 74.4 + 14.7 kg, and 0.8 + 0.8 self-reported concussions) participating in football (n = 46) and noncontact sports (n = 31). All athletes completed preseason, midseason, and postseason assessments of cognitive and neuroelectric function, self-reported symptoms, and quality of life. All athletes participated in their respective sports without intervention, while head impact exposure in football athletes was tracked using the Head Impact Telemetry System. Cognitive performance was based on Cogstate computerized cognitive assessment tool processing speed, attention, learning, working memory speed, and working memory accuracy scores. ElMindA brain network activation amplitude, synchronization, timing and connectivity brain network activation scores demarcated neuroelectric performance. Quality of life was assessed on the Health Behavior Inventory and Satisfaction with Life Scale and symptoms on the SCAT3 inventory. Football and control sport athletes did not show declines in cognitive or neuroelectric function, quality-of-life measures, or symptom reports across a season of sport participation. These findings refute the notion that routine football participation places athletes at risk for acute cognitive declines. The lack of impairment may be associated with no association with head impacts and cognitive function, increased physical activity offsetting any declines, and/or test sensitivity. How these findings are associated with long-term cognitive function is unknown.

Tue

08

Aug

2017

Latest research in football - week 31 - 2017

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 A Comparison of GPS Workload Demands in Match Play and Small-Sided Games by the Positional Role in Youth Soccer
Reference: J Hum Kinet. 2017 Jun 22;57:129-137. doi: 10.1515/hukin-2017-0054. eCollection 2017 Jun.
Authors: Beenham M, Barron DJ, Fry J, Hurst HH, Figueirdo A, Atkins S
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5504585/pdf/hukin-57-129.pdf
Summary: The external demands of small-sided games (SSGs) according to the positional role are currently unknown. Using a Catapult Minimax X3 5 Hz GPS, with a 100 Hz tri-axial accelerometer, we compared the accumulated tri-axial player workload per min (PLacc·min-1) during friendly youth match play (MP) (11 vs. 11) and SSGs (2 vs. 2, 3 vs. 3, and 4 vs. 4). Significant differences existed between all SSGs and MP for PLacc·min-1 (F = 21.91, p < 0.001, η2 = 0.38), and individual X (F = 27.40, p < 0.001, η2 = 0.43), Y (F = 14.50, p < 0.001, η2 = 0.29) and Z (F = 19.28, p < 0.001, η2 = 0.35) axis loads. Across all conditions, mean PLacc·min-1 was greater for midfielders (p = 0.004, CI: 0.68, 4.56) and forwards (p = 0.037, CI: 0.08, 3.97) than central defenders. In all conditions, greater Y axis values existed for wide defenders (p = 0.024, CI: 0.67, 1.38), midfielders (p = 0.006, CI: 0.18, 1.50) and forwards (p = 0.007, CI: 0.17, 0.15) compared to central defenders. Midfielders reported greater Z axis values compared to central defenders (p = 0.002, CI: 0.40, 2.23). We concluded that SSGs elicited greater external loads than MP, and previous studies may have underestimated the demands of SSGs.


#2 Small-Sided Games in Elite Soccer: Does One Size Fits All?
Reference: Int J Sports Physiol Perform. 2017 Jul 17:1-24. doi: 10.1123/ijspp.2017-0214. [Epub ahead of print]
Authors: Lacome M, Simpson BM, Cholley Y, Lambert P, Buchheit M
Summary: The purpose was to compare the peak intensity of typical Small Sided Games (SSGs) with those of official matches in terms of running demands and mechanical work over different rolling average durations and playing positions. Data were collected in 21 players (25±5 y, 181±7 cm, 77±7 kg) belonging to an elite French football team. SSG data were collected over two seasons during typical training sessions (249 files, 12±4 per player) and official matches (n=12). Players' locomotor activity was recorded using 15-Hz GPS. Total distance (TD, m), high-speed distance (HS, distance above 14.4 km.h-1, m) and mechanical work (MechW, a.u) were analysed during different rolling average periods (1 to 15 min). The SSGs examined were 4v4+Goal Keepers (GKs), 6v6+GKs, 8v8+GKs and 10v10+GKs. Peak TD and HS during 4v4, 6v6 and 8v8 were likely-to-most likely largely lower than during matches (ES: -0.59,±0.38 to -7.36,±1.20). MechW during 4v4 was likely-to-most likely higher than during matches (1-4-min; 0.61±,0.77 to 2.30±,0.64). Relative to their match demands, central defenders (CD) performed more HS than other positions (0.63±,0.81 to 1.61±,0.52) during 6v6. Similarly, central midfielders (CM) performed less MechW than the other positions during 6v6 (0.68,±0.72 to 1.34,±0.99) and 8v8 (0.73,±0.50 to 1.39,±0.32). Peak locomotor intensity can be modulated during SSGs of various formats and durations to either over- or underload match demands, with 4v4 placing the greatest and the least emphasis on MechW and HS, respectively. Additionally, CD and CM tend to be the most and least overloaded during SSGs, respectively.


#3 Importance of physical qualities for speed and change of direction ability in elite female soccer players
Reference: J Strength Cond Res. 2017 Jul 17. doi: 10.1519/JSC.0000000000002114. [Epub ahead of print]
Authors: Emmonds S, Nicholson G, Beggs C, Jones B, Bissas A
Summary: The purpose of this study was to determine the importance of physical qualities for speed and change of direction (CoD) ability in female soccer players. Data were collected on 10 female soccer players who were part of a professional English Women's Super League team. Player assessments included anthropometric (stature and body mass), body composition (dual-energy X-ray absorptiometry), speed (10m, 30m sprint), CoD ability (505 agility), aerobic (Yo-Yo Intermittent Recovery Test), lower-body strength (bilateral knee extensions) and power (countermovement jump [CMJ], squat jump [SJ], 30cm drop jump [DJ]) measures. The relationships between the variables were evaluated using eigenvector analysis and Pearson correlation analysis. Multiple linear regression revealed that the performance variables (10 and 20m speed, mean 505, and CoD deficit mean) can be predicted with almost 100% accuracy (i.e. adjusted R > 0.999) using various combinations of the predictor variables (DJ height, CMJ height, SJ height, lean body mass). An increase of one standard deviation (SD) in DJ height was associated with reductions of -5.636 and -9.082 SD in 10 m and 20 m sprint times. A one SD increase in CMJ also results in a reduction of -3.317 and -0.922 SD respectively in mean 505 and CoD deficit mean values. This study provides comparative data for professional English female soccer players that can be used by strength and conditioning coaches when monitoring player development and assessing the effectiveness of training programmes. Findings highlight the importance of developing reactive strength to improve speed and CoD ability in female soccer players.


#4 Effect of insulin therapy and dietary adjustments on safety and performance during simulated soccer tests in people with type 1 diabetes: study protocol for a randomized controlled trial
Reference: Trials. 2017 Jul 20;18(1):338. doi: 10.1186/s13063-017-2078-1.
Authors: Calvo-Marin J, Torrealba-Acosta G, Campbell M, Gaboury J, Ali A, Chen-Ku CH
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5520333/pdf/13063_2017_Article_2078.pdf
Summary: Despite the reduction in glycemic derangement in patients with type 1 diabetes mellitus (T1D) through dietary and therapeutic adjustments implemented before, during and after continuous exercise, evidence for its effectiveness with intermittent forms of exercise, such as soccer, is still lacking. We designed a study protocol for a randomized, crossover, double-blinded, controlled trial, for the evaluation of the effect that a strategy of dietary and therapeutic modifications may have on safety and performance of persons with T1D in soccer training sessions and cognitive testing. Inclusion criteria comprise: age older than 18 years, more than 2 years since T1D diagnosis, low C-peptide level, a stable insulin regimen, HbA1c less than 9.0% and regular participation in soccer activities. Our primary outcome evaluates safety regarding hypoglycemia events in patients using dietary and therapeutic adjustments, compared with the performance under the implementation of current American Diabetes Association (ADA) usual recommendations for nutritional and pharmacological adjustments for exercise. Additionally, we will evaluate as secondary outcomes: soccer performance, indexed by performance in well-established soccer skill tests, cognitive functions (indexed by Stroop, digital vigilance test (DVT), Corsi block-tapping task (CBP), and rapid visual information processing (RVIP) tests), and glycemic control measured with a continuous glucose monitor (CGM). Dietary and insulin adjustments standardized under a 4-step method strategy have never been tested in a clinical trial setting with intermittent forms of exercise, such as soccer. We hypothesize that through this strategy we will observe better performance by persons with T1D in soccer and cognitive evaluations, and more stable control of glycemic parameters before, during and after exercise execution, indexed by CGM measurements.


#5 Nonoperative Management and Rehabilitation of Osteitis Pubis/Pubic Bone Stress in Professional Soccer Players: A Report of 5 Cases
Reference: J Orthop Sports Phys Ther. 2017 Aug 3:1-20. doi: 10.2519/jospt.2017.7314. [Epub ahead of print]
Authors: McAleer SS, Lippie E, Norman D, Riepenhof H
Summary: Background Pubic bone stress (PBS) is a common acute or chronic response of the pelvis in sports where sprinting, kicking, twisting and cutting are the dominant movements. Little literature exists regarding non-operative rehabilitation strategies for the condition and the outcome of conservative treatment has not been documented. Case Description Five professional and aspiring professional soccer players complaining of pubic symphysis pain, confirmed as PBS on magnetic resonance imaging and objective assessment. All cases followed a non-operative rehabilitation program, featuring functional and clinical objective markers as progression criteria. Acute interventions included pharmacological and physical therapeutic modalities to reduce pain initially. Rehabilitation management focused on improving range of motion ant the hips and thorax, adductor strengthening, trunk and lumbopelvic stability, gym-based strength training and field-based rehabilitation and conditioning. Clinical follow-up was performed at least 8 months following return to play. Outcomes All players demonstrated reduced or resolved pain, increased adductor squeeze strength, and return to pain free training and match-play. Return to training time averaged 40.6 days (range, 30-60) and return to play averaged 49.4 days (range, 38-72) within the 5 players. At final follow up (mean = 29.6 months, range, 16-33) there had been no recurrences. Discussion This case series suggests a non-operative pathway, using clinical and functional progression criteria is a successful protocol in rehabilitating athletes with PBS in returning to sport within 11 weeks.


#6 Activity profiles in U17, U20 and senior women's Brazilian National soccer teams during international competitions: Are there meaningful differences?
Reference: J Strength Cond Res. 2017 Jul 31. doi: 10.1519/JSC.0000000000002170. [Epub ahead of print]
Authors: Ramos GP, Nakamura FY, Penna EM, Wilke CF, Pereira LA, Loturco I, Capelli L, Mahseredjian F, Silami-Garcia E, Coimbra CC.
Summary: The aim of this study was to compare locomotor activity profiles of Brazilian top-class female soccer players competing at distinct age brackets (U17, U20, and Senior). External match load of 14 U17, 14 U20, and 17 Senior female soccer players competing in 6-7 full official international matches were assessed using global positioning systems (GPS). Total distance covered, distance covered in high intensity (HID:15.6-20 kmh), distance covered in sprints (sprint:>20 kmh), number of accelerations (Acc)>1 ms, decelerations (Dec) >-1 ms, and Player Load generally increased across the age brackets (U17<U20<Senior). For all playing positions, Senior athletes presented greater total distance, accelerations, and decelerations than U20 players. For high-intensity distance and sprints, only central defender and midfielder senior players presented greater values than U20 players. Senior players demonstrated higher values in all locomotor activities in comparison to U17 players, irrespective of playing positions. Except for central defenders that presented similar total distance, sprint distance, and number of accelerations between U20 and U17, the majority of match external loads evaluated in all playing positions were greater in U20 than in U17 players. These results provide useful information for player development and should be used to establish appropriate match-specific conditioning drills according to age categories.


