Latest research in football - week 49 - 2021

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 Maturity-Associated Differences in Match Running Performance in Elite Male Youth Soccer Players

Reference: Int J Sports Physiol Perform. 2021 Oct 27;1-9.  doi: 10.1123/ijspp.2020-0950. Online ahead of print.

Authors: James Parr, Keith Winwood, Emma Hodson-Tole, Frederik J A Deconinck, James P Hill, Sean P Cumming

Summary: The aim was to investigate the influence of maturation on match running performance in elite male youth soccer players. A total of 37 elite male youth soccer participants from an English professional soccer academy from the U14s, U15s, and U16s age groups were assessed over the course of 1 competitive playing season (2018-2019). Relative biological maturity was assessed using percentage of predicted adult height. A global positioning system device was used between 2 and 30 (mean = 8 [5]) times on each outfield player. The position of each player in each game was defined as defender, midfielder, or attacker and spine or lateral. A total of 5 match-running metrics were collected total distance covered, high-speed running distance, very high-speed running distance, maximum speed attained, and number of accelerations. Relative biological maturity was positively associated with all global positioning system running metrics for U14s. The U15/16s showed variation in the associations among the global positioning system running metrics against maturity status. A multilevel model which allowed slopes to vary was the best model for all parameters for both age groups. In the U14 age group, advanced maturation was associated with greater high-speed running distance. However, maturation did not contribute toward variance in any of the indices of running performance in the U15/16s. In the U15/16 age group, significance was observed in the spine/lateral playing positions when undertaking actions that required covering distance at high speeds. Maturation appeared to have an impact on match-running metrics within the U14s cohort. However, within the U15/16s, the influence of maturation on match-running metrics appeared to have less of an impact.



#2 Arthroscopic resection as a rapid recovery treatment for Os acetabuli in soccer players who had undergone hip arthroscopy: a case series with 1-year follow-up

Reference: Arch Orthop Trauma Surg. 2021 Oct 26. doi: 10.1007/s00402-021-04229-9. Online ahead of print.

Authors: Jorge Salvador, Roberto Seijas, Alfred Ferré-Aniorte, Patricia Laiz, David Barastegui, Ramón Cugat

Summary: Os acetabuli (OSA) is defined as a radiopaque structure located around the acetabular rim highly related to Femoroacetabular Impingement (FAI). Its treatment depends on the perspective of post-surgical joint instability. Ossicle resection is recommended if the femoral head is covered enough by the labrum. Previous research has described the results of this technique in general population. The aim of this study is to describe the outcomes and the time and rate of return to play (RTP) after hip arthroscopy and OSA removal in soccer players. This study is a retrospective analysis of a prospective database containing all the consecutive soccer players who had undergone hip arthroscopy between 2018 and 2019. The subjects diagnosed with OSA and a center-edge angle (CEA) > 25 ° were included in the analysis. All the patients were treated with arthroscopic removal of the OSA and femoral osteoplasty. Hip function was assessed using the Modified Harris Hip Score (MHHS) before and at 3 and 12 months after surgery. Rate of RTP and competitive level at RTP were assessed at a 1-year follow-up. Between 2018 and 2019, 90 soccer players were treated with hip arthroscopy in our facilities. Six of them (6.6%) were diagnosed with OSA. Mean (SD) MHHS values were 69.7 (12.1) before the surgery, 89.7 (6.7) at 3 months post-surgery and 95.7 (5.1) at 12 months post-surgery. All the subjects reported significant improvements in their MHHS scores at 3 and 12 months post-surgery compared with pre-surgery levels (p < 0.01). Non-significant differences were found between 3 and 12 months post-surgery (p > 0.05). All the subjects (100%) returned to previous competitive levels. After surgery, all the soccer players returned to previous competitive level. Preoperative MHHS improved significantly at 3 months maintained for up to 12 months.



#3 Tensiomyographic Responses to Warm-Up Protocols in Collegiate Male Soccer Athletes

Reference: J Funct Morphol Kinesiol. 2021 Sep 23;6(4):80. doi: 10.3390/jfmk6040080.

Authors: Michael J Redd, Tristan M Starling-Smith, Chad H Herring, Matt S Stock, Adam J Wells, Jeffrey R Stout, David H Fukuda

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Summary: The mechanical properties of knee flexors and extensors in 15 collegiate male soccer players following different warm-up protocols [small-sided games (SSG), dynamic (DYN), and plyometric (PLY)] were evaluated. Tensiomyography (TMG) was used to assess contraction time (Tc), delay time (Td) and maximal displacement (Dm) of the rectus femoris (RF) and biceps femoris (BF) of both legs before and after each warm-up, while countermovement jump height variables, 20 m sprint, t-test and sit-and-reach were measured following the warm-ups. TMG was analyzed using a three-way [condition × time × leg] ANOVA, while performance variables were analyzed with a repeated measures ANOVA. Main effects of time were observed for BF-Tc (p = 0.035), RF-Td (p < 0.001), and BF-Td, (p = 0.008), and a main effect of condition was seen for RF-Tc (p = 0.038). Moreover, participants' 20 m sprint improved following SSG (p = 0.021) compared to DYN and PLY. Sit-and-reach was greater following PLY (p = 0.021). No significant interactions were noted for the measured TMG variables. Warm-up-specific improvements were demonstrated in sprint speed and flexibility following SSG and PLY, respectively. The present study revealed changes in certain TMG measures following the warm-ups that suggest enhanced response of lower leg muscles regardless of specific activities used.



