Hamstring injuries are a major problem in sport, both because of their frequency and the fact that they are known to be highly recurrent (up to 30%). These injuries do not feature prominently in hospital-based injury data collections because they are generally treated outside of the hospital setting, but injury surveillance studies conducted directly with sporting teams highlight that hamstrings are the most common muscle injury. Hamstring injuries place a considerable burden on players who sustain them because they require extensive treatment and rehabilitation before full recovery and this impacts on players’ ability to continue to play their sport. In certain professional sports, hamstring injuries are a particular concern because players who sustain them are then unavailable for competition for a considerable time and this leads to major costs to the sports delivery system (e.g. when a star player is no longer available to play in matches in a national or international competition). Whilst most common in the higher competitive levels, they generally occur in sports involving high-speed running and/or kicking actions (e.g. all football codes, martial arts, dancing and sprinting).
Given the significance of this problem to sports medicine, the February 2011 issue of the British Journal of Sports Medicine has a focus on hamstring injuries with the editorial by Malliaropolus and Mafulli describing the clinical and research challenges associated with this condition.
Of course, identification of appropriate preventive solutions requires knowledge of the mechanism and causal factors associated with their occurrence. The BJSM issue presents debate from two perspectives: the first being that hamstrings are most susceptible to injury during the late swing phase of sprinting (see paper by Chumanov and colleagues). These authors argue that this means that athletes should be encouraged to undertake conditioning exercises that involve active lengthening contractions of their hamstring muscles to prevent them being injured. Orchard provides an opposing view that hamstring injuries are most susceptible in the early stance phase of sprinting and so are more related to excessive ground reaction forces during running. The review by Mendihuchia et al provides a new conceptual model for hamstring strain injury that proposes interactions between flexibility, strength, core stability, fatigue, anatomical architecture and previous injury history as being important for hamstring injury occurrence.
De Visser and colleagues report a systematic review of studies describing risk factors for recurrent hamstring injury and conclude that players with a larger (more severe) initial injury and those undergoing certain surgical procedures were more likely to re-injury their hamstring. They also found that the published evidence was in favour of rehabilitation programs incorporating agility and stabilisation exercises rather than strength/stretching exercises for re-injury reduction.
The challenge is now to take the existing knowledge about hamstring injury aetiology (for both the initial and subsequent injuries) and to use this to implement and evaluate new intervention strategies that address these risk factors.
We have previously shown in our studies in Australian football that older players have a greater susceptibility to hamstring injuries than younger ones (1) and some of the factors from the Mendihuchia et al model are also known to vary with age and so may explain this. The implementation of preventive programs delivered at a club to team members of varying ages will therefore need to be carefully planned so as to most benefit those older players who need them, without compromising the protective potential for younger players.
It is unlikely that there will be one unique intervention solution for all, and this will mean that there are going to be significant implementation and targeting challenges for coaches who are the major deliverers of safety programs in sport. There is clear scope for knowledge about how to modify or refine injury prevention measures to different target groups , whilst maintaining intervention fidelity, in other settings to now be applied to sport.
Additional Reference
(1) Gabbe BJ, Bennell KM, Finch CF. Why are older Australian football players at greater risk of hamstring injury? Journal of Science and Medicine in Sport. 2006; 9:327-333.
Caroline Finch is an injury prevention researcher from the Australian Centre for Research into Injury in Sport and its Prevention (ACRISP) within the Monash Injury Research Centre, Monash University, Australia. She specialises in implementation and dissemination science applications for sports injury prevention. She is the Senior Associate Editor for Implementation & Dissemination for the British Journal of Sports Medicine and a member of the Editorial Board of Injury Prevention; both journals are published by the BMJ Group. Caroline can be
followed on Twitter @CarolineFinch.