Original paperFactors associated with increased propensity for hamstring injury in English Premier League soccer players
Introduction
Over the past two decades, injury trends in elite-level soccer have changed1, 2 with the hamstring muscle group now recognised as the most frequently injured structure, accounting for more time lost than any other muscle group.3, 4 Indeed, the initial Football Association Audit of Injuries5 found that over a period of two seasons, hamstring strains were the most prevalent injury, accounting for 12% of all injuries in the English Premier League. Additionally, injuries to the hamstring muscles have been shown to have the highest rates of recurrence5, 6, 7 with premature return to play7 and inadequate or inappropriate rehabilitation programs8 suggested as contributing factors. Logically, injuries sustained by key players competing in elite team sports may result in a negative impact on team performance, success and inevitably, financial well being. Consequently, a fuller understanding of the mechanisms of hamstring injury and players most at risk will be of great benefit to those working in professional sport.
The relationship between the architecture of the hamstring muscle group, its contribution to human locomotion, and its propensity for injury is undeniably complex. Despite the fact that it is widely thought that in many instances the cause of hamstring injury may be multifactorial,9 to our knowledge nearly all studies to date have modelled predictor variables in isolation.1, 10 Discussion of the contribution of proposed pre-disposing factors to hamstring injury is beyond the scope of this article, but has been extensively reviewed in previous literature.7, 11 To date, few investigators have attempted to simultaneously model combinations of intrinsic (both modifiable and non-modifiable) factors with incidence of hamstring injury to better understand any co-relationships which may exist. In an attempt to model multiple risk factors with propensity for muscle strain injury in soccer players, Bradley and Portas12 identified flexibility via active hip flexion and knee flexion range of movement (ROM) as modifiable variables which were significant predictors.
Hence, the aim of this study was to investigate the combined influence of a range of physical characteristics and performance capabilities on propensity for hamstring injury over a period of one full season (10 months) in a squad of English Premier League soccer players.
Section snippets
Methods
Thirty six healthy, male, elite, professional footballers (mean ± SD; age: 22.6 ± 5.2 years; height 1.81 ± 0.08 m; mass 75.8 ± 9.4 kg; lean mass 69.0 ± 8.0 kg) from an English Premier League soccer club gave written informed consent to participate in the study. Prior to participating in this study, eleven (31%) subjects had experienced at least one incidence of previous hamstring injury. Ethical approval for this study was granted by the University Institutional Review Board.
Pre-season tests were conducted
Results
A total of 104 injuries were recorded for all participants (n = 36), of which 14 (13.5%) were disruptions to the hamstring musculature (nine Biceps Femoris, five Semitendinosus; grade 1, 2 or 3). This is comparable to that reported by others6 in previous work. Of the 14 incidences of hamstring injury recorded, three were sustained by the same player, the remaining 11 being single incidences for different players. Twelve injuries resulted in less than 14 training days missed and 2 resulted in 14
Discussion
To the best of our knowledge, this study was the first to attempt to simultaneously model the effect of physical and performance characteristics on individual propensity for hamstring injury in elite level soccer players. Using multivariate techniques, a final model containing four independent variables (age, active ROM, explosive power and lean mass) demonstrated a strong combined influence on individual propensity for injury as the model had a capacity to correctly classify 88.6% of cases.
Of
Conclusion
These findings extend the existing knowledge in the area of injury prevention for those involved in the daily training of elite athletes, particularly soccer players and adds quantifiable support to the discussion that mechanisms of hamstring injury are indeed multifactorial. We have demonstrated that older, more powerful athletes with reduced range of motion are potentially at greater risk for hamstring injury. Reduced lean mass, although not significantly contributing to our model should also
Practical implications
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Powerful, older soccer players with reduced active hip flexion range of motion are more susceptible to hamstring injury.
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Results from screening of players can be used to identify individual physical and performance limitations which could contribute to increased injury susceptibility.
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Individualised conditioning plans based on screening results should be used to help to minimise risk of hamstring injury.
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Training for older players should be adapted to allow time to perform activities which will
Acknowledgement
There has been no external financial assistance with this project.
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