#4 The Influence of Time Winning and Time Losing on Position-Specific Match Physical Demands in the Top One Spanish Soccer League

Reference: Sensors (Basel). 2021 Oct 14;21(20):6843.doi: 10.3390/s21206843.

Authors: José C Ponce-Bordón, Jesús Díaz-García, Miguel A López-Gajardo, David Lobo-Triviño, Roberto López Del Campo, Ricardo Resta, Tomás García-Calvo

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Summary: The aim of the present study was to analyze the influence of time winning and time losing on position-specific match physical demands with and without ball possession in the top Spanish professional soccer league. All matches played in the First Spanish soccer league over four consecutive seasons (from 2015/16 to 2018/19) were recorded using an optical tracking system (i.e., ChyronHego), and the data were analyzed via Mediacoach®. Total distance (TD), and TD > 21 km·h-1 covered with and without ball possession were analyzed using a Linear Mixed Model, taking into account the contextual variables time winning and losing. Results showed that TD and TD > 21 km·h-1 covered by central midfielders (0.01 and 0.005 m/min, respectively), wide midfielders (0.02 and 0.01 m/min, respectively), and forwards (0.03 and 0.02 m/min, respectively) significantly increased while winning (p < 0.05). By contrast, TD and TD > 21 km·h-1 covered by central defenders (0.01 and 0.008 m/min, respectively) and wide defenders (0.06 and 0.008 m/min, respectively) significantly increased while losing (p < 0.05). In addition, for each minute that teams were winning, total distance with ball possession (TDWP) decreased, while, for each minute that teams were losing, TDWP increased. Instead, TDWP > 21 km·h-1 obtained opposite results. Total distance without ball possession increased when teams were winning, and decreased when teams were losing. Therefore, the evolution of scoreline significantly influences tactical-technical and physical demands on soccer matches.



#5 Single and Serial Carbohydrate Mouth Rinsing Do Not Improve Yo-Yo Intermittent Recovery Test Performance in Soccer Players

Reference: Int J Sport Nutr Exerc Metab. 2021 Oct 22;1-8. doi: 10.1123/ijsnem.2021-0174. Online ahead of print.

Authors: Rafaela Nehme, Flávia M S de Branco, Públio F Vieira, Ana Vitória C Guimarães, Gederson K Gomes, Gabriela P Teixeira, Pedro H Rodrigues, Leonardo M de Castro Junior, Guilherme M Puga, Bryan Saunders, Erick P de Oliveira

Summary: Carbohydrate (CHO) mouth rinsing seems to improve performance in exercises lasting 30-60 min. However, its effects on intermittent exercise are unclear. It is also unknown whether serial CHO mouth rinses can promote additional ergogenic effects when compared with a single mouth rinse. The aim of this study was to evaluate the effect of single and serial CHO mouth rinses on Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR1) performance in soccer players. In a randomized, crossover, double-blind, placebo-controlled design, 12 male (18.9 ± 0.5 years) soccer players performed eight serial mouth rinses under three different conditions: placebo solution only (noncaloric juice), seven placebo mouth rinses plus a single CHO mouth rinse (8% maltodextrin), or eight CHO mouth rinses (8-CHO). Following the final mouth rinse, individuals performed the Yo-Yo IR1 test to evaluate the maximal aerobic endurance performance measured via total distance covered. There were no differences in Yo-Yo IR1 performance between sessions (p = .32; single CHO mouth rinse (8% maltodextrin): 1,198 ± 289 m, eight CHO mouth rinses: 1,256 ± 253 m, placebo: 1,086 ± 284 m). In conclusion, single and serial CHO mouth rinsing did not improve performance during the Yo-Yo IR1 for soccer players. These data suggest that CHO mouth rinsing is not an effective ergogenic strategy for intermittent exercise performance irrespective of the number of rinses.



#6 How Do the Habitual Sleep Patterns of Elite Female Basketball and Soccer Athletes Compare With the General Population?

Reference: Int J Sports Physiol Perform. 2021 Oct 22;1-7. doi: 10.1123/ijspp.2021-0189. Online ahead of print.

Authors: Kathleen H Miles, Brad Clark, Jocelyn K Mara, Peter M Fowler, Joanna Miller, Kate L Pumpa

