Latest research in football - week 37 - 2015

As previous literature updates, we have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases.

Following studies were retrieved for this week:


#1 Evaluation of longitudinal steroid profiles from male football players in UEFA competitions between 2008 and 2013
Reference: Drug Test Anal. 2015 Sep 3. doi: 10.1002/dta.1851. [Epub ahead of print]
Authors: Baume N, Geyer H, Vouillamoz M, Grisdale R, Earl M, Aguilera R, Cowan DA, Ericsson M, Gmeiner G, Kwiatkowska D, Kioukia-Fougia N, Molina A, Ruivo J, Segura J, Van Eenoo P, Jan N, Robinson N, Saugy M
Summary: Testosterone and related compounds are the most recurrent doping substances. The steroid profile, consisting of the quantification of testosterone and its metabolites, has been described as the most significant biomarker to detect doping with pseudo-endogenous anabolic steroids. The steroidal module of the Athlete Biological Passport (ABP) was launched by the World Anti-Doping Agency (WADA) in 2014. To assess the value of introducing the module to its anti-doping programme, the Union of European Football Associations (UEFA) decided to analyze retrospectively the steroid profile data of 4195 urine samples, collected from 879 male football players and analyzed in 12 WADA-accredited laboratories between 2008 and mid-2013. This study focused on the evaluation of T/E ratios. The coefficient of variation (CV) and the adaptive model were the two statistical models used to study the longitudinal follow-up. A CV of 46% was determined to be the maximal natural intra-individual variation of the T/E when the sequence consisted of single data points analyzed in different laboratories. The adaptive model showed some profiles with an atypical T/E sequence and also enabled an estimate of the prevalence of external factors impacting the T/E sequences. Despite the limitations of this retrospective study, it clearly showed that the longitudinal and individual follow-up of the T/E biomarker of the players is a good tool for target testing in football. UEFA has therefore decided to implement the steroidal module of the ABP from the start of the next European football season in September 2015

#2 Unknown unknowns and lessons from non-operative rehabilitation and return to play of a complete anterior cruciate ligament injury in English Premier League football
Reference: Br J Sports Med doi:10.1136/bjsports-2015-095141
Authors: Weiler, R. Editorial
Summary: An English Premier League (EPL) footballer decides to open-mindedly try, at least initially, non-operative and non-interventional treatment of a complete anterior cruciate ligament (ACL) rupture. At 5 weeks, he feels great and fully trusts his knee, sailing with confidence through every graded progression in his evolving rehabilitation programme. He continues with rehabilitation to full training within 8 weeks of a complete ACL injury.1 Now, almost 24 months later, he is still training and playing full competitive professional football. During 22 months available for team selection, there have been no episodes of instability, no knee pain, no effusions, no soft tissue injuries and no discernible impairment on function. There was no change on clinical ligament tests either. Treatment was entirely non-surgical with no use of needles for aspiration or injection. He remains aware that he is very lucky so far, that he cannot predict what could happen in future, possibly requiring surgery, and he is aware that risk of osteoarthritis is high following ACL injury whether reconstruction has taken place or not.2–4 Before jumping to conclusions, perhaps it is worth reading the full paper at BMJ Case Reports to decide for yourself what you may have done in this situation