#7 Response requirements affect offside judgments in football (soccer)
Reference: Psychol Res. 2017 Aug 1. doi: 10.1007/s00426-017-0902-6. [Epub ahead of print]
Authors: Fasold F, Wuhr P, Memmert D
Summary: Judging offside in football represents a typical go-nogo task (offside-raising the flag, no offside-no response). Nevertheless, several studies involved two-choice tasks (e.g. offside-press key A, no offside-press key B) to investigate potential sources of errors in offside situations. While go-nogo and choice-response tasks are commonly used in experimental psychology, response preferences may differ between the two tasks. Therefore, we investigated the impact of response requirements on offside judgments in a sample of male participants without experience in professional refereeing. Each participant judged displays of potential offside situations in a go-nogo condition and in a two-choice condition. The results show that response requirements affected the response bias of the participants and suggest that go-nogo requirements increase the preference for the positive response (i.e. the offside response) as compared to the two-choice task. We discuss both methodological and theoretical implications of this finding.


#8 Static stretching does not enhance recovery in elite youth soccer players
Reference: BMJ Open Sport Exerc Med. 2017 Apr 22;3(1):e000202. doi: 10.1136/bmjsem-2016-000202. eCollection 2017.
Authors: Pooley S, Spendiff O, Allen M, Moir HJ
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5530097/pdf/bmjsem-2016-000202.pdf
Summary: Static stretching (SS) is a recovery intervention used for the reduction of muscle soreness postexercise. The effects of SS on elite young footballers have received little attention, and therefore the aim of this study was to assess the effects of SS on muscle recovery following competitive soccer matches in elite young footballers. Ten male participants (16±1 years) were recruited from an English Premier League professional soccer academy. Using a controlled crossover design, participants followed one of two recovery interventions (SS or passive recovery (PR)) immediately following completion of competitive soccer matches. Muscle oedema, creatine kinase (CK), countermovement jump with arms (CMJA) performance and perceived muscle soreness were assessed before, immediately after and 48 hours postmatch. Competitive soccer matches significantly induced muscle damage, with time intervals of perceived soreness and CK showing significant increases (p<0.05), and CMJA showing significant decreases between prematch, postmatch and 48 hours postmatch for both SS and PR (p<0.05). Comparisons of the absolute effects of SS with PR only revealed significant decreases for CK 48 hours postmatch (p<0.05) as a result of SS intervention. The current study demonstrated competitive soccer matches induced muscle damage, which may have detrimental effects on future performance within 24-48 hours postmatch. Furthermore, there was limited evidence to suggest SS would assist in the reduction of muscle soreness postexercise. Therefore, it can be argued that SS is not a beneficial recovery option for elite youth soccer players.


#9 Maturity status influences the relative age effect in national top level youth alpine ski racing and soccer
Reference: PLoS One. 2017 Jul 31;12(7):e0181810. doi: 10.1371/journal.pone.0181810. eCollection 2017.
Authors: Muller L, Gonaus C, Perner C, Muller E, Raschner C
Download link: http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0181810&type=printable
Summary: Since the relative age effect (RAE) characterizes a problem in all age categories of alpine ski racing and soccer and the fact that, yet, to date the underlying factors have not been well investigated, the aim of the present study was to assess the influence of the biological maturity status on the RAE among youth alpine ski racers (YSR) and soccer players (SP). In total, 183 male and female YSR selected for national final races and 423 male SP selected for Elite Youth Development Centres were investigated. Additionally, a comparison group of 413 non-athletes was evaluated. The birth months were split into four relative age quarters. The biological maturity status was assessed by the age at peak height velocity (APHV) method; according to the M±SD of the comparison group, the athletes were divided into normal, early and late maturing. Chi2-tests indicated a significant RAE among YSR (χ2(3,N = 183) = 18.0; p<0.001; ω = 0.31) and SP (χ2(3,N = 423) = 33.1; p<0.001; ω = 0.28). In total, only a small number of late maturing athletes were present (0.5-2.3%). Among relatively younger athletes, high percentages of early maturing athletes were found (43.1-43.3%). The findings indicate that relatively younger and less mature athletes are marginalized or totally excluded in alpine ski racing and soccer. Thus, selection criteria in both sports are effectively based on early biological development and relatively older age, both of which should be considered in future in the talent selection process. In this context, the easy feasible method of assessing the APHV can be used.


#10 The isokinetic strength profile of elite soccer players according to playing position
Reference: PLoS One. 2017 Jul 31;12(7):e0182177. doi: 10.1371/journal.pone.0182177. eCollection 2017.
Authors: Sliwowski R, Grygorowicz M, Hojszyk R, Jadczak L
Download link: http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0182177&type=printable
Summary: The aim of this study was to compare isokinetic strength performance profiles in elite soccer players across different field positions. A total of 111 elite international players of Polish Ekstraklasa (the top division in Poland) were examined during the 2010-2015 seasons. The players were classified into six positional roles: central defenders (CD), external defenders (ED), central midfielders (CM), external midfielders (EM), forwards (F), and goalkeepers (G). The concentric isokinetic strength (peak torque [PT] of quadriceps and hamstrings, H/Q ratios) was calculated for the dominant leg and the non-dominant leg at angular velocity of 1.05 rad ·s-1, whereas to assess isokinetic muscle endurance, the total work [TW] at angular velocity of 4.19 rad ·s-1, was taken into consideration. The results showed that isokinetic strength performance varies significantly among players in different playing positions. The analysis of PT for quadriceps (PT-Q) and hamstrings (PT-H) generally showed that the goalkeepers and central midfielders had lower strength levels compared to other playing positions. In the case of PT-H and hamstring/quadricep (H/Q) peak torque ratios, statistically significant differences were also noted for the legs, where mean values noted for the dominant leg were higher than for the non-dominant leg. For TW for quadriceps (TW-Q) and hamstrings (TW-H), statistically significant differences were noted only between playing positions. TW-Q values for goalkeepers were lower than for central defenders and external midfielders. TW-H values for goalkeepers were lower than for central midfielders, central defenders and external midfielders. This study showed that specific functional activity of players in individual positions on the field influences the varied profile of isokinetic strength performance.


#11 Reliability characteristics and applicability of a repeated sprint ability test in male young soccer players
Reference: J Strength Cond Res. 2017 Jul 28. doi: 10.1519/JSC.0000000000002031. [Epub ahead of print]
Authors: Castagna C, Francini L, Krustrup P, Fenarnandes-da-Silva J, Povoas SCA, Bernardini A, D'Ottavio S.
Summary: The aim of this study was to examine the usefulness and reliability characteristics of a repeated sprint ability test considering 5 line sprints of 30-m interspersed with 30-s of active recovery in non-elite outfield young male soccer players. Twenty-six (age 14.9±1.2 years, height 1.72±0.12 cm, body mass 62.2±5.1 kg) players were tested 48 hours and 7 days apart for 5x30-m performance over 5 trials (T1-T5). Short- (T1-T2) and long-term reliability (T1-T3-T4-T5) were assessed with Intraclass Correlation Coefficient (ICC) and with typical error for measurement (TEM). Short- and long-term reliability ICCs and TEMs for total sprint time and best sprint performance were nearly perfect and satisfactory, respectively. Usefulness (as smallest worthwhile change and TEM ratio) resulted acceptable (i.e =1) and good (i.e >1) for total sprint time and best sprint performance, respectively. The present study revealed that the 5x30-m sprint test is a reliable field test in the short and long-term when the sum of sprint times and the best sprint performance are considered as outcome variables. Sprint performance decrements variables showed large variability across trials.


#12 MRI detection of soleus muscle injuries in professional football players
Reference: Skeletal Radiol. 2017 Aug 2. doi: 10.1007/s00256-017-2729-z. [Epub ahead of print]
Authors: Pezzotta G, Querques G, Pecorelli A, Nani R, Sironi S
Summary: The purpose was to describe magnetic resonance imaging (MRI) characteristics of soleus muscle injuries in symptomatic professional football players stratified according to both the Munich consensus statement and the British Athletics Muscle Injury Classification (BAMIC), and to investigate the association between specific MRI features and the "return to play" (RTP). Professional football players with an episode of acute posterior calf pain and impaired function, subsequent to sports activity, underwent ultrasound followed by MRI examination reviewed by two different radiologists with more than 10 years of experience in the musculoskeletal system. MRI features and RTP outcome were evaluated for all types of injuries. During a 36-month period, a total of 20 professional football players were evaluated. According to the Munich consensus, 11 were type 3A, 8 were type 3B, and 1 was type 4, whereas according to the BAMIC, 11 lesions were considered grade 1, 4 grade 2, 4 grade 3, and 1 grade 4. RTP data were available for all patients (mean 3.3 ± 1.6 weeks). Both the Munich consensus and the BAMIC correlated with RTP (Spearman correlation = 0.982 and p < 0.0001 and 0.886 and p < 0.0001 respectively). Extension of edema was an independent prognostic factor for RTP in two different models of multivariate regression analysis (p = 0.044 model A; p = 0.031 model B). The Munich consensus and BAMIC grading systems are useful tools for defining the patient's prognosis and proper rehabilitation time after injury. The MRI feature that we should carefully look for is the extension of edema, as it seems to significantly affect the RTP.


#13 Possession Zone as a Performance Indicator in Football. The Game of the Best Teams
Reference: Front Psychol. 2017 Jul 14;8:1176. doi: 10.3389/fpsyg.2017.01176. eCollection 2017.
Authors: Casal CA, Maneiro R, Arda T, Mari FJ, Losada JL
Summary: Possession time in football has been widely discussed in research but few studies have analyzed the importance of the field area in which possession occurs. The objective of this study was to identify the existence of significant differences in the field zone of ball possession between successful and unsuccessful teams and to acknowledge if the match status modulates the possession model. To this end, 2,284 attacks were analyzed corresponding to the matches in the final phase of the UEFA Euro 2016 France, recording possession time and field zone in which possession occurred. Video recordings of matches were analyzed and coded post-event using notational analysis. We have found that successful offensive game patterns are different from unsuccessful ones. Specifically, field zone in which major possession occurs changes significantly between successful and unsuccessful teams (x2 = 15.72, p < 0.05) and through Welch's T significant differences were detected in possession time between successful and unsuccessful teams (H = 24.289, p < 0.001). The former are characterized by longer possession times, preferably in the middle offensive zone, on the other hand, unsuccessful teams have shorter possession times and preferably on the middle defensive zone. Logistic regression also allowed us to identify that greater possession in the middle offensive zone is a good indicator of success in the offensive game, allowing us to predict a greater chance of victory in the match. Specifically, every time the teams achieve possession in the middle offensive zone, the chance of winning the match will increase 1.72 times and, the probability of winning the match making longer possessions in the middle offensive zone is 44.25%. Applying the Kruskal-Wallis test we have also been able to verify how match status modulates the teams possession time, specifically, when teams are winning they have longer possessions x2 = 92.628, p = 0.011. Results obtained are expected to help gain more knowledge about successful offensive game models, as well as performance factors of the offensive phase, which will allow teams to optimize their training process and performance during the match.


