The Miami Herald ran an interesting article questioning the benefit of stretching before a workout. For the most part, the article makes some excellent points.
Contrary to popular belief, a large body of research shows that stretching prior to exercise has no effect on decreasing injury risk. Yes, improving flexibility can help in injury prevention depending on the activity. Tight muscles have been implicated as a potential cause of various injuries, and improving flexibility can help to reduce this possibility. However, it doesn’t matter when the stretching is done. The only concern is that you achieve adequate range of motion for the task you want to perform. As the Nike ad says, “Just do it!”
Most importantly, stretching is best performed after a good warm-up. This helps to reduce joint viscosity, ensuring that muscles and connective tissue are sufficiently prepped to endure passive and/or active lengthening. Some light aerobic activity performed for 5 or 10 minutes will accomplish this task well. Take home message: Don’t stretch a cold muscle.
Interestingly, there actually is some evidence showing that stretching before a workout can have a negative impact on exercise performance. This is most applicable to activities requiring high-force output, such as low rep weight training, sprinting, and jumping. I won’t bore you with the details on the how’s and why’s, but bottom line is that various indices of power have been shown to be reduced when a forceful activity is performed immediately following a stretching session.
However, caution needs to be used when applying much this research to general fitness-oriented workouts. First, most of the studies in question used excessive stretching protocols, in some cases spending upwards of 30 minutes stretching a single joint. This has limited applicability to the stretching protocols used by the majority of fitness enthusiasts.
Moreover, the studies are specific to high-power activities. This has questionable correlation to the moderate-to-high repetition resistance training performed by many gym goers, and virtually no correlation to sub-maximal cardiovascular exercise. More research is needed to achieve a better understanding of the subject. This is yet another instance that shows the importance of reading the actual research rather than simply listening to the media’s interpretation of science.