Latest research in football - week 34 - 2017

#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.