Summary: The purpose was to compare the habitual sleep of female basketball and soccer athletes to age- and sex-matched controls and to characterize the sleep of basketball and soccer athletes at different competition locations and on the days surrounding competition. Using an observational case-control design, 41 female participants were recruited to participate, consisting of 11 basketball athletes (mean [SD]: age = 24.1 [4.9] y), 10 soccer athletes (24.8 [6.4] y), and 20 nonathletic controls (24.2 [2.8] y). Sleep was monitored using actigraphy for four 7-day periods throughout the preseason and subsequent competition season. Generalized linear models were used to analyze the effect of group and competition situation (eg, Home or Away) on sleep. During habitual conditions, basketball athletes had longer sleep durations (7.4 [1.5] h) than soccer athletes (7.0 [1.2] h, P < .001) and controls (7.3 [1.2] h, P = .002). During competition, basketball and soccer athletes had longer sleep durations following home (7.7 [1.7] and 7.2 ± 1.3 h) compared with away games (6.8 [1.8] and 7.0 [1.3] h). In addition, basketballers went to bed earlier (23:49 [01:25]) and woke earlier (07:22 [01:59]) following away games compared with soccer athletes (00:10 [01:45] and 08:13 [01:45]). Basketballers had longer habitual sleep durations compared with soccer athletes and nonathletic controls. During competition, basketballers had earlier bed and wake times compared with soccer athletes following away games, highlighting the need for individualized sleep strategies.



#7 Relative Training Load and Match Outcome: Are Professional Soccer Players Actually Undertrained during the In-Season?

Reference: Sports (Basel). 2021 Oct 8;9(10):139. doi: 10.3390/sports9100139.

Authors: Toni Modric, Mario Jelicic, Damir Sekulic

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Summary: Previous studies examined training/match ratios (TMr) to determine the training load relative to the match load, but the influence of the relative training load (RTL) on success in soccer is still unknown. Therefore, this study aimed to investigate the possible influence of RTL on final match outcome in soccer (win, draw, and loss). Running performances (RP) of soccer players (n = 21) in the Croatian highest national soccer competition were analyzed during the season 2020-2021. Data were measured by the global positioning system in 14 official matches and 67 training sessions. RTL was assessed by TMr, which were calculated as the ratio of RP during training and match in the same week, evaluating the following measures: TDr (total distance ratio), LIDr (low-intensity distance ratio), RDr (running distance ratio), HIDr (high-intensity distance ratio), ACCr (total accelerations ratio), DECr (total decelerations ratio), HI-ACCr (high-intensity accelerations ratio), HI-DECr (high-intensity decelerations ratio). All TMr were examined separately for each training session within in-season microcycles (categorized as days before the match day, i.e., MD minus). Spearman correlations were used to identify association between match outcome and TMr. The results indicated negative associations between match outcome and TDr, LIDr, ACCr and DECr on MD-1 and MD-2). In contrast, positive associations were evidenced between match outcome, and HIDr on MD-3 and TDr, LIDr, ACCr and DECr on MD-5 (p < 0.05; all moderate correlations). These findings demonstrate that final match outcome in soccer was associated with greater RTL of (i) high-intensity running three days before the match, (ii) total and low-intensity running, accelerations and decelerations five days before the match, and (iii) lower RTL of total and low-intensity running, accelerations and decelerations one and two days before the match.



#8 Four Weeks of Power Optimized Sprint Training Improves Sprint Performance in Adolescent Soccer Players

Reference: Int J Sports Physiol Perform. 2021 Oct 27;1-9. doi: 10.1123/ijspp.2020-0959. Online ahead of print.

Authors: Mikael Derakhti, Domen Bremec, Tim Kambič, Lasse Ten Siethoff, Niklas Psilander

Summary: This study compared the effects of heavy resisted sprint training (RST) versus unresisted sprint training (UST) on sprint performance among adolescent soccer players. Twenty-four male soccer players (age: 15.7 [0.5] y; body height: 175.7 [9.4] cm; body mass: 62.5 [9.2] kg) were randomly assigned to the RST group (n = 8), the UST group (n = 10), or the control group (n = 6). The UST group performed 8 × 20 m unresisted sprints twice weekly for 4 weeks, whereas the RST group performed 5 × 20-m heavy resisted sprints with a resistance set to maximize the horizontal power output. The control group performed only ordinary soccer training and match play. Magnitude-based decision and linear regression were used to analyze the data. The RST group improved sprint performances with moderate to large effect sizes (0.76-1.41) across all distances, both within and between groups (>92% beneficial effect likelihood). Conversely, there were no clear improvements in the UST and control groups. The RST evoked the largest improvements over short distances (6%-8%) and was strongly associated with increased maximum horizontal force capacities (r = .9). Players with a preintervention deficit in force capacity appeared to benefit the most from RST. Four weeks of heavy RST led to superior improvements in short-sprint performance compared with UST among adolescent soccer players. Heavy RST, using a load individually selected to maximize horizontal power, is therefore highly recommended as a method to improve sprint acceleration in youth athletes.



#9 Injury rates and patterns in French male professional soccer clubs: a comparison between a regular season and a season in the Covid-19 pandemic

Reference: Res Sports Med. 2021 Oct 27;1-11. doi: 10.1080/15438627.2021.1989434. Online ahead of print.

