Latest research in football - week 16 - 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 Football injuries during the 2014 FIFA World Cup
Reference:  Br J Sports Med. 2015 May;49(9):599-602. doi: 10.1136/bjsports-2014-094469.
Authors: Junge A, Dvořák J
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Summary: FIFA has surveyed match injuries in its tournaments since 1998. The purpose of this study was to analyse the incidence and characteristics of match injuries incurred during the 2014 FIFA World Cup in comparison to previous FIFA World Cups. The chief physicians of the participating teams reported all newly incurred injuries of their players after the match on a standardised report form. 124 (97%) forms were returned. A total of 104 injuries were reported, equivalent to an incidence of 1.68 injuries per match (95% CI 1.36 to 2.00). 64 (63.4%) injuries were caused by contact with another player. Thigh (26; 25%) and head (19; 18%) were the most frequently injured body parts. The most frequent diagnosis was thigh strain (n=18). Five concussions and three fractures to the head were reported. While most thigh strains (15/17; 88.2%) occurred without contact, almost all head injuries (18/19; 94.7%) were caused by contact. 0.97 injuries per match (95% CI 0.72 to 1.22) were expected to result in absence from training or match. Eight injuries were classified as severe. The incidence of match injuries in the 2014 FIFA World Cup was significantly lower than the average of the four preceding FIFA World Cups, both for all injuries (2.34; 95% CI 2.15 to 2.53) and time-loss injuries (1.51; 95% CI 1.37 to 1.65). The overall incidence of injury during the FIFA World Cups decreased from 2002 to 2014 by 37%. A detailed analysis of the injury mechanism is recommended to further improve prevention strategies.
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#2 F-MARC: promoting the prevention and management of sudden cardiac arrest in football
Reference: Br J Sports Med. 2015 May;49(9):597-8. doi: 10.1136/bjsports-2015-094764.
Authors: Kramer EB, Dvorak J, Schmied C, Meyer T
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Summary: Sudden cardiac death is the most common cause of unnatural death in football. To prevent and urgently manage sudden cardiac arrest on the football field-of-play, F-MARC (FIFA Medical and Research Centre) has been fully committed to a programme of research, education, standardisation and practical implementation. This strategy has detected football players at medical risk during mandatory precompetition medical assessments. Additionally, FIFA has (1) sponsored internationally accepted guidelines for the interpretation of an athlete's ECG, (2) developed field-of-play-specific protocols for the recognition, response, resuscitation and removal of a football player having sudden cardiac arrest and (3) introduced and distributed the FIFA medical emergency bag which has already resulted in the successful resuscitation of a football player who had a sudden cardiac arrest on the field-of-play. Recently FIFA, in association with the Institute of Sports and Preventive Medicine in Saarbrücken, Germany, established a worldwide Sudden Death Registry with a view to documenting fatal events on the football field-of-play. These activities by F-MARC are testimony to FIFA's continued commitment to minimising sudden cardiac arrest while playing football.

#3 Cartilage issues in football-today's problems and tomorrow's solutions
Reference: Br J Sports Med. 2015 May;49(9):590-596. doi: 10.1136/bjsports-2015-094772.
Authors: Mithoefer K, Peterson L, Zenobi-Wong M, Mandelbaum BR
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Summary: Articular cartilage injury is prevalent in football players and results from chronic joint stress or acute traumatic injuries. Articular cartilage injury can often result in progressive painful impairment of joint function and limit sports participation. Management of articular cartilage injury in athletes aims to return the player to competition, and requires effective and durable joint surface restoration that resembles normal hyaline articular cartilage that can withstand the high joint stresses of football. Existing articular cartilage repair techniques can return the athlete with articular cartilage injury to high-impact sports, but treatment does not produce normal articular cartilage, and this limits the success rate and durability of current cartilage repair in athletes. Novel scientific concepts and treatment techniques that apply modern tissue engineering technologies promise further advancement in the treatment of these challenging injuries in the high demand athletic population. We review the current knowledge of cartilage injury pathophysiology, epidemiology and aetiology, and outline existing management algorithms, developing treatment options and future strategies to manage articular cartilage injuries in football players.

#4 High prevalence of medication use in professional football tournaments including the World Cups between 2002 and 2014: a narrative review with a focus on NSAIDs
Reference: Br J Sports Med. 2015 May;49(9):580-2. doi: 10.1136/bjsports-2015-094784.
Authors: Tscholl PM, Vaso M, Weber A, Dvorak J
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Summary: The use of medication in international football has been monitored since the 2002 FIFA World Cup. Team physicians were asked to provide information on prescribed medication 72 h prior to each match for every player. 69% of adult male players reported using medication, with more than half the players using non-steroidal anti-inflammatory drugs (NSAIDs). Up to one-third of all players used NSAIDs prior to every match, regardless of whether they took the field or not. The mean intake of medication was significantly higher during the FIFA Women's World Cup (0.85 vs 0.77 substances per player and per match in men, p<0.001), whereas the use of NSAIDs was similar to that for men. In the Under-20 and Under-17 male competitions, the use of medication was lower as 60% of players used some kind of medication and 43% of the players used NSAIDs during the tournaments. Despite the potential side effects of medication, especially of NSAIDs in the recovery process after a sports activity, there is no evidence of decreasing intake. The reported incidence is alarming, and moreover is most probably underestimated, since self-medication by the players or treatment already prescribed by club physicians is not included in the published reports. Future studies should focus on the daily dosage, time of treatment and especially the medical indication for painkilling agents to better understand the underlying factors.

