Abstract
BackgroundWarm-up and stretching are suggested to increase hamstring flexibility and reduce the risk of injury. This study examined the short-term effects of warm-up, static stretching and dynamic stretching on hamstring flexibility in individuals with previous hamstring injury and uninjured controls.MethodsA randomised crossover study design, over 2 separate days. Hamstring flexibility was assessed using passive knee extension range of motion (PKE ROM). 18 previously injured individuals and 18 uninjured controls participated. On both days, four measurements of PKE ROM were recorded: (1) at baseline; (2) after warm-up; (3) after stretch (static or dynamic) and (4) after a 15-minute rest. Participants carried out both static and dynamic stretches, but on different days. Data were analysed using Anova.ResultsAcross both groups, there was a significant main effect for time (p < 0.001). PKE ROM significantly increased with warm-up (p < 0.001). From warm-up, PKE ROM further increased with static stretching (p = 0.04) but significantly decreased after dynamic stretching (p = 0.013). The increased flexibility after warm-up and static stretching reduced significantly (p < 0.001) after 15 minutes of rest, but remained significantly greater than at baseline (p < 0.001). Between groups, there was no main effect for group (p = 0.462), with no difference in mean PKE ROM values at any individual stage of the protocol (p > 0.05). Using ANCOVA to adjust for the non-significant (p = 0.141) baseline difference between groups, the previously injured group demonstrated a greater response to warm-up and static stretching, however this was not statistically significant (p = 0.05).ConclusionWarm-up significantly increased hamstring flexibility. Static stretching also increased hamstring flexibility, whereas dynamic did not, in agreement with previous findings on uninjured controls. The effect of warm-up and static stretching on flexibility was greater in those with reduced flexibility post-injury, but this did not reach statistical significance. Further prospective research is required to validate the hypothesis that increased flexibility improves outcomes.Trial RegistrationACTRN12608000638336
Highlights
Warm-up and stretching are suggested to increase hamstring flexibility and reduce the risk of injury
Using ANCOVA to adjust for the non-significant (p = 0.141) baseline differences, the Limited literature is available to compare the combined effect of warm-up and stretching on hamstring flexibility. de Weijer et al [28] compared the effect of warm-up and static stretching at multiple intervals up to 24 hours later on the hamstring flexibility of uninjured individuals
Our results demonstrated that combined warm-up and static stretching increased flexibility; we did not look at static stretching in isolation and cannot comment on whether this is more effective at increasing flexibility than warm-up alone
Summary
Warm-up and stretching are suggested to increase hamstring flexibility and reduce the risk of injury. Stretching is usually incorporated pre-exercise as it has been suggested to improve muscle flexibility, prevent muscle injury and enhance physical performance [4,5,6,7]. Dynamic stretching involves moving the limb from its neutral position to end range, where the muscles are at their greatest length and moving the limb back to its original position. This dynamic action is carried out in a smooth, controlled manner and is repeated for a specified time period [16]
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