American Football
#1 CPR performance in the presence of audiovisual feedback or football shoulder pads
Reference: BMJ Open Sport Exerc Med. 2017 Jul 24;3(1):e000208. doi: 10.1136/bmjsem-2016-000208. eCollection 2017.
Authors: Tanaka S, Rodrigues W, Sotir S, Sagisaka R, Tanaka H
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5530121/pdf/bmjsem-2016-000208.pdf
Summary: The initiation of cardiopulmonary resuscitation (CPR) can be complicated by the use of protective equipment in contact sports, and the rate of success in resuscitating the patient depends on the time from incident to start of CPR. The aim of our study was to see if (1) previous training, (2) the presence of audiovisual feedback and (3) the presence of football shoulder pads (FSP) affected the quality of chest compressions. Six basic life support certified athletic training students (BLS-ATS), six basic life support certified emergency medical service personnel (BLS-EMS) and six advanced cardiac life support certified emergency medical service personnel (ACLS-EMS) participated in a crossover manikin study. A quasi-experimental repeated measures design was used to measure the chest compression depth (cm), rate (cpm), depth accuracy (%) and rate accuracy (%) on four different conditions by using feedback and/or FSP. Real CPR Help manufactured by ZOLL (Chelmsford, Massachusetts, USA) was used for the audiovisual feedback. Three participants from each group performed 2 min of chest compressions at baseline first, followed by compressions with FSP, with feedback and with both FSP and feedback (FSP+feedback). The other three participants from each group performed compressions at baseline first, followed by compressions with FSP+feedback, feedback and FSP. CPR performance did not differ between the groups at baseline (median (IQR), BLS-ATS: 5.0 (4.4-6.1) cm, 114(96-131) cpm; BLS-EMS: 5.4 (4.1-6.4) cm, 112(99-131) cpm; ACLS-EMS: 6.4 (5.7-6.7) cm, 138(113-140) cpm; depth p=0.10, rate p=0.37). A statistically significant difference in the percentage of depth accuracy was found with feedback (median (IQR), 13.8 (0.9-49.2)% vs 69.6 (32.3-85.8)%; p=0.0002). The rate accuracy was changed from 17.1 (0-80.7)% without feedback to 59.2 (17.3-74.3)% with feedback (p=0.50). The use of feedback was effective for depth accuracy, especially in the BLS-ATS group, regardless of the presence of FSP (median (IQR), 22.0 (7.3-36.2)% vs 71.3 (35.4-86.5)%; p=0.0002). The use of audiovisual feedback positively affects the quality of the depth of CPR. Both feedback and FSP do not alter the rate measurements. Medically trained personnel are able to deliver the desired depth regardless of the presence of FSP even though shallower chest compressions depth can be seen in CPR with FSP. A feedback device must be introduced into the athletic training settings.


#2 A comparison of the technique of the football quarterback pass between high school and university athletes
Reference: J Strength Cond Res. 2017 Jul 28. doi: 10.1519/JSC.0000000000002068. [Epub ahead of print]
Authors: Toffan A, Alexander MJL, Peeler J
Summary: The purpose of the study was to compare the most effective joint movements, segment velocities and body positions to perform the fastest and most accurate pass of high school and university football quarterbacks. Secondary purposes were to develop a quarterback throwing test to assess skill level, to determine which kinematic variables were different between high school and university athletes as well as to determine which variables were significant predictors of quarterback throwing test performance. Ten high school and ten university athletes were filmed for the study, performing nine passes at a target and two passes for maximum distance. Thirty variables were measured using Dartfish Team Pro 4.5.2 video analysis system, and Microsoft Excel was used for statistical analysis. University athletes scored slightly higher than the high school athletes on the throwing test, however this result was not statistically significant. Correlation analysis and forward stepwise multiple regression analysis was performed on both the high school players and the university players in order to determine which variables were significant predictors of throwing test score. Ball velocity was determined to have the strongest predictive effect on throwing test score (r = 0.900) for the high school athletes, however, position of the back foot at release was also determined to be important (r = 0.661) for the university group. Several significant differences in throwing technique between groups were noted during the pass, however, body position at release showed the greatest differences between the two groups. High school players could benefit from more complete weight transfer and decreased throw time to increase throwing test score. University athletes could benefit from increased throw time and greater range of motion in external shoulder rotation and trunk rotation to increase their throwing test score. Coaches and practitioners will be able to use the findings of this research to help improve these and related throwing variables in their high school and university quarterbacks.


#3 A Comparison of Pre-Season and In-Season Practice and Game Loads in NCAA Division I Football Players
Reference: J Strength Cond Res. 2017 Jul 31. doi: 10.1519/JSC.0000000000002173. [Epub ahead of print]
Authors: Wellman AD, Coad SC, Flynn PJ, Siam TK, McLellan CP
Summary: The aim of the present study was to quantify the individual practice and game loads throughout an NCAA division I football season to determine if significant differences exist between the practice loads associated with pre-season training camp and those undertaken during the in-season period. Thirty-one NCAA division I football players were monitored using GPS and IA (MinimaxX S5; Catapult Innovations, Melbourne, Australia) during 22 pre-season practices, 36 in-season practices, and 12 competitions. The season was divided into four distinct phases for data analysis: pre-season week 1 (pre-season1), pre-season week 2 (pre-season2), pre-season week 3 (pre-season3), and 12 in-season weeks. Individual IA datasets represented players from every offensive and defensive position group (WR: n=5), (OL: n=4), (RB: n=4), (QB: n=2), (TE: n=3), (DL: n=4), (LB: n=4), (DB: n=5). Data were set at the practice level, where an observation for each player's maximum player load (PLMax) or mean player load (PLMean) from each training camp phase was referenced against each player's respective PL from each game, Tuesday, Wednesday, or Thursday practice session. Notable results included significantly (p<0.05) greater PLMax values attributed to pre-season1 compared to PL resulting from all in-season practices, and significantly (p<0.05) higher cumulative PL reported for pre-season1, 2, and 3 compared to every in-season week. Data from the present study augment our understanding of the practice demands experienced by NCAA division I college football players, and provide scope for the improvement of pre-season practice design and physical conditioning strategies for coaches seeking to optimize performance.


#4 Performance and Return to Sport After Nonoperative Treatment of Clavicle Fractures in National Football League Players
Reference: Orthopedics. 2017 Aug 3:1-8. doi: 10.3928/01477447-20170719-03. [Epub ahead of print]
Authors: Jack RA 2nd, Sochacki KR, Navarro SM, McCulloch PC, Lintner DM, Harris JD.
Summary: Clavicle fractures are often seen in contact sports. The purpose of this study was to determine (1) return-to-sport (RTS) rate of National Football League (NFL) players following nonoperative treatment of clavicle fractures, (2) posttreatment career length and games per season, (3) pre- and posttreatment performance, and (4) posttreatment performance compared with control players matched by position, age, years of experience, and performance. Public records were used to identify NFL players who underwent nonoperative treatment of clavicle fractures. Demographic and performance data were collected for each player. Matched controls (position, age, experience, and performance) were identified. Control and case performance scores were calculated using a standardized scoring system. Return to sport was defined as playing a minimum of 1 game after treatment. Comparisons between the 2 groups and pre- and posttreatment time points were made using paired-samples Student's t tests. Thirty players (32 fractures) were analyzed. Two players fractured their contralateral clavicle. Of the players analyzed, 96.9% were able to RTS at a mean of 244.6±119.6 days. Eight players (27.6%) returned within the same season as their injury. Overall 1-year survival rate posttreatment was 93.5%. Players with nonoperative treatment had career lengths similar to those of controls (P>.05). No significant (P>.05) differences existed in demographic, performance, or games per season data between position groups for cases and matched controls pretreatment and preindex and in posttreatment compared with pretreatment performance scores. Wide receivers played fewer games per season (P=.043) following treatment. No position group had significantly worse posttreatment performance scores when compared with postindex matched controls.


Australian Football
#1 Inter- and intra-rater reliability of the Athletic Ability Assessment in sub-elite Australian Rules football players
Reference: J Strength Cond Res. 2017 Jul 31. doi: 10.1519/JSC.0000000000002175. [Epub ahead of print]
Authors: Rogers DK, McKeown I, Parfitt G, Burgess D, Eston RG.
Summary: The aim of this study was to determine the inter- and intra-rater rater reliability of the Athletic Ability Assessment (AAA) in sub-elite Australian Rules football (ARF) players. Eighteen male ARF players completed the AAA movement assessment (overhead squat, double lunge [left and right], single leg Romanian deadlift [left and right], chin-up and push-up), on two occasions separated by one week. During the first movement assessment players were filmed in the frontal and sagittal planes. Ten raters took part in the study (one experienced rater and nine novices) and were assigned in a quasi-random manner, to complete either (a) real-time assessment on two occasions, (b) real-time assessment on one occasion or (c) video-based assessment on two occasions. When assessed in real-time, of the 7 component movements of the AAA, raters registered moderate or greater intra-rater agreement on between 2 and 5 occasions. Intraclass correlation coefficients (ICC) of between 0.50 and 0.61 for the AAA total score indicated poor real-time intra-rater reliability for this variable. When assessed by video-recording, raters registered moderate or greater intra-rater agreement on between 6 and 7 occasions. The ICC for total score ranged between 0.60 and 0.93. Overall poor inter-rater reliability was evident for AAA component movements regardless of whether it was assessed in real-time or from video. Findings suggest the AAA is most reliably employed when assessed via video. It is recommended that if comparison between multiple raters is desired, a stringent training process be applied so that the interpretation of AAA scoring criteria is standardised across raters.


#2 Concussion guideline implementation perceptions and experiences among parents of community-level Australian Football junior players
Reference: BMJ Open Sport Exerc Med. 2017 Apr 22;3(1):e000215. doi: 10.1136/bmjsem-2016-000215. eCollection 2017.
Authors: White PE, Register-Mihalik J, Donaldson A, Sullivan SJ, Finch CF
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5530102/pdf/bmjsem-2016-000215.pdf
Summary: Concussion guidelines exist for multiple community sports. Parents are key stakeholders in guideline implementation and in appropriate responses following concussive injury. The purpose of this qualitative investigation was to understand how parents of community-level Australian Football (AF) players experience and perceive concussion guidelines in order to inform the design and implementation of concussion guidelines in community sport. A cross-sectional qualitative approach was adopted to allow for an open and detailed exploration of the views of parents of junior community AF players (ie, those aged <16 years) regarding concussion guidelines of the AF League (AFL)-the national governing body for AF. Participants were 15 parents of junior community AF players from two clubs affiliated with a large regional community AF League. The key experiences and perceptions of the parents included appreciation that the guidelines outlined the postconcussion process that should be followed, desires for better understanding of the guidelines by general practitioners (ie, medical doctors) who care for children with concussion, having more readily available information for parents and receiving more formal policy guiding timing of return-to-participation following concussion. Difficulties with the guidelines not addressing delayed presentations of concussion were also frequently mentioned. Parents are key stakeholders in concussion prevention and care in community sport. As such, their input should be considered when developing guidelines and resources for community sport. Furthermore, concussion information should be made available to parents in an easily accessible and community-friendly form.

Mon

07

Aug

2017

Latest research in football - week 30 - 2017

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 The preventive effect of a soccer-specific ankle brace on acute lateral ankle sprains in girls amateur soccer players: study protocol of a cluster-randomised controlled trial
Reference: Inj Prev. 2017 Jul 27. pii: injuryprev-2017-042465. doi: 10.1136/injuryprev-2017-042465. [Epub ahead of print]
Authors: Thijs K, Huisstede B, Goedhart E, Backx F
Summary: Acute lateral ankle sprains are the single most often diagnosed injury in female soccer players and often result in an inability to play. This highlights the need for effective prevention strategies. Proprioceptive training and/or the use of an external support to decrease inversion of the ankle joint can prevent or reduce the number of acute lateral ankle sprains. The effectiveness of a soccer-specific ankle brace in reducing first-time and recurrent acute lateral ankle sprains has never been investigated in girl soccer players. If effective, ankle braces could be introduced into soccer. Girl amateur soccer players (aged 14-18 years) will be allocated to an intervention or control group. The intervention group will be instructed to wear soccer-specific ankle braces on both ankles during soccer training and matches; the control group will continue playing soccer as usual. Primary outcomes are the incidence and severity of acute lateral ankle sprains. Secondary outcomes are the prognostic value of generalised joint hypermobility and functional stability on the risk of acute lateral ankle sprains and compliance with the intervention. The findings from this study may provide evidence to support the use of a soccer-specific ankle brace to prevent lateral ankle sprains during soccer. We hypothesise that this brace will reduce the incidence of ankle sprains among young amateur girl soccer players by 50%. The prevention of such injuries will be beneficial to players, clubs and society.