#5 FIFA 11+: an effective programme to prevent football injuries in various player groups worldwide-a narrative review
Reference: Br J Sports Med. 2015 May;49(9):577-9. doi: 10.1136/bjsports-2015-094765.
Authors: Bizzini M, Dvorak J
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Summary: In 2009, FIFA promoted and disseminated the FIFA 11+ injury prevention programme worldwide. Developed and studied by the FIFA Medical Assessment and Research Centre (F-MARC), the programme was based on a randomised controlled study and one countrywide campaign in amateur football that significantly reduced injuries and healthcare costs. Since the FIFA 11+ launch, key publications have confirmed the preventive effects of the programme and have evaluated its performance effects in female as well as male amateur football players. Furthermore, implementation strategies of this prevention programme have also been studied. The goal of this narrative review was to summarise the available scientific evidence about the FIFA 11+ programme. While FIFA continues to disseminate and implement FIFA 11+ among its Member Associations, adaptations of the injury prevention programme for children and referees have been developed and are currently being evaluated.

#6 Recreational football for disease prevention and treatment in untrained men: a narrative review examining cardiovascular health, lipid profile, body composition, muscle strength and functional capacity
Reference: Br J Sports Med. 2015 May;49(9):568-76. doi: 10.1136/bjsports-2015-094781.
Authors: Bangsbo J, Hansen PR, Dvorak J, Krustrup P
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Summary: Over the past 10 years, researchers have studied the effects of recreational football training as a health-promoting activity for participants across the lifespan. This has important public health implications as over 400 million people play football annually. Results from the first randomised controlled trial, published in the BJSM in January 2009, showed that football increased maximal oxygen uptake and muscle and bone mass, and lowered fat percentage and blood pressure, in untrained men, and since then more than 70 articles about football for health have been published, including publications in two supplements of the Scandinavian Journal of Medicine and Science in Sports in 2010 and 2014, prior to the FIFA World Cup tournaments in South Africa and Brazil. While studies of football training effects have also been performed in women and children, this article reviews the current evidence linking recreational football training with favourable effects in the prevention and treatment of disease in adult men.

#7 Twenty years of the FIFA Medical Assessment and Research Centre: from 'Medicine for Football' to 'Football for Health'
Reference: Br J Sports Med. 2015 May;49(9):561-3. doi: 10.1136/bjsports-2015-094805.
Authors: Dvorak J, Junge A
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#8 Joint-position sense is altered by football pre-participation warm-up exercise and match induced fatigue
Reference: Knee. 2015 Apr 8. pii: S0968-0160(14)00233-6. doi: 10.1016/j.knee.2014.10.002. [Epub ahead of print]
Authors: Salgado E, Ribeiro F, Oliveira J
Summary: The demands to which football players are exposed during the match may augment the risk of injury by decreasing the sense of joint position. This study aimed to assess the effect of pre-participation warm-up and fatigue induced by an official football match on the knee-joint-position sense of football players. Fourteen semi-professional male football players (mean age: 25.9±4.6years old) volunteered in this study. The main outcome measures were rate of perceived exertion and knee-joint-position sense assessed at rest, immediately after a standard warm-up (duration 25min), and immediately after a competitive football match (90minutes duration). Perceived exertion increased significantly from rest to the other assessments (rest: 8.6±2.0; after warm-up: 12.1±2.1; after football match: 18.5±1.3; p<0.001). Compared to rest, absolute angular error decreased significantly after the warm-up (4.1°±2.2° vs. 2.0°±1.0°; p=0.0045). After the match, absolute angular error (8.7°±3.8°) increased significantly comparatively to both rest (p=0.001) and the end of warm-up (p<0.001). Relative error showed directional bias with an underestimation of the target position, which was higher after the football match compared to both rest (p<0.001) and after warm-up (p<0.001). The results indicate that knee-joint-position sense acuity was increased by pre-participation warm-up exercise and was decreased by football match-induced fatigue. Warm-up exercises could contribute to knee injury prevention, whereas the deleterious effect of match-induced fatigue on the sensorimotor system could ultimately contribute to knee instability and injury.

