7 : Does stretching help prevent injuries ?

Over the past 30 years, sport medicine professionals have promoted stretching as a way to decrease the risk of injury. Two potential mechanisms are often proposed by which stretching could decrease injury: a direct decrease in muscle stiffness via changes in passive visco-elastic properties, or an indirect decrease in muscle stiffness via reflex muscle inhibition and consequent changes in visco-elastic properties due to decreased actin-myosin cross bridges. These changes in muscle stiffness would allow for an increased range of motion (ROM) around a joint (i.e. “flexibility”*), which is believed to decrease the risk of injury. Despite these claims, new research has challenged some of these concepts. First, stretching must be differentiated from range of motion. There are many individuals who have excellent range of motion but never stretch, and many individuals who stretch but continue to have limited range of motion. Therefore, different injury rates in people with different ranges of motion may not be related to the effect of stretching but rather occur because of underlying variations in tissue properties (for example strength), anatomy, etc. To understand the specific effect of stretching, then one should limit the review to studies that directly look at that intervention. Second, stretching immediately before exercise may have different effects than stretching at other times. These should be considered separate interventions, and completely different from studies on flexibility. Whereas there is a considerable amount of clinical data on stretching immediately before exercise, there is much less data on stretching at other times.