#2 The use of metabolic power to assess physical demands in soccer: how does it differ from the traditional approach through speed running?
Reference: J Sports Med Phys Fitness. 2017 Jul 25. doi: 10.23736/S0022-4707.17.07563-6. [Epub ahead of print]
Authors: Martinez-Cabrera FI, Nunez-Sanchez FJ
Summary: Metabolic power and speed running are in the top-10-ranked variables used to quantify the physical demand in soccer matches or training practices. The purpose of this study were 1) to compare metabolic power (MP) and the traditional approach using speed running during soccer matches in absolute values and 2) in zones of intensity in function of the playing positions. Thirty-eight professional soccer players were analysed during 18 friendly matches from 4 preseasons (n=300) and divided into 5 groups of playing positions: central defender (CD) (n=64), wide defender (WD) (n=55), central midfielder (CM) (n=58), wide attacker (WA) (n=70) and attacker (AT) (n=53). The individual profiles to each playing positions were assessed using MP and speed running approaches. The magnitude of change was substantial when there was a ≥75% likelihood of the effect. The effect size was also calculated using a confidence interval of 90%. In absolute values, CMs and WAs had substantially greater values than did the other positions, with CMs having the highest values in both approaches and an identical relationship between the positions in both approaches. In categories of intensity, medium-low intensity displayed differences between the approaches; the physical demands of ATs and CDs were lower using the traditional approach but were higher than the other playing positions when assessed using MP. No differences were found at low, medium or high intensities. The MP and energy expenditure reported differences at medium-low intensity compared to the speed running traditional approach between playing positions. However, the other intensities did not report differences compared to the traditional approach in the different playing positions.


#3 The relationship between movement speed and duration during soccer matches
Reference: PLoS One. 2017 Jul 25;12(7):e0181781. doi: 10.1371/journal.pone.0181781. eCollection 2017.
Authors: Roecker K, Mahler H, Heyde C, Roll M, Gollhofer A
Download link: http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0181781&type=printable
Summary: The relationship between the time duration of movement (t(dur)) and related maximum possible power output has been studied and modeled under many conditions. Inspired by the so-called power profiles known for discontinuous endurance sports like cycling, and the critical power concept of Monod and Scherrer, the aim of this study was to evaluate the numerical characteristics of the function between maximum horizontal movement velocity (HSpeed) and t(dur) in soccer. To evaluate this relationship, GPS data from 38 healthy soccer players and 82 game participations (≥30 min active playtime) were used to select maximum HSpeed for 21 distinct t(dur) values (between 0.3 s and 2,700 s) based on moving medians with an incremental t(dur) window-size. As a result, the relationship between HSpeed and Log(t(dur)) appeared reproducibly as a sigmoidal decay function, and could be fitted to a five-parameter equation with upper and lower asymptotes, and an inflection point, power and decrease rate. Thus, the first three parameters described individual characteristics if evaluated using mixed-model analysis. This study shows for the first time the general numerical relationship between t(dur) and HSpeed in soccer games. In contrast to former descriptions that have evaluated speed against power, HSpeed against t(dur) always yields a sigmoidal shape with a new upper asymptote. The evaluated curve fit potentially describes the maximum moving speed of individual players during the game, and allows for concise interpretations of the functional state of team sports athletes.


#4 Relevance of whole body virabtion exercise in sport: A short review with soccer, diver and combat sport
Reference: Afr J Tradit Complement Altern Med. 2017 Jul 7;14(4 Suppl):19-27. doi: 10.21010/ajtcam.v14i4S.3. eCollection 2017.
Authors: Morel DS, Dionello CDF, Moreira-Marconi E, Brandao-Sobrinho-Neto S, Paineiras-Domingos LL, Souza PL, Sa-Caputo DDC, Dias G, Figueiredo C, Carmo RCR, Paiva PC, Sousa-Goncalves CR, Kutter CR, Guedes-Aguiar EO, Cloak R, Bernardo-Filho M
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5514442/pdf/AJTCAM-14-19.pdf
Summary: Whole body vibration exercise (WBVE) has been used as a safe and accessible exercise and important reviews have been published about the use of this exercise to manage diseases and to improve physical conditions of athletes The aim of this paper is to highlight the relevance of WBVE to soccer players, divers and combat athletes. This study was made through a systematic review of publications involving WBVE and the selected sports in two databases (Pubmed and PEDRo). It were identified 10 studies involving WBVE and sports (6 of soccer, 2 of diving and 2 of sport combat) with 156 subjects (80 soccer players, 32 divers and 44 combat athletes), with age from 17 to 44 years old. The use of WBVE has proven to be a safe and useful strategy to improve the physical conditions of players of different sports. These findings may have clinical relevance and should be considered as a strategy to be used to try improve the physical conditions of players.


#5 Benign paroxysmal positional vertigo (BPPV) diagnosis and treatment in an elite professional football (soccer) player
Reference: BMJ Case Rep. 2017 Jul 24;2017. pii: bcr-2017-220000. doi: 10.1136/bcr-2017-220000.
Authors: Burrows L, Price R
Summary: A 33-year-old male professional football player suffered from acute-onset dizziness following a lower limb soft tissue treatment in prone lying. Symptoms included spinning vertigo lasting for 30's, headache, visual vertigo and disorientation. Clinical examination of balance and vestibular systems confirmed a left posterior canalithiasis benign paroxysmal positional vertigo (BPPV) and excluded other central and peripheral causes of dizziness. Two cycles of a left Epley manoeuvre were performed. An Epley manoeuvre abolished the BPPV and negated the need for medication. The player was able to return to play without dizziness within 24 hours completely symptom free. BPPV can be successfully identified and treated in elite football players and they can see a return to training and games within 24 hours. There are no epidemiology studies for this group of elite athletes either male or female despite increased occupational risk factors.


#6 Opportunities and Benefits for Powerchair Users Through Power Soccer
Reference: Adapt Phys Activ Q. 2017 Jul;34(3):235-255. doi: 10.1123/apaq.2016-0022.
Authors: Jeffress MS, Brown WJ
Summary: Power soccer (or powerchair football), the first competitive team sport for users of motorized wheelchairs, is receiving increased attention among people with disabilities, healthcare professionals, and academics. The present study provides a qualitative analysis of the experiences of 34 American power soccer athletes. Participant observation and in-depth interviews with 11 female and 23 male athletes were conducted between 2007 and 2013. Results indicate that involvement in power soccer provides participants with an increased sense of empowerment, acquisition of social capital, and psychosocial benefits, including a deep satisfaction of the desire to participate in competitive sports and an opportunity to be independent. Implications of these findings for improving the quality of life of people with physical disabilities and for future research are discussed.


#7 Biomechanical differences in female basketball and soccer players during multi-directional jump landings
Reference: J Strength Cond Res. 2017 Jul 14. doi: 10.1519/JSC.0000000000001785. [Epub ahead of print]
Authors: Taylor JB, Ford KR, Schmitz RJ, Ross SE, Ackerman TA, Shultz SJ.
Summary: Anterior cruciate ligament injury prevention programs are less successful in basketball than soccer and may be due to distinct movement strategies that these athletes develop from sport-specific training. The purpose of this study was to identify biomechanical differences between female basketball and soccer players during multi-directional jump landings. Lower extremity biomechanics of eighty-nine female athletes who played competitive basketball (n=40) or soccer (n=49) at the middle- or high-school level were analyzed with three-dimensional motion analysis during a drop vertical jump (DVJ), double- (SAG-DL) and single-leg forward jump (SAG-SL), and double- (FRONT-DL) and single-leg (FRONT-SL) lateral jump. Basketball players landed with less hip and/or knee excursion during all tasks (p<.05) except for the SAG-SL task, where basketball players landed with greater peak hip flexion angles (p=.04). The FRONT-SL task elicited the most distinct sport-specific differences, including decreased hip adduction (p<.001) angles, increased hip internal rotation (p=.003), and increased relative knee external rotation (p=.001) excursions in basketball players. Additionally, the FRONT-SL task elicited greater forces in knee abduction (p=.003) and lesser forces in hip adduction (p=.001) and knee external rotation (p<.001) in basketball players. Joint energetics were different during the FRONT-DL task, as basketball players exhibited less sagittal plane energy absorption at the hip (p<.001), and greater hip (p<.001) and knee (p=.001) joint stiffness. Sport-specific movement strategies were identified during all jump landing tasks, such that soccer players exhibited a more protective landing strategy than basketball players, justifying future efforts toward sport-specific ACL injury prevention programs.


#8 Somatotype And Body Composition In Young Soccer Players According To The Playing Position And Sport Success
Reference: J Strength Cond Res. 2017 Jul 17. doi: 10.1519/JSC.0000000000002125. [Epub ahead of print]
Authors: Cardenas-Fernandez V, Chinchilla-Minguet JL, Castillo-Rodriguez A
Summary: Soccer players undergo an evolution in their body composition throughout the growth and passage through the different base stages, that is, childhood, puberty and adolescence. The aim of this study was to analyze the morphology and body composition of U14, U16, and U19 soccer players, taking into account in addition, their sport success endorsed through the regularity participation and their relation with the different playing positions occupied during competition (goalkeeper, external defender, central defender, midfielder and forward/extreme). For that, a total of 174 male young soccer players were evaluated anthropometrically. Dominant somatotype of the players was, according to their playing position: meso-endomorphic in goalkeepers, central for external defenders, balanced ectomorph in central defenders, balanced mesomorph in the case of midfielders, and meso-ectomorph in forwards/extremes. Taking into account that sport performance is directly mediated by the body composition of athletes, the differences found suggest a marked specialization between the goalkeepers and forwards, establishing significant differences between them. Further studies would be needed to evaluate the influence of individual maturation development versus sports training on the conformation of a certain anthropometric profile of a soccer player and its relation with the different playing positions occupied on the pitch during the game.


#9 A Pilot Study of the Effect of Outsole Hardness on Lower Limb Kinematics and Kinetics during Soccer Related Movements
Reference: J Hum Kinet. 2017 Jun 22;57:17-27. doi: 10.1515/hukin-2017-0043. eCollection 2017 Jun.
Authors: Sun D, Mei Q, Baker JS, Jia X, Gu Y
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5504575/pdf/hukin-57-017.pdf
Summary: The purpose of this study was to investigate the effect of different outsole hardness of turf cleats shoes on the lower limb kinematics and kinetics of soccer players playing on artificial turf. The participants were required to complete tasks of straight running and 45° left sidestep cutting movements, respectively, at the speed of 4.5 ± 0.2 m/s on artificial turf. They were asked to randomly select turf cleats shoes with a soft outsole (SO), medium hardness outsole (MO) and hard outsole (HO). During the stance phase of straight running, peak pressure and force-time integral in medial forefoot (MFF) of players wearing cleats shoes with MO were significantly higher than those wearing cleats shoes with SO. During the stance phase of a 45° cutting maneuver, players wearing cleats shoes with SO showed significantly higher peak knee flexion and abduction angles than the HO group. Players wearing cleats shoes with SO also showed higher ankle dorsiflexion and inversion angles compared with those wearing cleats shoes with HO. The vertical average loading rate (VALR) as well as peak pressure and force-time integral in the heel (H) and lateral forefoot (LFF) regions of players wearing cleats shoes with HO were significantly higher than those wearing shoes with SO. On the contrary, peak pressure and force-time integral of players wearing shoes with SO were significantly higher than those wearing shoes with HO in MFF. A higher vertical loading rate and plantar pressure of some areas may increase the potential risk of metatarsal stress fractures and plantar fasciitis. Therefore, this finding about turf cleats shoes could give some theoretic support for the design of turf cleats shoes and material optimization in the future.


