Stretching

You should stretch before you exercise

Almost anyone who works out, plays sports, runs, or engages in regular exercise will tell you that you should absolutely stretch first. Stretching is supposed to help you perform better. Even more importantly, stretching is supposed to prevent injuries. The idea of not stretching before a run or before a game is anathema to most athletes. Entire books are devoted to describing the best ways to stretch, and careers of coaches and trainers have been built upon their knowledge of proper stretching. How could we even suggest something so dangerous as not stretching before exercise?

As much as it may shock you, there is good scientific evidence that stretching does not reduce your chance of being injured during sports or exercise. Several meta-analyses or comprehensive reviews have been done to compile all of the studies on this subject. In a 2004 systematic review by scientists at the Centers for Disease Control, the authors reviewed 361 studies and identified six that most rigorously tested whether stretching reduced the chance of getting injured. Most of these studies tested the effects of stretching for people going through basic training in the military or for high school and college football players. The combined verdict from these studies was that the enhanced flexibility created through stretching did not reduce the injuries seen in sporting or fitness activities. So even if you stretched carefully, you were still just as likely to get a pulled muscle as a person who did not stretch first.

Even if stretching will not help you prevent injuries, you still may cling to your stretching routine because you think it prevents your muscles from getting sore. In particular, many people stretch before or after exercise or at both times in order to prevent their muscles from being sore the day after they exercise. Another excellent systematic review compiled the results of ten randomized trials that looked at the effect of stretching before or after physical activity on muscle soreness. These were not great studies—they were small and of questionable quality—but they do give us some idea of what stretching does for muscle soreness. And the answer is: very little! Stretching had very little to no effect whatsoever on muscle soreness in half a day to three days after the physical activity.

There is also evidence that stretching has some negative effects. Stretching does improve your flexibility, but this is not always a good thing. Instead of improving your performance, stretching has been associated with temporary deficits or decreases in your strength, with increased blood pressure, with worse jumping performance, and with worse flexing strength of your ankles. These is also some suggestion that people who are more flexible do not run as well, but these results are mixed.

Let’s summarize the research: Stretching does not prevent injuries. Stretching does not keep your muscles from getting sore later on. Stretching can actually make you perform worse. This seems like craziness! Rachel can hear the gasps of horror and disbelief from her fellow runners (most of whom are much faster than she is and who also spend a lot of time stretching). And yet study after study tells us that you are not going to get any benefit out of stretching before you run. One of the most recent studies, done by the USA Track and Field organization, looked at about 1,400 runners who were randomly assigned to stretch or not stretch before their runs. Even this pro-running organization found that stretching did not prevent running injuries.

What about warming up? Studies of warming up look at activities other than stretching, such as walking, running, or calisthenics, that are done before a more vigorous athletic activity. The evidence on warming up is not as clear. While study after study tells us that stretching before exercise does not prevent injuries, some of the studies of other forms of warming up before exercise show that this practice will reduce injuries. In a systematic review compiling all the randomized, controlled studies (i.e., the good studies) of warming up before exercise, three of the studies showed that warming up first did reduce injuries later. The other two studies did not find any effect from warming up. The conclusion was that there is not sufficient evidence to say whether a routine warm-up before your exercise will help you prevent injuries, but there is some suggestion that this might work.

Continue those warm-ups if you must (although we’ll have to keep compiling the studies on whether or not that really works), but stretching is not going to help you be a better or safer runner!