#3 Efficacy of the FIFA 11+ Injury Prevention Program in the Collegiate Male Soccer Player
Reference: Am J Sports Med. 2015 Sep 16. pii: 0363546515602009. [Epub ahead of print]
Authors: Silvers-Granelli H, Mandelbaum B, Adeniji O, Insler S, Bizzini M, Pohlig R, Junge A, Snyder-Mackler L, Dvorak J
Summary: The Fédération Internationale de Football Association (FIFA) 11+ program has been shown to be an effective injury prevention program in the female soccer cohort, but there is a paucity of research to demonstrate its efficacy in the male population. The purpose was to examine the efficacy of the FIFA 11+ program in men's collegiate United States National Collegiate Athletic Association (NCAA) Division I and Division II soccer. Before the commencement of the fall 2012 season, every NCAA Division I and Division II men's collegiate soccer team (N = 396) was solicited to participate in this research study. Human ethics review board approval was obtained through Quorum Review IRB. Sixty-five teams were randomized: 34 to the control group (CG; 850 players) and 31 to the intervention group (IG; 675 players). Four teams in the IG did not complete the study, reducing the number for analysis to 61. The FIFA 11+ injury prevention program served as the intervention and was utilized weekly. Athlete-exposures (AEs), compliance, and injury data were recorded using a secure Internet-based system. In the CG, 665 injuries (mean ± SD, 19.56 ± 11.01) were reported for 34 teams, which corresponded to an incidence rate (IR) of 15.04 injuries per 1000 AEs. In the IG, 285 injuries (mean ± SD, 10.56 ± 3.64) were reported for 27 teams, which corresponded to an IR of 8.09 injuries per 1000 AEs. Total days missed because of injury were significantly higher for the CG (mean ± SD, 13.20 ± 26.6 days) than for the IG (mean ± SD, 10.08 ± 14.68 days) (P = .007). There was no difference for time loss due to injury based on field type (P = .341). The FIFA 11+ significantly reduced injury rates by 46.1% and decreased time loss to injury by 28.6% in the competitive male collegiate soccer player (rate ratio, 0.54 [95% CI, 0.49-0.59]; P < .0001) (number needed to treat = 2.64).

#4 Prevalence of dental trauma and mouthguard awareness among weekend warrior soccer players
Reference: J Oral Sci. 2015;57(3):191-4. doi: 10.2334/josnusd.57.191.
Authors: Dursun E, D Ilarslan Y, Ozgul O, Donmez G
Summary: Traumatic dental and facial injuries are frequent in sports and often cause esthetic, functional, psychological, and economic problems. The term "weekend warrior" is used to describe people who participate in physically demanding activities only on the weekend, or part-time. In this prospective cohort study, we examined the prevalence of dental trauma and knowledge of traumatic dental injuries among weekend warriors in Ankara, Turkey. A detailed questionnaire on mouthguard awareness and knowledge and experience of dental trauma was distributed to 1,007 weekend warrior athletes participating in a soccer tournament. The results showed that 9.8% of participants had experienced orofacial trauma, 21.7% were aware of mouthguards, 2.9% reported using mouthguards, 15.4% were aware of the field of sports dentistry, and 19.6% were aware of emergency treatment for dental trauma. Participation in sports, especially contact sports, greatly increases the risk of dental injury. The present results show that knowledge of traumatic orofacial and dental injuries is limited among weekend warriors. Public health authorities should develop relevant educational programs, including broad dissemination of information on the risks of traumatic dental injuries and methods for protection against such injuries. (J Oral Sci 57, 191-194, 2015).

#5 Physical and anthropometric changes during pre and in-season in professional soccer players
Reference: J Sports Med Phys Fitness. 2015 Sep 10. [Epub ahead of print]
Authors: Fessi MS, Zarrouk N, Filetti C, Rebai H, Elloumi M, Moalla W.
Summary: The purpose of this study was to examine the changes in anthropometric and physical fitness characteristics in professional soccer players at the beginning of the season, after pre- season camp and during in-season. 17 players were evaluated on 3 different periods (June: T0, August: T1 and December: T2). Each evaluation consisted of anthropometric measurements (body mass, height, and body fat) and physical fitness tests (counter movement jump (CMJ), counter movement jump with arm (CMJA), 10-m sprint, 30-m sprint and maximal aerobic speed (MAS)). Comparatively with T0, all physical performances achieved in T1 were significantly improved (MAS: p<0.01, 10-m sprint: p<0.05, 30-m sprint: p<0.05, CMJ: p<0.01, and CMJA: p<0.05). The decrease in training load during in-season is associated by significant decrement in MAS (p<0.05) and preserved performances in 10 (p=0.85) and 30-m sprint (p=0.99), CMJ (p=0.34) and CMJA (p=0.87) completed in T2 comparatively with T1. Physical fitness performances achieved in T2 remain higher than that obtained in T0 (MAS: p<0.01, 10-m sprint: p<0.01, 30-m sprint: p<0.05 and CMJ: p<0.05) and remain similar for CMJA (p=0.13). No significant changes were observed in anthropometric measurements throughout the study. The main finding of this study was that a greater training load accomplished during pre-season could lead to an improvement in the physical fitness during in-season in professional soccer players. We suggest that this higher training load meets the needed required for the professional soccer although the training loads are declined during in-season.