#10 Cardiopulmonary Performance During Maximal Exercise in Soccer Players with Alterations in Renal Function
Reference: J Hum Kinet. 2017 Jun 22;57:107-115. doi: 10.1515/hukin-2017-0052. eCollection 2017 Jun.
Summary: Morales AP, Sampaio-Jorge F, da Cruz Rangel LF, de Souza Menezes J, Leite TC, Ribeiro BG
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5504583/pdf/hukin-57-107.pdf
Summary: The aim of this study was to evaluate the curves of cardiorespiratory variables during cardiopulmonary exercise testing (CPET) in soccer players who had acute alterations in the glomerular filtration rate (GFR) after performing the pre-season training protocol. Sixteen male professional soccer players (25 ± 3 years; 179 ± 2 cm; and 77 ± 6 kg) were evaluated for oxygen uptake (VO2), heart rate (HR) and pulse relative oxygen (relative O2 Pulse) curves with intervals corresponding to 10% of the total duration of CPET. Athletes were grouped according to the GFR and classified as decreased GFR (dGFR; n = 8) and normal GFR (nGFR; n = 8). Athletes from the dGFR group exhibited lower VO2 values (p < 0.05) when 90% (dGFR 49.8 ± 4.0 vs. nGFR 54.4 ± 6.1 ml·kg-1·min-1) and 100% (dGFR 52.6 ± 4.1 vs. nGFR 57.4 ± 5.9 ml·kg-1·min-1) of the test was complete; HR high values (p < 0.05) when 90% (dGFR 183.7 ± 5.1 vs. nGFR 176.6 ± 4.8 bpm-1) and 100% (dGFR 188.1 ± 5.0 vs. nGFR 180.8 ± 4.8 bpm-1) of the test was complete; and lower relative O2 Pulse values (p < 0.05) when 70% (dGFR 25.6 ± 8.4 vs. nGFR 27.9 ± 9.7 ml·beat-1·kg-1), 80% (dGFR 26.6 ± 8.8 vs. nGFR 29.1 ± 10.0 ml·beat-1·kg-1), 90% (dGFR 27.1 ± 9.0 vs. nGFR 30.8 ± 10.6 ml·beat-1·kg-1) and 100% (dGFR 28 ± 9.2 vs. nGFR 31.8 ± 10.9 ml·beat-1·kg-1) of the test was complete. A correlation was found (r = -0.66, R2 = 0.44, p = 0.00) between lower VO2 peak and elevated levels of urinary protein excretion. In conclusion, soccer players with reduced kidney function after performing the pre-season training protocol also presented alterations in cardiopulmonary variables. We suggest that monitoring of renal function may be used to identify less conditioned soccer players.

Sat

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Jul

2017

Latest research in football - week 29 - 2017

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 Field location and player roles as constraints on emergent 1-vs-1 interpersonal patterns of play in football
Reference: Hum Mov Sci. 2017 Jul 5;54:347-353. doi: 10.1016/j.humov.2017.06.008. [Epub ahead of print]
Authors: Laakso T, Travassos B, Liukkonen J, Davids K
Summary: This study examined effects of player roles on interpersonal patterns of coordination that sustain decision-making in 1-vs-1 sub-phases of football in different field locations near the goal (left-, middle- and right zone). Participants were fifteen U-16yrs players from a local competitive amateur team. To measure interpersonal patterns of coordination in the 1-vs-1 dyads we recorded: (i) the relative distance value between each attacker and defender to the centre of the goal, and (ii), the relative angle between the centre of the goal, each defender and attacker. Results revealed how variations in field locations near the goal (left-, middle- and right-zones) constrained the relative distance and relative angle values that emerged between them and the goal. It reveals that relative position of the goal is a key informational variable that sustained participants' behaviours for dribbling and shooting. Higher values of relative distance and angle were observed in the middle zone, compared to other zones. Players' roles also constitute a constraint on the interpersonal coordination for dribbling and shooting. Additionally, it seems that players' foot preference constrains the dynamics of interpersonal patterns of coordination between participants, especially in left and right zones. The findings suggest that to increase participants' opportunities for action, coaches should account with field positions, players' roles and preference foot.


#2 Influence of Cleats-Surface Interaction on the Performance and Risk of Injury in Soccer: A Systematic Review
Reference: Appl Bionics Biomech. 2017;2017:1305479. doi: 10.1155/2017/1305479. Epub 2017 Jun 8.
Authors: Silva DCF, Santos R, Vilas-Boas JP, Macedo R, Montes AM, Sousa ASP
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5480019/pdf/ABB2017-1305479.pdf
Summary: The purpose of the study was to review the influence of cleats-surface interaction on the performance and risk of injury in soccer athletes. Full experimental and original papers, written in English that studied the influence of soccer cleats on sports performance and injury risk in artificial or natural grass. Twenty-three articles were included in this review: nine related to performance and fourteen to injury risk. On artificial grass, the soft ground model on dry and wet conditions and the turf model in wet conditions are related to worse performance. Compared to rounded studs, bladed ones improve performance during changes of directions in both natural and synthetic grass. Cleat models presenting better traction on the stance leg improve ball velocity while those presenting a homogeneous pressure across the foot promote better kicking accuracy. Bladed studs can be considered less secure by increasing plantar pressure on lateral border. The turf model decrease peak plantar pressure compared to other studded models. The soft ground model provides lower performance especially on artificial grass, while the turf model provides a high protective effect in both fields.


#3 Deviating running kinematics and hamstring injury susceptibility in male soccer players: Cause or consequence?
Reference: Gait Posture. 2017 Jun 27;57:270-277. doi: 10.1016/j.gaitpost.2017.06.268. [Epub ahead of print]
Authors: Schuermans J, Van Tiggelen D, Palmans T, Danneels L, Witvrouw E
Summary: Although the vast majority of hamstring injuries in male soccer are sustained during high speed running, the association between sprinting kinematics and hamstring injury vulnerability has never been investigated prospectively in a cohort at risk. This study aimed to objectify the importance of lower limb and trunk kinematics during full sprint in hamstring injury susceptibility. At the end of the 2013 soccer season, three-dimensional kinematic data of the lower limb and trunk were collected during sprinting in a cohort consisting of 30 soccer players with a recent history of hamstring injury and 30 matched controls. Subsequently, a 1.5 season follow up was conducted for (re)injury registry. Ultimately, joint and segment motion patterns were submitted to retro- and prospective statistical curve analyses for injury risk prediction. Statistical analysis revealed that index injury occurrence was associated with higher levels of anterior pelvic tilting and thoracic side bending throughout the airborne (swing) phases of sprinting, whereas no kinematic differences during running were found when comparing players with a recent hamstring injury history with their matched controls. Deficient core stability, enabling excessive pelvis and trunk motion during swing, probably increases the primary injury risk. Although sprinting encompasses a relative risk of hamstring muscle failure in every athlete, running coordination demonstrated to be essential in hamstring injury prevention.


#4 Effects of lower-limb strength training on agility, repeated sprinting with changes of direction, leg peak power, and neuromuscular adaptations of soccer players
Reference: J Strength Cond Res. 2017 Jan 24. doi: 10.1519/JSC.0000000000001813. [Epub ahead of print]
Authors: Hammami M, Negra Y, Billaut F, Hermassi S, Shephard RJ, Chelly MS
Summary: We examined the effects on explosive muscular performance of incorporating 8 weeks strength training into the preparation of junior male soccer players, allocating subjects between an experimental group (E, n=19) and a matched control group (C, n=12). Controls maintained their regular training program, but the experimental group replaced a part of this schedule by strength training. Performance was assessed using running times (5m, 10m, 20m, 30 and 40m), a sprint test with 180° turns (S180°), a 9-3-6-3-9 m sprint with backward and forward running (SBF), a 4 x 5 m sprint test with turns, repeated shuttle sprinting, repeated changes of direction, squat (SJ) and counter-movement (CMJ) jumping, back half-squatting, and a force-velocity test. Electromyographic (EMG) activity of the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) muscles was recorded during jumping. Two-way ANOVA showed significant gains in E relative to C during the straight sprint (all distances). Scores of E increased substantially (p≤0.01) on S4 x 5 and SBF, and moderately on S180°. Leg peak power, SJ and CMJ were also enhanced, with significant increases in EMG activity. However, repeated-sprint parameters showed no significant changes. We conclude that biweekly strength training improves key components of performance in junior soccer players relative to standard in-season training.


#5 Physiological Characteristics of Projected Starters and Non-Starters in the Field Positions from a Division I Women's Soccer Team
Reference: Int J Exerc Sci. 2017 Jul 1;10(4):568-579. eCollection 2017.
Authors: Risso FG, Jalilvand F, Orjalo AJ, Moreno MR, Davis DL, Birmingham-Babauta SA, Stokes JJ, Stage AA, Liu TM, Giuliano DV, Lazar A, Lockie RG
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5466405/pdf/ijes-10-04-568.pdf
Summary: NCAA soccer features different substitution rules compared to FIFA-sanctioned matches, with a greater availability of players who can enter the game. This could influence the physiological characteristics of the field position starters (ST) and non-starters (NST) within a collegiate women's team, which has not been previously analyzed. Thus, 22 field players from the same Division I women's soccer squad completed: vertical and standing broad jumps; 30-meter (m) sprint (0-5, 0-10, 0-30 m intervals); pro-agility and 60-yard shuttle; and the Yo-Yo Intermittent Recovery Test Level 1. Players were defined into ST (n=10) and NST (n=12) by the coaching staff. A one-way ANOVA derived any significant (p≤0.05) between-group differences, and effect sizes were used for a magnitude-based inference analysis. Z-scores were also calculated to document worthwhile differences above or below the squad mean for the groups. The results showed no significant between-group differences for any of the performance tests. ST did have a worthwhile difference above the squad mean in the 0-10 and 0-30 m sprint intervals, while NST had a worthwhile difference below the squad mean in the 0-30 m interval. Physiological characteristics between ST and NST from the analyzed Division I squad were similar, although ST were generally faster. The similarities between ST and NST may be a function of the team's training, in that all players may complete the same workouts. Nonetheless, if all players exhibit similar physiological capacities, with appropriate substitutions by the coach a collegiate team should be able to maintain a high work-rate throughout a match.


#5 Epidemiologic comparisons of soccer-related injuries presenting to emergency departments and reported within high school and collegiate settings
Reference: Inj Epidemiol. 2017 Dec;4(1):19. doi: 10.1186/s40621-017-0116-9. Epub 2017 Jul 3.
Authors: Kerr ZY, Pierpoint LA, Currie DW, Wasserman EB, Comstock RD
Summary: Few studies compare sports injury patterns in different settings. This study described the epidemiology of soccer injuries presenting to emergency departments (EDs) and compared injuries presenting to EDs to injuries presenting to collegiate and high school athletic trainers (ATs). Soccer-related injuries (product code 1267) in the National Electronic Injury Surveillance System (NEISS) that were sustained by individuals at least two years of age in 2004-2013 were included. High School Reporting Information Online (HS RIO) data for high school soccer injuries during the 2005/06-2013/14 academic years were compared to NEISS data for those aged 14-17 years in 2005-2013. National Collegiate Athletic Association Injury Surveillance Program (NCAA-ISP) data for collegiate soccer injuries during the 2009/10-2013/14 academic years were compared to NEISS data for those aged 18-22 years in 2009-2013. All datasets included weights to calculate national estimates. Injury proportion ratios (IPRs) with 95% confidence intervals (CIs) compared nationally estimated injury distributions between the HS RIO/NCAA-ISP and NEISS data subsets. During the study period, 63,258 soccer-related injuries were captured by NEISS, which translates to an estimated 2,039,250 injuries seen at US EDs nationwide. Commonly injured body parts included the head/face (19.1%), ankle (17.6%), hand/wrist (15.3%), and knee (12.2%). Common diagnoses included sprains/strains (34.0%), fractures (22.2%), and contusions (17.7%). Compared to their respective age ranges in NEISS, sprains/strains comprised a larger proportion of injuries in HS RIO (48.3% vs. 33.7%; IPR = 1.38; 95% CI: 1.33, 1.42) and NCAA-ISP (51.3% vs. 37.0%; IPR = 1.39; 95% CI: 1.31, 1.46). In contrast, fractures comprised a smaller proportion of injuries in HS RIO than in NEISS (7.5% vs. 18.6%; IPR = 0.43; 95% CI: 0.39, 0.47) and NCAA-ISP (2.8% vs. 15.7%; IPR = 0.18; 95% CI: 0.14, 0.22). ATs more commonly reported injuries that are easily diagnosed and treated (e.g., sprains/strains); EDs more commonly reported injuries with longer recovery times and rehabilitation (e.g., fractures). Although ED surveillance data can identify the most severe sports-related injuries, high school and college sports surveillance may better describe the breadth of sports-related injuries. Our findings may provide further support for school-based sports medicine professionals, but further research is needed to comprehensively examine the potential economic and health-related benefits.