Authors: Emmanuel Orhant, Jean-François Chapellier, Christopher Carling

Summary: This study investigated time-loss injury occurrence and patterns between the first season (2020/21, S2) completed during the Covid-19 pandemic (longer pre-season following cancellation of the 2019/20 season but shorter duration) and a regular season (2018/19, S1) in French Ligue 1 and 2 professional soccer clubs. Epidemiological data were prospectively recorded in a national injury database by each club's physician. In all clubs combined, the mean number of injuries per club was 31.5 and 36.6 in S2 and S1, respectively (-13.9%). Overall match injury incidence (per 1000 hours) in all clubs combined was lower in S2 versus S1 (22.23 vs 25.96, p < 0.01). In Ligue 1 clubs alone, match-play incidences for injury overall (24.92 vs 29.42), muscle strains (10.59 vs 13.24) and strains specifically in the hamstring region (4.52 vs 6.22) were lower in S2 versus S1 (all p < 0.05). No differences in the incidence of match injuries affecting the ankle and knee regions were observed. Changes in the 2020/21 season structure and duration owing to the Covid-19 pandemic seem not to have had a negative effect on injury occurrence and patterns in French professional soccer clubs.



#10 The influence of season phase on multivariate load relationships in professional youth soccer

Reference: J Sports Sci. 2021 Oct 27;1-6. doi: 10.1080/02640414.2021.1993642. Online ahead of print.

Authors: Patrick C Maughan, Niall G MacFarlane, Paul A Swinton

Summary: The purpose of this research was to assess relationships between subjective and external measures of training load in professional youth footballers, whilst accounting for the effect of the stage of the season. Data for ratings of perceived exertion (RPE) and seven global positioning systems (GPS) derived measures were collected from 20 players (age = 17.4 ± 1.3 yrs, height = 178.0 ± 8.1 cm, mass = 71.8 ± 7.2 kg) across a 47-week season. The season was categorised by a pre-season phase, and two competitive phases (Comp1, Comp2). The structure of the data were investigated using principal component analysis. An extraction criterion of component with eigenvalues ≥1.0 was used. Two components were retained for the pre-season period explaining a cumulative variance of 77.1%. Single components were retained for both Comp1 and Comp2 explaining 73.3% and 74.3% of variance, respectively. Identification of single components may suggest that measures are related and can be used interchangeably, however these interpretations should be considered with caution. The identification of multiple components in the pre-season phase suggests that univariate measures may not be sufficient when considering load experienced. These results suggest that factoring load based on measures of volume and intensity should be considered.



#11 Relationship Between Explosive Strength Capacity of the Knee Muscles and Deceleration Performance in Female Professional Soccer Players

Reference: Front Physiol. 2021 Oct 11;12:723041. doi: 10.3389/fphys.2021.723041. eCollection 2021.

Authors: Qingshan Zhang, Aurélie Léam, Alexandre Fouré, Del P Wong, Christophe A Hautier

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Summary: The present study aimed to investigate the relationship between linear deceleration performance and explosive strength capacity of the knee muscles. Fourteen female professional soccer players completed the maximal sprint deceleration tests and knee flexor (KF) and knee extensor (KE) isokinetic concentric (240° and 60°.s-1) and eccentric contractions (30°.s-1). Linear deceleration performance was evaluated from horizontal breaking force (F H), power (P H), and impulse (I H) during a maximal linear deceleration. The peak torque (PT) of KF and KE, PT ratio between KF and KE (conventional and functional H/Q ratio), rate of torque development (RTD) for each muscle group, and RTD between KF and KE (RTD H/Q) were extracted from the isokinetic contractions. Pearson's correlation coefficients revealed that the eccentric (30°.s-1) and concentric (60°.s-1, 240°.s-1) KE peak torque, and the concentric KF peak torque (240°.s-1) were significantly correlated with FH, PH , and IH (-0.75<r<-0.54). Moreover, a significant correlation was found between KE RTD during eccentric contraction and FH , PH , and IH (-0.63<r<-0.54). Besides, a significant correlation was observed between RTD H/Q at 60°.s-1 and PH , IH (-0.61<r<-0.57). No significant relationship was observed between the H/Q ratio, KF RTD and deceleration performance. These main findings indicated the importance of the ability to quickly produce high KE eccentric torque, contributing to braking force production. Meanwhile, RTD H/Q should be assessed for its essential role in knee joint dynamic stability and can be a relevant index to determine deceleration performance.



#12 Acromioclavicular Joint Separation in UEFA Soccer Players: A Matched-Cohort Analysis of Return to Play and Player Performance From 1999 to 2018

Reference: Orthop J Sports Med. 2021 Oct 21;9(10):23259671211026262.  doi: 10.1177/23259671211026262. eCollection 2021 Oct.

Authors: Connor C Diaz, Enrico M Forlenza, Ophelie Z Lavoie-Gagne, Derrick M Knapik, Avinaash Korrapati, Jorge Chahla, Brian Forsythe