#6 Muscle damage, inflammatory, immune and performance responses to three football games in 1 week in competitive male players
Reference: Eur J Appl Physiol. 2015 Sep 16. [Epub ahead of print]
Authors: Mohr M, Draganidis D, Chatzinikolaou A, Barbero-Álvarez JC, Castagna C, Douroudos I, Avloniti A, Margeli A, Papassotiriou I, Flouris AD, Jamurtas AZ, Krustrup P, Fatouros IG
Summary: We examined effects of a three-game, 1-week microcycle (G1, G2, G3) on recovery of performance and inflammatory responses in professional male footballers. Players were randomized into an experimental (EXP; N = 20) and a control group (CON; N = 20). Blood was drawn and repeated sprint ability (RSA), muscle soreness and knee range of motion (KJRM) were determined pre- and post-games and during recovery. High-intensity running during G2 was 7-14 % less compared to G1 and G3. RSA declined in EXP by 2-9 % 3 days post-game with G2 causing the greatest performance impairment. In EXP, game play increased muscle soreness (~sevenfold) compared to CON with G2 inducing the greatest rise, while KJRM was attenuated post-game in EXP compared to CON (5-7 %) and recovered slower post G2 and G3 than G1. CK, CRP, sVCAM-1, sP-Selectin and cortisol peaked 48 h post-games with G2 eliciting the greatest increase. Leukocyte count, testosterone, IL-1β and IL6 responses, although altered 24 h post each game, were comparable among games. Plasma TBARS and protein carbonyls rose by ~50 % post-games with G2 eliciting the greatest increase 48 h of recovery. Reduced to oxidized glutathione ratio declined for 24 h post all games with G2 displaying the slowest recovery. Total antioxidant capacity and glutathione peroxidase activity increased (9-56 %) for 48 h in response to game play. In summary, post-game performance recovery and inflammatory adaptations in response to a three-game weekly microcycle displayed a different response pattern, with strong indications of a largest physiological stress and fatigue after the middle game that was preceded by only a 3-day recovery.

#7 Injuries in male professional football: A prospective comparison between individual and team-based exposure registration
Reference: Scand J Med Sci Sports. 2015 Sep 17. doi: 10.1111/sms.12551. [Epub ahead of print]
Authors: Kristenson K, Bjørneboe J, Waldén M, Andersen TE, Ekstrand J, Hägglund M
Summary: Methodological considerations of football injury epidemiology have only scarcely been described. The aim of this study was to evaluate the inter-rater agreement in injury capture rate and injury categorization for data registered in two different prospective injury surveillance audits studying the same two Norwegian male professional football clubs for two consecutive seasons, 2008-2009. One audit used team-based exposure (TBE) recording and the other individual-based exposure (IBE). The number of injuries recorded and corresponding injury rates (injuries/1000 h exposure) were compared between audits. Cohen's kappa and prevalence-adjusted bias-adjusted kappa (PABAK) coefficients were calculated for injury variables. Of 323 injuries included, the IBE audit captured 318 (overall capture rate 98.5%, training 98.9%, match 97.8%) and the TBE audit 303 injuries (overall capture rate 93.8%, training 91.4%, match 97.1%). Agreement analysis showed kappa and PABAK coefficients regarded as almost perfect (> 0.81) for 8 of 9 injury variables, and substantial (ƙ 0.75) for the variable injury severity. In conclusion, the capture rate for training injuries was slightly higher with IBE recording, and inter-agreement in injury categorization was very high.

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