#6 Internal training load and its longitudinal relationship with seasonal player wellness in elite professional soccer
Reference: Physiol Behav. 2017 Jun 28;179:262-267. doi: 10.1016/j.physbeh.2017.06.021. [Epub ahead of print]
Authors: Clemente FM, Mendes B, Nikolaidis PT, Calvete F, Carriço S, Owen AL
Summary: Monitoring internal training load has been extensively used and described within team sport environments, however when compared to internal physiological measures such as heart rate (HR) and rating of perceived exertion (RPE), the literature is sparse. The primary aim of this investigation study was to assess differences of playing position on ITL, session-RPE and wellness across two different training microcycles (1 vs. 2 competitive games), in addition with examining the relationship between ITL and Hooper's Index across an entire season. Thirty-five professional soccer players from the Portuguese premier league participated in the study (25.7±5.0years; 182.3±6.4cm; 79.1±7.0kg). Analysis of variance revealed higher values of DOMS (Means(M): 3.33 vs. 3.10; p=0.001; effect Size (ES)=0.087), fatigue (M: 3.18 vs. 2.99; p=0.001; ES=0.060) and HI (M: 11.85 vs. 11.56; p=0.045; ES=0.034) in 2-game weeks compared with 1-game weeks. Correlation between ITL and HI levels found significant negative correlations between ITL and DOMS (ρ=-0.156), ITL and sleep (ρ=-0.109), ITL and fatigue (ρ=-0.225), ITL and stress (ρ=-0.188), and ITL and HI (ρ=-0.238) in 2-game weeks. Results from 1-game microcycle only highlighted negative correlations between ITL and stress (ρ=-0.080). It was concluded from the study that greater fatigue potential, muscle soreness, stress and ITL was significantly more apparent within a 2-game microcycle. As a result, care should be taken when planning the lead into and out of a 2-game fixture microcycle highlighting key specific recovery strategies to damped the increased stress effect. Additionally, the potential utilization of squad rotation strategies may be a positive approach with aim of managing the fatigue effect.


#7 Epidemiology of time loss groin injuries in a men's professional football league: a 2-year prospective study of 17 clubs and 606 players
Reference: Br J Sports Med. 2017 Jun 30. pii: bjsports-2016-097277. doi: 10.1136/bjsports-2016-097277. [Epub ahead of print]
Authors: Mosler AB, Weir A, Eirale C, Farooq A, Thorborg K, Whiteley RJ, Hӧlmich P, Crossley KM
Summary: Groin injury epidemiology has not previously been examined in an entire professional football league. We recorded and characterised time loss groin injuries sustained in the Qatar Stars League. Male players were observed prospectively from July 2013 to June 2015. Time loss injuries, individual training and match play exposure were recorded by club doctors using standardised surveillance methods. Groin injury incidence per 1000 playing hours was calculated, and descriptive statistics used to determine the prevalence and characteristics of groin injuries. The Doha agreement classification system was used to categorise all groin injuries. 606 footballers from 17 clubs were included, with 206/1145 (18%) time loss groin injuries sustained by 150 players, at an incidence of 1.0/1000 hours (95% CI 0.9 to 1.1). At a club level, 21% (IQR 10%-28%) of players experienced groin injuries each season and 6.6 (IQR 2.9-9.1) injuries were sustained per club per season. Of the 206 injuries, 16% were minimal (1-3 days), 25% mild (4-7 days), 41% moderate (8-28 days) and 18% severe (>28 days), with a median absence of 10 days/injury (IQR 5-22 days). The median days lost due to groin injury per club was 85 days per season (IQR 35-215 days). Adductor-related groin pain was the most common entity (68%) followed by iliopsoas (12%) and pubic-related (9%) groin pain. Groin pain caused time loss for one in five players each season. Adductor-related groin pain comprised 2/3 of all groin injuries. Improving treatment outcomes and preventing adductor-related groin pain has the potential to improve player availability in professional football.


American Football
#1 Association of Playing High School Football With Cognition and Mental Health Later in Life
Reference: JAMA Neurol. 2017 Jul 3. doi: 10.1001/jamaneurol.2017.1317. [Epub ahead of print]
Authors: Deshpande SK, Hasegawa RB, Rabinowitz AR, Whyte J, Roan CL, Tabatabaei A, Baiocchi M, Karlawish JH, Master CL, Small DS
Summary: American football is the largest participation sport in US high schools and is a leading cause of concussion among adolescents. Little is known about the long-term cognitive and mental health consequences of exposure to football-related head trauma at the high school level. The purpose was to estimate the association of playing high school football with cognitive impairment and depression at 65 years of age. A representative sample of male high school students who graduated from high school in Wisconsin in 1957 was studied. In this cohort study using data from the Wisconsin Longitudinal Study, football players were matched between March 1 and July 1, 2017, with controls along several baseline covariates such as adolescent IQ, family background, and educational level. For robustness, 3 versions of the control condition were considered: all controls, those who played a noncollision sport, and those who did not play any sport. A composite cognition measure of verbal fluency and memory and attention constructed from results of cognitive assessments administered at 65 years of age. A modified Center for Epidemiological Studies' Depression Scale score was used to measure depression. Secondary outcomes include results of individual cognitive tests, anger, anxiety, hostility, and heavy use of alcohol. Among the 3904 men (mean [SD] age, 64.4 [0.8] years at time of primary outcome measurement) in the study, after matching and model-based covariate adjustment, compared with each control condition, there was no statistically significant harmful association of playing football with a reduced composite cognition score (-0.04 reduction in cognition vs all controls; 97.5% CI, -0.14 to 0.05) or an increased modified Center for Epidemiological Studies' Depression Scale depression score (-1.75 reduction vs all controls; 97.5% CI, -3.24 to -0.26). After adjustment for multiple testing, playing football did not have a significant adverse association with any of the secondary outcomes, such as the likelihood of heavy alcohol use at 65 years of age (odds ratio, 0.68; 95% CI, 0.32-1.43). Cognitive and depression outcomes later in life were found to be similar for high school football players and their nonplaying counterparts from mid-1950s in Wisconsin. The risks of playing football today might be different than in the 1950s, but for current athletes, this study provides information on the risk of playing sports today that have a similar risk of head trauma as high school football played in the 1950s.

 


#2 Return to Sport and Performance After Anterior Cruciate Ligament Reconstruction in National Football League Linemen
Reference: Orthop J Sports Med. 2017 Jun 20;5(6):2325967117711681. doi: 10.1177/2325967117711681. eCollection 2017 Jun.
Authors: Cinque ME, Hannon CP, Bohl DD, Erickson BJ, Verma NN, Cole BJ, Bach BR Jr
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5480637/pdf/10.1177_2325967117711681.pdf
Summary: Tears of the anterior cruciate ligament (ACL) are common in the National Football League (NFL). The impact of these injuries on the careers of NFL linemen is unknown. The purpose was to define the percentage of NFL linemen who return to sport (RTS) after ACL reconstruction, the mean time to RTS, and the impact on performance compared with matched controls. Data on NFL offensive and defensive linemen who sustained an ACL tear and underwent ACL reconstruction between 1980 and 2015 were analyzed. Players were identified through NFL team websites, publicly available injury reports, player profiles, and press releases. Demographics and mean in-game performance data preinjury and post-ACL reconstruction were recorded. A player was deemed to have returned to sport if he played in at least 1 NFL game after his ACL reconstruction. A healthy control group was selected to compare in-game performance data and was matched with the study group on several parameters. Overall, 73 NFL linemen met the inclusion criteria; 47 (64.3%) returned to play after ACL reconstruction (62.5% of offensive linemen, 65.9% of defensive linemen). All offensive linemen successfully returned to play the season after injury. No difference existed in number of seasons, total number of games played, mean number of games played, or mean number of games started per season when offensive linemen who RTS after ACL reconstruction were compared with matched controls (all P > .05). Among defensive linemen who RTS, most returned the season after injury (88.9%). There was no difference between defensive linemen who RTS after ACL reconstruction and matched controls in any performance metrics as an average over the remainder of their career (all P > .05). However, NFL defensive linemen who tore their ACL played fewer total seasons than matched controls (P = .020). Overall, 64.3% of NFL offensive and defensive linemen who undergo ACL reconstruction returned to play. Linemen who RTS do so at a high level, with no difference in in-game performance or career duration when compared with matched controls.


Australian Football
#1 Return to Play and Player Performance After Anterior Cruciate Ligament Injury in Elite Australian Rules Football Players
Reference: Orthop J Sports Med. 2017 Jun 21;5(6):2325967117711885. doi: 10.1177/2325967117711885. eCollection 2017 Jun.
Authors: Liptak MG, Angel KR
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5482352/pdf/10.1177_2325967117711885.pdf
Summary: Australian Rules football is a highly aerobic and anaerobic game that at times requires players to perform cutting or pivoting maneuvers, potentially exposing them to anterior cruciate ligament (ACL) injury. At present, there are limited data available addressing the impact of ACL injury on return to play and preinjury form after ACL reconstruction. The purpose was to determine the prevalence of ACL injury and the incidence of further ACL injury, and to consider player return to play and return to preinjury form after ACL reconstruction. It was hypothesized that elite-level Australian Football League (AFL) players do not return to preinjury form until, at minimum, 2 years after returning to play. A retrospective analysis was undertaken on a cohort of elite AFL players who injured their ACL between 1990 and 2000. Return to play after ACL reconstruction was determined by the mean number of ball disposals, or release of the ball by the hand or foot, at 1, 2, and 3 years after return to play and compared with preinjury form. Associations between player and injury characteristics, method of reconstruction, and outcomes (return to play, preinjury form, and further ACL injury) were examined. During the included seasons, a total of 2723 AFL players were listed. Of these, 131 (4.8%) sustained an ACL injury, with 115 players eligible for inclusion. Of 115 players, 26% did not return to elite competition, while 28% of those who did return experienced further ACL injury. The adjusted mean number of disposals (± standard error of the mean) was significantly lower at 1 year (12.21 ± 0.63; P = .003), 2 years (12.09 ± 0.65; P = .008), and 3 years (11.78 ± 0.77; P = .01) after return to play compared with preinjury (14.23 ± 0.67). On average, players did not return to preinjury form by 3 years (P < .01). Players aged 30 years or older were less likely to return to play compared with younger players (P = .0002), moderate-weight players were more likely to return to play compared with lighter-weight players (P = .007), and there were significantly increased odds of not returning to play if the dominant side was injured (odds ratio, 0.10; 95% CI, 0.03-0.34; P = .0002). On average, AFL players do not return to their preinjury form after ACL injury and reconstruction, a common injury in this sporting population. This along with the high occurrence of reinjury highlights the career-threatening nature of ACL injury for elite AFL players.

