THE ROLE OF EXERCISE IN THE PREVENTION OF HAMSTRING INJURY

BY ALISON TOOLEY, MCSP BSC (HONS)

INTRODUCTION Hamstring strains are one of the most common injuries in sport (1). They account for approximately 16–23% of injuries in Australian Rules football (2), resulting in an average of 90 days and 15–21 matches missed per club per season (3). With slow healing times, hamstring strain can be one of the most frustrating injuries for coaches and athletes. Therefore, the ability to prevent hamstring injury is highly important. Numerous risk factors for hamstring muscle strain have been identified; these include muscle weakness, lack of flexibility, poor warm- up, muscle fatigue, and poor lumbar posture and core stability (4). This article evaluates the available

evidence surrounding exercise to prevent hamstring injury and indicates potential pre-habilitative regimes for athletes. The possible benefits and risks are discussed in relation to long-term flexibility training, eccentric strength training and pre-game stretching of the hamstring muscles.

DISCUSSION Stretching before exercise is widely considered an important part of the warm-up to prevent injury. However, there is no clear scientific evidence to suggest that there is a link between stretching and injury prevention; nor is there any consensus on protocol for stretching regimes (5). It is thought that stretching and the subsequent decrease in stiffness may lessen the load across the muscle–tendon unit during sports with high stretch- shortening cycle movements such as running, and may increase the ability of the tendon to absorb energy (6),

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This article evaluates the available evidence surrounding exercise to prevent hamstring injury and indicate potential pre-habilitative regimes for athletes. The possible benefits and risks are discussed in relation to long-term flexibility training, eccentric strength training and pre-game stretching of the hamstring muscles. A lack of good- quality evidence leads to conflicting information. However, studies suggest that incorporating eccentric strength training may reduce the incidence of hamstring injury. There is conflicting evidence regarding the need to increase overall flexibility outside pre-exercise time, although the evidence suggests that pre-exercise hamstring stretching may not reduce hamstring injury

theoretically reducing the chance of injury. The exact mechanism by which this occurs has not been investigated fully.

Study 1 Whatman and colleagues concluded in a clinical trial that an isolated bout of hamstring stretching produced a small change in knee range of motion and stiffness (7). Nine participants completed the study. Recorded electromyography activity of the quadriceps and hamstrings ensured passive movement during a baseline test for knee extension using a Kin-ComTM dynamometer.

HAMSTRING INJURY CAN BE REDUCED WITH PREVENTATIVE TRAINING REGIMES

EVIDENCE SHOWS THAT THE INCIDENCE OF

Figure 1: Starting the Nordic hamstring exercise

sportEX medicine 2009;39(Jan):12-16

This baseline was then followed by four 20-second static stretches of the hamstring, performed by a physiotherapist, manually extending the knee while seated. Range of motion and stiffness testing was repeated immediately post-stretch and at five-