The advice to stretch, warm-up, and cool down to prevent exercise and sports related injuries and soreness has been the conventional wisdom for years. The belief is that a stretching routine get's you limber and increases soft-tissue circulation, which not only improves athletic performance, but also reduces the risk of injury.
However, in the past few years, the conventional wisdom has been challenged by controlled studies. The results have been surprising. Though there's a smattering of evidence suggesting that there might be some possible benefit to stretching or other peri-exercise rituals, the larger and better studies have found nothing of the sort.
A controlled study of 900 military recruits published in 2003 found no reduction in injury rates between those assigned to a pre-exercise stretching regimen and those that were assigned to no stretching, results that were identical to the findings of an earlier study involving 1500 military recruits and a still earlier one which enrolled almost 1100 subjects. All of the recent large scale studies have had the same results, and other studies looking at the impact of stretching on muscle soreness have been similarly disappointing.
A systemic review of the subject was published in 2002. After evaluating those studies published in the peer-reviewed literature that met pre-established quality criteria, the authors concluded:
|...Stretching before or after exercising does not confer protection from muscle soreness. Stretching before exercising does not seem to confer a practically useful reduction in the risk of injury...
In the laboratory, perfusion studies have found that stretching only minimally increases blood flow through muscle tissue and has no significant impact on tendon or ligament blood flow, which seems to refute much of the speculation underlying the purported benefits of stretching.
There is insufficient data as of yet to determine the impact stretching and warm-up routines may have on sports performance. It's also possible that stretching may confer some benefits on specific activities that have not been studied, such as skiing or martial arts . Finally, there is a relative paucity of data on women and stretching, as most of these trials were conducted on men. But for now, there is little scientific data to support a general recommendation for stretching pre or post exercise as the data we have has shown no benefit. There is even some preliminary data to suggest that stretching may actually increase
the risk of certain types of ligament injuries, possibly owing to increased tendon laxicity arising from stretching.