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Summary: Acromioclavicular joint (ACJ) separation injuries are uncommon in professional soccer players, threatening future performance and team contributions. Data regarding return to play (RTP) in professional soccer players after ACJ separation are limited. The purose was to determine the rate, time to RTP, and player performance after ACJ separation in soccer players from the top 5 professional European leagues when compared with a retrospective, matched cohort of uninjured players. Professional soccer players suffering ACJ separation injuries between 1999 and 2018 were identified and were matched to uninjured players (2 controls to 1 injured player) by position, height, age, season year, and length of time played. Information on date of injury, timing to RTP, and player performance metrics (minutes played, games played, goals scored, assists made, and points per game) were collected from,,, official team websites, public injury reports, and press releases. Change in performance metrics for the 4 seasons after the season of injury were based on metrics 1 season before injury. Univariate comparisons were performed using independent 2-group t tests and Wilcoxon rank-sum tests when normality of distributions was violated. A total 59 soccer players with ACJ separation injuries were identified. Mean age at injury was 24.6 ± 5.3 years. Of these, 81% of the players returned to play, with 69% returning within postinjury season 1. Mean time to RTP was 49.8 ± 24.3 days (5.9 ± 4.1 games). Two players suffered recurrent ACJ separation injuries in their professional soccer careers. There were no significant differences between athletes who sustained ACJ injuries versus control athletes in the number of games played, minutes per game per season, goals scored, assists, or points in the 4 seasons after injury. Defenders played fewer minutes and recorded fewer assists during postinjury season 1 when compared with control athletes. Of the 59 elite soccer players who sustained ACJ separation injuries during the study period, 81% returned to elite competition. Performance metrics were similar to preinjury levels and matched, uninjured control players.



#13 Seasonal Changes and Relationships in Training Loads, Neuromuscular Performance, and Recovery and Stress State in Competitive Female Soccer Players

Reference: Front Sports Act Living. 2021 Oct 11;3:757253. doi: 10.3389/fspor.2021.757253. eCollection 2021.

Authors: Ai Ishida, Caleb D Bazyler, Adam L Sayers, Michael H Stone, Jeremy A Gentles

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Summary: The purpose of this study was to examine seasonal changes in training load (TL), neuromuscular performance, subjective recovery, and stress state, and to investigate the relationships between acute and chronic TL and neuromuscular performance in competitive female soccer players. Nine competitive female soccer players (20.0 ± 1.7 years; 60.3 ± 6.3 kg; 164.0 ± 5.8 cm) completed the Short Recovery and Stress Scale and the countermovement jump (CMJ) with polyvinyl chloride pipe (CMJ0) and 20 kg barbell (CMJ20) at 2-3 h before 1st match (NC1), 6th match (NC2), 9th match (C1), and 15th match (C2) of the competitive season. TL included total distance, high-speed running, and PlayerLoad. Acute and chronic TL was calculated by using the average of 2 days (D2), 7 days (D7), and 21 days (D21) prior to four different match play. Significant decreases were found from NC1 to C1 in D7 total distance [p = 0.03, Cohen's effect size (dz) = 1.40]. D7 total distance and PlayerLoad significantly decreased from NC to C1 and C2 (p = 0.001-0.01, dz = 1.40-1.72). Significant increases were observed from NC1 to C1 in CMJ0 jump height (p = 0.03, dz = 1.40), (p = 0.021, dz = 1.44), and peak power (p = 0.03, dz = 1.32). Significant negative correlations were observed for D7 total distance and CMJ0 jump height (p = 0.02, r = 0.79) and peak power (p = 0.03, r = 0.71) at C2, while significant positive correlations were observed at C1 for D7 PlayerLoad and CMJ0 jump height (p = 0.02, r = 0.80).  Polyvinyl chloride pipe (CMJ0) jump height and peak power may increase from preseason to the midcompetitive season. Seasonal variations may affect the relationships between D7 TL and CMJ0 performance.



#14 Cognitive ability in former professional football (soccer) players is associated with estimated heading frequency

Reference: J Neuropsychol. 2021 Oct 28. doi: 10.1111/jnp.12264. Online ahead of print.

Authors: Davide Bruno, Andrew Rutherford

Summary: The link between football (soccer) headings and dementia risk is a concern given the popularity of this sport worldwide. To assess this link, the cognitive ability of former professional players was tested and self-reported estimates on heading frequency were collected. A survey was co-designed with former players to gather demographics data; information on playing career, including playing position; estimates of total head injuries sustained in training and match play; and estimates of heading frequency during training and match play. Data then were collected by post from 60 males (mean age = 67.5; SD = 9.5), who had played professionally for teams in England. In addition to the survey, each individual also completed the Test Your Memory (TYM) self-administered cognitive test to evaluate overall ability. Bayesian and traditional linear regression analyses were carried out using the TYM score as outcome. Predictors were estimated career head injuries and estimated career headers, while we controlled for age and reported non-football head injuries. The results of our analyses showed that estimated career headers, but not estimated career head injuries, predicted TYM scores. To our knowledge, this is the first study to provide direct evidence supporting a link between heading the ball and cognitive impairment in retired professional football players.



#15 Does motor coordination influence perceptual-cognitive and physical factors of agility in young soccer players in a sport-specific agility task?

Reference: Sports Biomech. 2021 Oct 28;1-14. doi: 10.1080/14763141.2021.1995476. Online ahead of print.