#9 Injury prevention strategies at the FIFA 2014 World Cup: perceptions and practices of the physicians from the 32 participating national teams
Reference: Br J Sports Med 2015;49:603-608 doi:10.1136/bjsports-2015-094747
Authors: McCall A, Davison M, Andersen TE, Beasley I, Bizzini M, Dupont G, Duffield R, Carling C, Dvorak J7
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Summary: The available scientific research regarding injury prevention practices in international football is sparse. The purpose of this study was to quantify current practice with regard to (1) injury prevention of top-level footballers competing in an international tournament, and (2) determine the main challenges and issues faced by practitioners in these national teams. A survey was administered to physicians of the 32 competing national teams at the FIFA 2014 World Cup. The survey included 4 sections regarding perceptions and practices concerning non-contact injuries: (1) risk factors, (2) screening tests and monitoring tools, (3) preventative strategies and (4) reflection on their experience at the World Cup.  Following responses from all teams (100%), the present study revealed the most important intrinsic (previous injury, accumulated fatigue, agonist:antagonist muscle imbalance) and extrinsic (reduced recovery time, training load prior to and during World Cup, congested fixtures) risk factors during the FIFA 2014 World Cup. The 5 most commonly used tests for risk factors were: flexibility, fitness, joint mobility, balance and strength; monitoring tools commonly used were: medical screen, minutes/matches played, subjective and objective wellness, heart rate and biochemical markers. The 5 most important preventative exercises were: flexibility, core, combined contractions, balance and eccentric.  The present study showed that many of the National football (soccer) teams’ injury prevention perceptions and practices follow a coherent approach. There remains, however, a lack of consistent research findings to support some of these perceptions and practices.

#10 Three distinct mechanisms predominate in non-contact anterior cruciate ligament injuries in male professional football players: a systematic video analysis of 39 cases
Reference: Br J Sports Med. 2015 Apr 23. pii: bjsports-2014-094573. doi: 10.1136/bjsports-2014-094573. [Epub ahead of print]
Authors: Waldén M, Krosshaug T, Bjørneboe J, Andersen TE, Faul O, Hägglund M
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Summary: Current knowledge on anterior cruciate ligament (ACL) injury mechanisms in male football players is limited. The purpose of the study was to describe ACL injury mechanisms in male professional football players using systematic video analysis. We assessed videos from 39 complete ACL tears recorded via prospective professional football injury surveillance between 2001 and 2011. Five analysts independently reviewed all videos to estimate the time of initial foot contact with the ground and the time of ACL tear. We then analysed all videos according to a structured format describing the injury circumstances and lower limb joint biomechanics. Twenty-five injuries were non-contact, eight indirect contact and six direct contact injuries. We identified three main categories of non-contact and indirect contact injury situations: (1) pressing (n=11), (2) re-gaining balance after kicking (n=5) and (3) landing after heading (n=5). The fourth main injury situation was direct contact with the injured leg or knee (n=6). Knee valgus was frequently seen in the main categories of non-contact and indirect contact playing situations (n=11), but a dynamic valgus collapse was infrequent (n=3). This was in contrast to the tackling-induced direct contact situations where a knee valgus collapse occurred in all cases (n=3). Eighty-five per cent of the ACL injuries in male professional football players resulted from non-contact or indirect contact mechanisms. The most common playing situation leading to injury was pressing followed by kicking and heading. Knee valgus was frequently seen regardless of the playing situation, but a dynamic valgus collapse was rare.

#11 Direct and indirect measurement of neuromuscular fatigue in Canadian football players
Reference: Appl Physiol Nutr Metab. 2015 Jan 16:1-10. [Epub ahead of print]
Authors: Clarke N, Farthing JP, Lanovaz JL, Krentz JR.
Summary: This study assessed the effects of a fatiguing game simulation (G-Sim) on the balance of collegiate Canadian football players. The purpose of the study was to evaluate postural control as a potential tool for monitoring neuromuscular fatigue (NMF) in collision-based team sports. Fifteen male Canadian football players were recruited (mean ± SD: age 21.8 ± 1.6 years, weight 97.6 ± 14.7 kg). Indirect NMF measures (postural sway and countermovement jump (CMJ)) were performed 24 h before (TBase), immediately before (TPre) and after (TPost), and 24 h (T24) and 48 h after (T48) a Canadian football G-Sim. Peak isometric knee extensor torque of a maximal voluntary contraction (MVC) and electrically evoked tetani at 20 Hz (P20) and 80 Hz (P80) were also recorded as direct NMF measures at TBase, TPre, TPost, and T48. At TPost, we observed significant declines in MVC, P20, and the MVC/P80 ratio (-15.3%, -15.7%, and -12.1%, respectively; n = 12) along with reductions in CMJ takeoff velocity and peak power (-6.9% and -6.5%, respectively; n = 12) and larger area of the center of pressure trajectory (95.2%; n = 10) during a 60-s postural sway task. All variables were no longer different than baseline by T48. Acute neuromuscular impairment in this cohort is likely attributable to alterations in excitation-contraction coupling due to structural damage and central activation failure. Congruency between the direct and indirect measures of NMF suggests monitoring postural sway has the potential to identify both neuromuscular and somatosensory alterations induced by acute game-induced fatigue in collision-based team sports players.

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