Sat

22

Jul

2017

Latest research in football - week 28 - 2017

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 Prone Hip Extension Muscle Recruitment is Associated with Hamstring Injury Risk in Amateur Soccer
Reference: Int J Sports Med. 2017 Jul 13. doi: 10.1055/s-0043-103016. [Epub ahead of print]
Authors: Schuermans J, Van Tiggelen D, Witvrouw E
Summary: 'Core stability' is considered essential in rehabilitation and prevention. Particularly with respect to hamstring injury prevention, assessment and training of lumbo-pelvic control is thought to be key. However, supporting scientific evidence is lacking. To explore the importance of proximal neuromuscular function with regard to hamstring injury susceptibility, this study investigated the association between the Prone Hip Extension (PHE) muscle activation pattern and hamstring injury incidence in amateur soccer players. 60 healthy male soccer players underwent a comprehensive clinical examination, comprising a range of motion assessments and the investigation of the posterior chain muscle activation pattern during PHE. Subsequently, hamstring injury incidence was recorded prospectively throughout a 1.5-season monitoring period. Players who were injured presented a PHE activation pattern that differed significantly from those who did not. Contrary to the controls, hamstring activity onset was significantly delayed (p=0.018), resulting in a shifted activation sequence. Players were 8 times more likely to get injured if the hamstring muscles were activated after the lumbar erector spinae instead of vice versa (p=0.009). Assessment of muscle recruitment during PHE demonstrated to be useful in injury prediction, suggesting that neuromuscular coordination in the posterior chain influences hamstring injury vulnerability.


#2 Effects of a Tapering Period on Physical Condition in Soccer Players
Reference: J Strength Cond Res. 2017 Jul 12. doi: 10.1519/JSC.0000000000002138. [Epub ahead of print]
Authors: Beltran-Valls MR, Camarero-Lopez G, Beltran-Garrido JV, Cecilia-Gallego P
Summary: The aim of this research was to analyze the effects of a two-week step tapering period on lower-limb muscle power, change of direction (COD) and acceleration capacities, and on the stress-recovery state in an amateur soccer team. Twenty-two male players were included in the study. Following a six-week progressive training, the sample was divided into: experimental group (n = 11), who did a two-week period of taper in which training volume was 50% reduced (intensity was kept high) and control group (n = 11), which kept on with the training. Muscle power (countermovement jump test), acceleration (10m sprint test), COD (Illinois test) and stress and recovery perceptions (RESTQ questionnaire) were evaluated before training, at the end of it (pre-tapering, PRE-TP) and after the tapering period (post-tapering, POST-TP). Following the taper, the experimental group in comparison to the control group showed significantly improved power (1029.71 ± 108.51 W/kg vs. 1084.21 ± 110.87 W/kg; p < 0.01), acceleration (1.72 ± 0.09 s vs. 1.67 ± 0.07 s; p < 0.05), and lower stress levels (1.9±0.5 vs. 1.6±0.5; p < 0.01) (PRE-TP vs. POST-TP, respectively). COD did not show significant changes. In conclusion, a two-week step tapering program was found to be an effective periodization strategy to increase muscle power and acceleration, and to reduce stress perception in soccer amateur players.


#3 Between-game variation of physical soccer performance measures in highly trained youth soccer players
Reference: J Strength Cond Res. 2017 Jul 12. doi: 10.1519/JSC.0000000000002132. [Epub ahead of print]
Authors: Doncaster G, Unnithan V
Summary: The purpose was to assess the between-game variation in measures of physical performance during 11 v 11 soccer match-play, over a short period of time, in highly trained youth soccer players. A single cohort observational study design was employed. Physical match performance data were collected from 17 male, highly trained youth soccer players (age: 13.3 ± 0.4 y) over three, 2 x 20min, 11 v 11 matches. Using 10 Hz GPS, the variables selected for analyses were total distance (TD), high-speed running (HSR), very high-speed running (VHSR), number of high-speed running efforts (HSReff) and number of very high-speed running efforts (VHSReff). Match data was also separated into cumulative 5 min epochs, to identify the peak 5 min epoch and the mean of the cumulative 5 min epochs for each match. Variability was quantified using the coefficient of variation (CV), Standard error of measurement (SEM) and intra-class correlation coefficient (ICC). Between- and within-player smallest worthwhile changes (SWC) were also calculated for each variable to aid in the interpretation of the data. Analysis of the variance between games reported a low CV for TD (3.8%) but larger CVs for HSR (33.3%), HSReff (35.4%) and VHSR and VHSReff (59.6 and 57.4 %, respectively). Analysis of 5 min epochs (peak and average) found an increase in the CVs beyond that of the values reported for the whole match. Between-player SWC in high intensity physical performance data ranged from 24.7 - 42.4 %, whereas within-player SWC ranged from 1.2 - 79.9%. The between-game variability of high and very high intensity activities in youth soccer players, across three soccer matches over a short period of time (2 weeks), is relatively 'large' and specific to the individual, thus highlighting the need for caution when interpreting physical performance data between games and players.


#4 Fatigue In U12 Soccer-7 Players During Repeated One-Day Tournament Games - A Pilot Study
Reference: J Strength Cond Res. 2017 Jul 12. doi: 10.1519/JSC.0000000000002141. [Epub ahead of print]
Authors: Sanchez-Sanchez J, Sanchez M, Hernandez D, Ramirez-Campillo R, Martinez C, Nakamura FY
Summary: The aim of this study was to describe and compare the distances and displacement speeds of U12 Soccer-7 athletes during four tournament Soccer-7 games (TG) played in less than 24-h (experimental condition) with those recorded during two league Soccer-7 games (LG) with 24-h of rest prior to the match (control condition). Ten participants (age = 10.3 ± 0.5 years) were recruited for the study. Main data analyzed during games included distance completed relative to match duration (Drel), maximal velocity and distance completed at different running speeds (including acceleration, deceleration, standing, walking, jogging, medium-intensity running, high-intensity running and sprinting). For data collection during games, athletes wore a GPS unit. Different (p<0.05) mean playing time was recorded during TG and LG (15.1 and 31.8 minutes/match, respectively). Drel during the four TG was maintained between 85.7 ± 8.5 m/min and 87.5 ± 8.5 m/min (P>0.05) and during the two LG between 84.2 ± 10.9 m/min and 87.5 ± 9.9 m/min (P>0.05). Moreover, similar Drel was recorded during TG and LG (86.8 m/min and 85.9 m/min, respectively). Compared to LG, during TG maximal velocity was lower (23.0 km/h and 21.3 km/h, respectively; P<0.05). In addition, compared to the last game of the tournament, in the preceding games the distance covered at low speeds (3.1-8.0 km/h) was lower (37.7% and 32.4%, respectively; P<0.05) and at high speeds (≥18.1 km/h) tend to be higher (2.5% and 3.3%, respectively). Therefore, compared with the control condition, accumulated Soccer-7 games with less than 24-h of inter-day rest negatively affects displacement speeds distribution (but not overall relative distances) in U12 Soccer-7 athletes. These results may help to better plan training and competition schedules to youth players.


#5 Effect of a professional soccer match in skin temperature of the lower limbs: a case study
Reference: J Exerc Rehabil. 2017 Jun 30;13(3):330-334. doi: 10.12965/jer.1734934.467. eCollection 2017 Jun.
Authors: de Andrade Fernandes A, Pimenta EM, Moreira DG, Sillero-Quintana M, Marins JCB, Morandi RF, Kanope T, Garcia ES
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5498090/pdf/jer-13-3-330.pdf
Summary: The purpose of this study is to analyze the relationship between lower limbs skin temperature (Tsk) recorded by infrared thermography and creatine kinase (CK) response following an official soccer game. A professional soccer player, from the first division Brazilian League, defender, 27 years and 183 cm of height was analyzed. Measures of Tsk with a thermal camera and blood CK concentrations were obtained 24 hr before (24H-PRE), 24 (24H-POST) and 48 hr (48H-POST) after an official match. The results showed that CK values were 193 U/L 24 hr before, rising to 1,083 U/L 24 hr after the game and 414 U/L 48 hr after the game. Anterior thigh Tsk was 31.5°C, 33.8°C, and 31.8°C in the moments 24H-PRE, 24H-POST, and 48H-POST, respectively. Similarly, anterior leg presented temperature of 31.2°C, 33.3°C, and 31.5°C at the same moments. Qualitative analysis of the thermograms showed that whole lower limbs are much warmer 24 hr after the match and certain areas as the right anterior thigh, the left anterior leg, both anterior ankles, and both posterior thighs have not fully recovered their initial Tsk 48 hr after the match. The results of this study indicate that participation in a professional soccer match can lead to significant increases in Tsk values measured by IRT 24 hr after the match. Considering this variable as an indicator of muscular damage, it could help in the process of training control, being part of an injury prevention program in professional soccer clubs.


#6 Quantifying changes in squat jump height across a season of men's collegiate soccer
Reference: J Strength Cond Res. 2017 Jul 8. doi: 10.1519/JSC.0000000000002118. [Epub ahead of print]
Authors: Sams ML, Sato K, DeWeese BH, Sayers AL, Stone MH
Summary: The purposes of this study were to examine the effectiveness of an athlete monitoring program in managing athlete neuromuscular fatigue across a men's collegiate soccer season as measured by changes in squat jump (SJ) height and to compare possible changes with session rating of perceived exertion (sRPE) training load (TL). Eighteen outfield Division I men's college soccer players performed SJ testing prior to each game of the fall season in addition to a baseline measurement at the start of pre-season. The athletes provided sRPE values after all training sessions, weight training, and games. Linear mixed modeling was used to compare changes in SJ height across the season with the baseline, and a correlation coefficient and single-lag cross-correlation coefficient were calculated between TL and changes in SJ height. No statistically significant decreases in SJ height occurred across the season, although a moderate practical decline occurred following the pre-season (-1.6 cm, ES = -0.70). The correlation between TL and changes in SJ height was statistically non-significant, while the cross-correlation was significant (r = 0.18, p = .48 and r = 0.55, p = 0.02, respectively). The athlete monitoring program was successful in managing the athletes' neuromuscular fatigue across the season as evidenced by the maintenance of SJ height and positive relationship between TL and changes in SJ height. Thus, SJ monitoring may serve as a useful fatigue monitoring tool for collegiate soccer athletes. Future study is needed relating changes in vertical jump performance to other markers of athlete preparedness and performance.


#7 Position specific acceleration and deceleration profiles in elite youth and senior soccer players
Reference: J Strength Cond Res. 2017 Apr 4. doi: 10.1519/JSC.0000000000001918. [Epub ahead of print]
Authors: Vigh-Larsen JF, Dalgas U, Andersen TB
Summary: The purpose of the study was to characterize and compare the position specific activity profiles of young and senior elite soccer players with special emphasis put on accelerations and decelerations. Eight professional senior matches were tracked using the ZXY tracking system and analyzed for number of accelerations and decelerations and running distances within different speed zones. Likewise, four U19- and five U17 matches were analyzed for comparison between youth and senior players. In senior players the total distance (TD) was 10776±107 m with 668±28 and 143±10 m being high-intensity running (HIR) and sprinting, respectively. Number of accelerations and decelerations were 81±2 and 84±3, with central defenders performing the lowest- and wide players the highest number. Declines were found between first and second halves for accelerations and decelerations (11±3 %), HIR (6±4 %) and TD (5±1 %), whereas sprinting distance did not differ. U19 players performed a higher number of accelerations, decelerations and TD compared to senior players. In conclusion, differences in number and distribution of accelerations and decelerations appeared between player positions, which is of importance when monitoring training and match loads and when prescribing specific training exercises. Further, youth players performed as much high-intensity activities as senior players indicating that this is not a discriminating physiological parameter between these players.