Authors: Glauber B Menezes, Ricardo S Oliveira, Ayrton B M Ferreira, Tereza V L Assis, Elias S Batista, Jon L Oliver, Rhodri S Lloyd, Arnaldo L Mortatti

Summary: This study aims to determine whether motor coordination influences the perception-decision time (perceptual-cognitive factor) and movement response time (physical factor) of young soccer players in a sport-specific agility task regardless of maturation. Eighty-seven young male soccer players were analysed. Anthropometric measurements were used to determine the maturity offset, while physical qualities including agility, change of direction speed (CODS) and motor coordination were also assessed. The following variables were obtained from these tests: Motor coordination score, perception-decision time, movement response time, agility time and CODS time. Motor coordination revealed a non-significant correlation with perception-decision time (r = 0.10, p = 0.34). However, motor coordination showed negative and significant correlations with CODS time (r = -0.47, p < 0.01), agility time (r = -0.52, p < 0.01) and movement response time (r = -0.62, p < 0.01). In addition, regression analysis showed that each increase in motor coordination score was associated with significant decreases in agility time (b = -0.023), movement response time (b = -0.021) and CODS time (b = -0.021) independent of maturity offset. The results of this study indicated that motor coordination was significantly related to the physical factors of agility in young soccer players.



#16 A qualitative exploration of the use of player loans to supplement the talent development process of professional footballers in the under 23 age group of English football academies

Reference: J Sports Sci. 2021 Oct 27;1-9. doi: 10.1080/02640414.2021.1996985. Online ahead of print.

Authors: Gareth Prendergast, Luke Gibson

Summary: A range of literature has contributed to talent development and career transition in professional football. Recently, attention has shifted to the under 23s age group of English football academies, highlighting limitations in the efficacy of this age group in developing professional footballers. Such limitations have led to players going on loan to football clubs in lower divisions to supplement their development; however, we have yet to develop a scholarly understanding of this approach. Therefore, the aim of this study was to investigate the role of an under 23s player loan in developing professional footballers. Using a qualitative design, data were collected through the use of semi-structured interviews with nine participants. Following a process of thematic analysis, findings highlighted the potential of a loan in contributing to a player's physical and psycho-social development. Positive performances whilst on loan were also perceived to be contributing factors in increased first team selection opportunities at the player's parent club. However, an emphasis was also placed on the need to provide consistent pastoral support to under 23s players during their loan period. Finally, more longitudinal methodologies are required to understand the individual and temporal nature of positive and negative loan experiences of under 23s players.



#17 Epidemiology of injuries in male and female youth football players: A systematic review and meta-analysis

Reference: J Sport Health Sci. 2021 Oct 23;S2095-2546(21)00109-5. doi: 10.1016/j.jshs.2021.10.002. 

Authors: Francisco Javier Robles-Palazón, Alejandro López-Valenciano, Mark De Ste Croix, Jon L Oliver, Alberto García-Gómez, Pilar Sainz de Baranda, Francisco Ayala

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Summary: The purpose was to conduct a systematic review and meta-analysis of epidemiological data of injuries in male and female youth football players. Searches were performed in MEDLINE/PubMed, Web of Science, Cochrane Library, and SPORTDiscus databases. Studies were considered if they reported injury incidence rate among male and female youth (≤19 years old) football players. Two reviewers (FJRP and ALV) extracted data and assessed trial quality using the STROBE statement and Newcastle Ottawa Scale. The Grading of Recommendations Assessment, Development, and Evaluation approach determined the quality of evidence. Studies were combined using a Poisson random effects regression model. Forty-three studies were included. The overall incidence rate was 5.70 injuries/1000 h in males and 6.77 injuries/1000h in females. Match injury incidence (14.43 injuries/1000 h in males and 14.97 injuries/1000 h in females) was significantly higher than training injury incidence (2.77 injuries/1000h in males and 2.62 injuries/1000 h in females). The lower extremity had the highest incidence rate in both sexes. The most common type of injury was muscle/tendon for males and joint/ligament for females. Minimal injuries were the most common in both sexes. The incidence rate of injuries increased with advances in chronological age in males. Elite male players presented higher match injury incidence than sub-elite. In females, there was a paucity of data for comparison across age groups and levels of play. The high injury incidence rates and sex differences identified for the most common location and type of injury reinforce the need for implementing different targeted injury risk mitigation strategies in male and female youth football players.



#18 Epidemiology of Football-Related Sudden Cardiac Death in Turkey

Reference: Medicina (Kaunas). 2021 Oct 14;57(10):1105. doi: 10.3390/medicina57101105.

Authors: Ali Işın, Adnan Turgut, Amy E Peden

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Summary: Sudden cardiac death (SCD), particular among elite footballers, has attracted much attention in recent times. However, limited information exists on football-related SCD in Turkey. Autopsy-based studies of sports-related sudden deaths in Turkey are rare and often have small sample sizes. To address this, this study aimed to determine the population-based incidence and profile of football-related SCD nationally in Turkey.  Due to a lack of national data on this issue, football-related SCD (non-elite competitive or recreational football) between 1 January 2011, and 31 December 2019 were identified by dual, independent identification and screening of online media reports. Deaths were explored by sex, age group, season, and phase of exercise. Descriptive statistics were utilised. Age-specific mortality rates and proportional mortality rates were calculated.  In total, 118 football-related SCD were identified, a crude mortality rate of 0.41 per 100,000 population. All fatalities were males and the mean age was 35.5 years ± 10.4. Those aged 40-49 years recorded the highest mortality rate (0.67/100,000), three times the risk of those aged 50-59 years (RR = 3.1; 95%CI:1.5-6.4). Those aged 30-39 recorded the highest age-specific proportional mortality rate (0.86/1000 deaths). The highest risk occurred while playing football (n = 97; 82.2%), with another 15% of deaths (n = 18) occurring within 1 h of play. Almost all fatalities (n = 113; 95.8%) occurred during participation in recreational football.  This study has identified football-related SCD most commonly occurs during recreational football among males aged 30-49 years. It is recommended males of this age participating in recreational football be encouraged to seek pre-participation heart health checks. Given the value of automated external defibrillators (AEDs) in responding to out-of-hospital cardiac arrest, future research should explore the feasibility and effectiveness of AEDs in preventing football-related SCD in Turkey including training of first responders in cardiopulmonary resuscitation and AED use.