#8 Severe musculoskeletal time-loss injuries and symptoms of common mental disorders in professional soccer: a longitudinal analysis of 12-month follow-up data
Reference: Knee Surg Sports Traumatol Arthrosc. 2017 Jul 11. doi: 10.1007/s00167-017-4644-1. [Epub ahead of print]
Authors: Kiliç O, Aoki H, Goedhart E, Hagglund M, Kerkhoffs GMMJ, Kuijer PPFM, Walden M, Gouttebarge V
Summary: Psychological factors have shown to be predictors of injury in professional football. However, it seems that this is a two-way relationship, as severe musculoskeletal time-loss injuries have shown to be associated with the onset of symptoms of common mental disorders (CMD). There is no longitudinal study performed exploring this interaction between symptoms of CMD and injuries. The purpose of this study was to explore the interaction between severe musculoskeletal time-loss injuries and symptoms of CMD in professional football players over a 12-month period. Players were recruited by their national players' unions in five European countries. Symptoms of CMD included in the study were related to distress, anxiety/depression, sleep disturbance and adverse alcohol use. A total of 384 professional football players were enrolled in the study, of whom 262 (68%) completed the 12-month follow-up period. The mean age of the participants at baseline was 27 ± 5 years, and they had played professional football for 8 ± 5 years on average. Symptoms of CMD at baseline were not associated with the onset of severe musculoskeletal time-loss injuries during the follow-up period with relative risks (and 95% CI) ranging from 0.6 (0.3-1.0) to 1.0 (0.5-2.2). In contrast, severe musculoskeletal time-loss injuries reported at baseline were associated with the onset of symptoms of CMD during the follow-up period with relative risks ranging from 1.8 (0.8-3.7) to 6.9 (4.0-11.9). No relationship was found between symptoms of CMD and the onset of severe musculoskeletal time-loss injuries. However, professional football players who suffered from severe musculoskeletal time-loss injuries are likely to develop subsequent symptoms of CMD. This study emphasizes the need for an interdisciplinary medical approach, which not only focuses on the physical but also on the mental health of professional football players. An early identification of players at risk of symptoms of CMD, such as those suffering from severe musculoskeletal injuries, creates the opportunity for an interdisciplinary clinical medical team to treat the players timely and adequately.


#9 Individual ball possession in soccer
Reference: PLoS One. 2017 Jul 10;12(7):e0179953. doi: 10.1371/journal.pone.0179953. eCollection 2017.
Authors: Link D, Hoernig M
Download link: http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0179953&type=printable
Summary: This paper describes models for detecting individual and team ball possession in soccer based on position data. The types of ball possession are classified as Individual Ball Possession (IBC), Individual Ball Action (IBA), Individual Ball Control (IBC), Team Ball Possession (TBP), Team Ball Control (TBC) und Team Playmaking (TPM) according to different starting points and endpoints and the type of ball control involved. The machine learning approach used is able to determine how long the ball spends in the sphere of influence of a player based on the distance between the players and the ball together with their direction of motion, speed and the acceleration of the ball. The degree of ball control exhibited during this phase is classified based on the spatio-temporal configuration of the player controlling the ball, the ball itself and opposing players using a Bayesian network. The evaluation and application of this approach uses data from 60 matches in the German Bundesliga season of 2013/14, including 69,667 IBA intervals. The identification rate was F = .88 for IBA and F = .83 for IBP, and the classification rate for IBC was κ = .67. Match analysis showed the following mean values per match: TBP 56:04 ± 5:12 min, TPM 50:01 ± 7:05 min and TBC 17:49 ± 8:13 min. There were 836 ± 424 IBC intervals per match and their number was significantly reduced by -5.1% from the 1st to 2nd half. The analysis of ball possession at the player level indicates shortest accumulated IBC times for the central forwards (0:49 ± 0:43 min) and the longest for goalkeepers (1:38 ± 0:58 min), central defenders (1:38 ± 1:09 min) and central midfielders (1:27 ± 1:08 min). The results could improve performance analysis in soccer, help to detect match events automatically, and allow discernment of higher value tactical structures, which is based on individual ball possession.


#10 A shower before bedtime may improve the sleep onset latency of youth soccer players
Reference: Eur J Sport Sci. 2017 Jul 9:1-10. doi: 10.1080/17461391.2017.1346147. [Epub ahead of print]
Authors: Whitworth-Turner C, Di Michele R, Muir I, Gregson W, Drust B
Summary: During the competitive season, soccer players are likely exposed to numerous factors that may disrupt the process of sleep. The current investigation looked to evaluate a practical sleep hygiene strategy (10-min showering at ∼40°C before lights out), within a group of 11 youth soccer players in comparison to normal sleeping conditions (control). Each condition consisted of three days within a randomised crossover trial design. Sleep information was collected using a commercial wireless bedside sleep monitor. Measures of skin temperature were evaluated using iButton skin thermistors to establish both distal and proximal skin temperatures and distal to proximal gradient. The shower intervention elevated distal skin temperature by 1.1°C (95% CI: 0.1-2.1°C, p = .04) on average prior to lights out. The elevation in distal temperature was also present during the first 30-min following lights out (1.0°C, 95% CI: 0.4-1.6°C, p < .01). The distal to proximal gradient also showed a significant effect between the conditions within the first 30-min after lights out (0.7°C, 95% CI: 0.3-1.2°C, p < .01). On average the sleep latency of the youth soccer players was -7-min lower (95% CI: -13 to -2 min, p < .01) and sleep efficiency +2% higher (95% CI: 1-3%; p < .01) in the shower condition. These findings demonstrate that a warm shower performed before lights out may offer a practical strategy to promote thermoregulatory changes that may advance sleep onset latency and improve sleep efficiency in athletes.


#11 Dynamics of tactical behaviour in association football when manipulating players' space of interaction
Reference: PLoS One. 2017 Jul 14;12(7):e0180773. doi: 10.1371/journal.pone.0180773. eCollection 2017.
Authors: Ric A, Torrents C, Goncalves B, Torres-Ronda L, Sampaio J, Hristovski R
Download link: http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0180773&type=printable
Summary: The analysis of positional data in association football allows the spatial distribution of players during matches to be described in order to improve the understanding of tactical-related constraints on the behavioural dynamics of players. The aim of this study was to identify how players' spatial restrictions affected the exploratory tactical behaviour and constrained the perceptual-motor workspace of players in possession of the ball, as well as inter-player passing interactions. Nineteen professional outfield male players were divided into two teams of 10 and 9 players, respectively. The game was played under three spatial constraints: a) players were not allowed to move out of their allocated zones, except for the player in possession of the ball; b) players were allowed to move to an adjacent zone, and; c) non-specific spatial constraints. Positional data was captured using a 5 Hz interpolated GPS tracking system and used to define the configuration states of players for each second in time. The configuration state comprised 37 categories derived from tactical actions, distance from the nearest opponent, distance from the target and movement speed. Notational analysis of players in possession of the ball allowed the mean time of ball possession and the probabilities of passing the ball between players to be calculated. The results revealed that the players' long-term exploratory behaviour decreased and their short-term exploration increased when restricting their space of interaction. Relaxing players' positional constraints seemed to increase the speed of ball flow dynamics. Allowing players to move to an adjacent sub-area increased the probabilities of interaction with the full-back during play build-up. The instability of the coordinative state defined by being free from opponents when players had the ball possession was an invariant feature under all three task constraints. By allowing players to move to adjacent sub-areas, the coordinative state became highly unstable when the distance from the target decreased. Ball location relative to the scoring zone and interpersonal distance constitute key environmental information that constrains the players' coordinative behaviour. Based on our results, dynamic overlap is presented as a good option to capture tactical performance. Moreover, the selected collective (i.e. relational) variables would allow coaches to identify the effects of training drills on teams and players' behaviour. More research is needed considering these type variables to understand how the manipulation of constraints induce a more stable or flexible dynamical structure of tactical behaviour.


American Football
#1 Alcohol and violence in 2017 National Football League Super Bowl commercials
Reference: Health Promot Perspect. 2017 Jun 14;7(3):163-167. doi: 10.15171/hpp.2017.29. eCollection 2017.
Authors: MacLean SA, Basch CH, Garcia P
Download link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5497368/pdf/hpp-7-163.pdf
Summary: The National Football League (NFL) Super Bowl is a widely-viewed sports event and the commercials are especially popular among viewers. Previous research has demonstrated risky health behaviors in advertisements aired during sporting events. The purpose of this study was to analyze the content of the advertisements aired during the 2017 NFL Super Bowl. This cross-sectional study involved examining the content of all commercials, with an emphasis on health-compromising behaviors. The themes and highlights of the advertisements were analyzed based on whether there was a reference to alcohol or violence. A total of 103 unique commercials were analyzed. The most common themes were humor (n=43), happiness (n=25), innovation (n=25), and enjoyment or relaxation (n=25).Alcohol was referenced in 13 (12.6%, 95% CI 7.5%, 20.4%) of the commercials. Advertisements with alcohol references were more likely to contain the themes of partying (odds ratio [OR]:16.2, 95% CI 1.4-193.4, P=0.041) and enjoyment or relaxation (OR: 4.7, 95% CI 1.4-15.6,P=0.014). There were 24 commercials with references to violence and these were more likely tobe promoting a movie (OR: 5.4, 95% CI 3.5-8.2, P<0.001) or television program (OR: 8.9,95% CI 2.6-30.26, P<0.001). Parents should consider whether it is appropriate for their children to watch a concentrated number of intense images containing references to alcohol and violence during this popular sporting event.


Australian Football
#1 The influence of contextual factors on running performance in female Australian Football match-play
Reference: J Strength Cond Res. 2017 Jul 12. doi: 10.1519/JSC.0000000000002142. [Epub ahead of print]
Authors: Black GM, Gabbett TJ Naughton G, Cole MH, Johnston RD, Dawson B
Summary: Given the recent growth of the professional status among multiple female football codes, the aim of this study is to investigate the effects of contextual factors on activity profiles and pacing strategies in female Australian football players. Thirty-five female Australian football players participated in this study. Global positioning system analysis was completed over one competitive season. Matches were separated into eight 10-minute periods. Greater distances were covered during the first half irrespective of playing position (ES = 0.39-0.50, Likelihood ≥90%). Throughout a number of periods half-backs (defensive players) covered greater distances during losses (ES ≥0.74, Likelihood ≥92%) and against Top 3 opponents (ES ≥1.0, Likelihood ≥ 97%). Midfielders and half-backs covered greater distances (ES ≥ 0.49, Likelihood ≥89%) in the final match period in winning compared with losing matches. A reduction in player work-rate is evident during the second half of matches. The influence of contextual factors varied across positional groups. However, it is clear coaches could use player rotation both early in the match in an attempt to delay the effect of fatigue and more frequently during the second half to increase running intensity.


#2 Radio Gaga? Intra-team communication of Australian Rules Football Umpires - Effect of radio communication on content, structure and frequency
Reference: Ergonomics. 2017 Jul 12:1-43. doi: 10.1080/00140139.2017.1353140. [Epub ahead of print]
Authors: Neville TJ, Salmon PM, Read GJM
Summary: Intra-team communication plays an important role in team effectiveness in various domains including sport. As such, it is a key consideration when introducing new tools within systems that utilise teams. The difference in intra-team communication of Australian Rules Football (AFL) umpiring teams was studied when umpiring with or without radio communications technology. A cross-sectional observational study was conducted to analyse the verbal communication of seven umpiring teams (20 participants) grouped according to their experience with radio communication. The results identified that radio communication technology increased the frequency and altered the structure of intra-team communication. Examination of the content of the intra-team communication identified impacts on the 'Big Five' teamwork behaviours and associated coordinating mechanisms. Analysis revealed that the communications utilised did not align with the closed-loop form of communication described in the Big Five model. Implications for teamwork models, coaching and training of AFL umpires are discussed.  Practitioner statement Assessing the impact of technology on performance is of interest to ergonomics practitioners. The impact of radio communications on teamwork is explored in the highly dynamic domain of AFL umpiring. When given radio technology, intra-team communication increased which supported teamwork behaviours such as backup behaviour and mutual performance monitoring.

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