#19 Functional and Anthropometrical Screening Test among High Performance Female Football Players: A Descriptive Study with Injury Incidence Analysis, the Basque Female Football Cohort (BFFC) Study

Reference: Int J Environ Res Public Health. 2021 Oct 12;18(20):10658. doi: 10.3390/ijerph182010658.

Authors: Marta Álvarez-Zafra, Javier Yanci, Ibai García-Tabar, Eder Bikandi, Saioa Etxaleku, Mikel Izquierdo, Tron Krosshaug, Uxue Fernandez-Lasa, Igor Setuain

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Summary: The main objectives of the present study were to describe the injury incidence and to analyze the anthropometric and physical characteristics of players from three high-level women's football teams. The present study involved 54 female football players (21.9 ± 4.9 years old) from three different teams competing in the Spanish Reto Iberdrola-Segunda División PRO league. A battery of tests was carried out to determine the anthropometric and physical performance characteristics of the players along with an injury incidence record during a full competitive season. The obtained results showed that there was a high incidence of injury, as 38% of the players suffered some type of injury during the season (range 1-5; 1.75 ± 1.02 injuries per player). Injuries occurred in both matches and during training at a similar percentage (48.6 vs. 51.4%), and the majority of the registered episodes were graded as moderate or severe injury types (60%). Players suffering from an injury accumulated a total of 1587 chronological days off work due to injury during the season, with a recurrence rate of 55%. Considering the high incidence of injury, and the injury burden and the reinjure rate observed in this research, it seems necessary to apply the most efficient prevention and recovery measures possible in these female football teams. These descriptive data could serve athletic trainers and medical staff of female football teams to better understand their own screening procedure-derived data.



#20 Depressive Symptoms and Burnout in Football Players: A Systematic Review

Reference: Brain Sci. 2021 Oct 14;11(10):1351. doi: 10.3390/brainsci11101351.

Authors: Hugo Sarmento, Roberta Frontini, Adilson Marques, Miguel Peralta, Nestor Ordoñez-Saavedra, João Pedro Duarte, António Figueiredo, Maria João Campos, Filipe Manuel Clemente


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Summary: The purpose of this article was to systematically review and organise the available literature devoted to the topic of depressive symptoms and burnout in football players. A systematic search was conducted in Web of Science, Scopus, SPORTdiscus, PubMed, and Psychinfo for articles published up to June 2020. The searches yielded 1589 articles, and after the screening process, a total of 18 studies met the eligibility criteria and were included for review. Playing position and conflicts with coach/management seems to have a direct influence on the prevalence of depressive symptoms in current players as do the injuries and life events of former players. During the pre-competition phase, most of the athletes displayed reduced rates, indicating burnout. An exploration of the mental health of football players will help to create models of care and guide professionals so that they may help players achieve better performance while also having better wellbeing. Understanding how to prevent and cope with the emotional wellbeing of football players will be possible to guide players and coaches.



#21 The COVID-19 Pandemic Impact on Away and Home Victories in Soccer and Rugby Union

Reference: Front Sports Act Living. 2021 Oct 18;3:695922. doi: 10.3389/fspor.2021.695922. eCollection 2021.

Authors: Adrien Sedeaud, Quentin De Larochelambert, Julien Schipman, Jean-Francois Toussaint

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Summary: The aim was to measure the impact of restrictions due to COVID on the proportion of matches won at home, away and draw in professional soccer and rugby union. Two samples of professional soccer and rugby union matches were collected from 2012-13 to 2020-21 seasons. For soccer, data involved first and second division matches of the England, Spain, Germany, Italy, France, Belgium, Scotland, Greece, Portugal, and Turkey championships. For rugby union, championships concerned are Premiership Rugby, Celtic League, Top 14, and Pro D2. The proportions of home, away wins and draw were calculated and compared. A chi-square test of independence between years and types of result was realized to identify an overall inhomogeneity. The proportion of away matches won between the 2012-13 and 2020-21 seasons increased significantly from 28.5 ± 1.2% to 32.5 ± 1.5% in soccer and from 38.0 ± 3.6% to 42.8 ± 5.0% in rugby union. In Premiership Rugby championship, the victory percentage at home dropped from 55.8 ± 3.1% when tifosi were present to 45.8 ± 12.8% when they were not. The home advantage was drastically reduced in empty stadiums for several European soccer and rugby union professional championships. It vanished in the Premiership Rugby and Celtic League during the 2020-21 season.



#22 Differences on Prosaccade Task in Skilled and Less Skilled Female Adolescent Soccer Players

Reference: Front Psychol. 2021 Oct 14;12:711420. doi: 10.3389/fpsyg.2021.711420. eCollection 2021.

Author: Junyi Zhou

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Summary: Although the relationship between cognitive processes and saccadic eye movements has been outlined, the relationship between specific cognitive processes underlying saccadic eye movements and skill level of soccer players remains unclear. Present study used the prosaccade task as a tool to investigate the difference in saccadic eye movements in skilled and less skilled Chinese female adolescent soccer players. Fifty-six healthy female adolescent soccer players (range: 14-18years, mean age: 16.5years) from Fujian Youth Football Training Base (Fujian Province, China) took part in the experiment. In the prosaccade task, participants were instructed to fixate at the cross at the center of the screen as long as the target appeared peripherally. They were told to saccade to the target as quickly and accurately as possible once it appeared. The results indicated that skilled soccer players exhibited shorter saccade latency (p=0.031), decreased variability of saccade latency (p=0.013), and higher spatial accuracy of saccade (p=0.032) than their less skilled counterparts. The shorter saccade latency and decreased variability of saccade latency may imply that the attentional system of skilled soccer player is superior which leads to smaller attention fluctuation and less attentional lapse. Additionally, higher spatial accuracy of saccade may imply potential structural differences in brain underlying saccadic eye movement between skilled and less skilled soccer players. More importantly, the results of the present study demonstrated that soccer players' cognitive capacities vary as a function of their skill levels. The limitations of the present study and future directions of research were discussed.



#23 Effectiveness of a Walking Football Program for Middle-Aged and Older Men With Type 2 Diabetes: Protocol for a Randomized Controlled Trial

Reference: JMIR Res Protoc. 2021 Nov 3;10(11):e28554. doi: 10.2196/28554.

Authors: Ana Barbosa, João Brito, Pedro Figueiredo, André Seabra, Romeu Mendes

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Summary: Studies on walking football have found positive effects on health; however, there are still several research gaps when applying walking football programs for patients with type 2 diabetes. This study aims to test the effectiveness of a walking football exercise program on glycemic control and cardiovascular risk factors in middle-aged and older men with type 2 diabetes. The study will be run as a randomized controlled trial with a 6-month duration in Portugal. Eligible participants will be randomized using a 1:1 ratio for intervention or control groups and compared using an intention-to-treat analysis. The intervention will consist of a walking football exercise program. The control group will continue with usual care in primary health care units. The primary outcome will be the mean difference in glycated hemoglobin between intervention and control groups after 6 months. Secondary outcomes include the mean differences in fasting blood glucose, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, systolic and diastolic blood pressure, body mass index, waist circumference, fat-free mass, and fat mass. Additionally, secondary outcomes include the incidence of exercise-related injuries and adverse events and the walking football exercise program's cost-utility. The study protocol is being prepared to be submitted to the Health Ethics Committee of the Northern Regional Health Administration, Portugal. After approval, participant recruitment will start in primary health care units in Porto's metropolitan area by family medicine doctors. Walking football might have the potential to be effective in improving glycemic control and cardiovascular risk factors, with a low rate of exercise-related injuries and adverse events and a good cost-utility ratio. Therefore, walking football may be a sustainable intervention strategy for type 2 diabetes management.



#24 Injuries in elite-level women's football-a two-year prospective study in the Irish Women's National League

Reference: Scand J Med Sci Sports. 2021 Oct 31. doi: 10.1111/sms.14062. Online ahead of print.

Authors: Dan Horan, Catherine Blake, Martin Hägglund, Seamus Kelly, Mark Roe, Eamonn Delahunt

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Summary: We investigated the pattern of injuries in elite-level women's football in Ireland, during a two-season prospective injury surveillance study in the Women's National League (WNL). Seven out of the eight clubs (271 players) in the WNL were followed prospectively during the 2018 and 2019 seasons. The injury incidence rate in matches (19.2/1000 h) was 7.5 times higher than in training (2.5/1000 h). Players, on average, sustained 0.69 injuries per season (266 injuries/383 player seasons), which equates to 15 time-loss injuries per season for a squad of 22 players. The majority of the injuries sustained by players were lower extremity injuries (85%), of which, 46% had a non-contact injury mechanism. Muscle, ligament, and contusion injuries were the most common injury types, while the ankle, knee, and thigh were the most commonly injured body sites. The most common injuries sustained over the two seasons were lateral ankle sprains (13.9%), hamstring strains (12.4%), knee meniscus/cartilage injuries (7.5%), adductor strains (6%), quadriceps strains (4.5%), and ankle contusions (4.5%). The injuries with the highest injury burden were ACL injuries (59 days lost/1000 h), knee meniscus/cartilage injuries (23/1000 h), lateral ankle sprains (21/1000 h), hamstring strains (12/1000 h), MCL sprains (11/1000 h), and quadriceps strains (11/1000 h). There were 8 ACL tears documented over the 2 seasons, which accounted for 28% of all time lost to injury with a mean days lost per injury of 247. We recommend that clubs in the WNL in Ireland should implement injury risk mitigation strategies, with a particular focus on injuries with a high injury burden.



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