That is the question. For years, runners have been taught to stretch after every run. I've always done it, and always thought I was doing a good thing. It feels good and it would seem to be the right thing to do. Lately, however, I'm starting to change my thinking.
A good deal of evidence is starting to suggest that static stretching--the kind we all do post-run--may be doing more harm than good. It seems that when you stretch a muscle statically, you may actually be causing micro-tearing in the muscle. This leads to weakening, and the weakening can lead to injury. Not what anybody wants, to be sure.
So what should you do instead? Try performing dynamic moves at the beginning of a run, for one. There are lots of good articles out there that can lead you through some of these moves--about 10 to 15 minutes of high knee walking, butt kicks, leg swings, etc., can get you out the door ready to run. Then post-run, try walking for about 10 minutes to actively cooldown and get your legs ready to stop.
Yoga and Pilate's are another great way to stretch. These forms of exercise produce slow, easy motion that can help keep you a bit looser. Again, however, make sure you come in with warm muscles to these classes--just 10 to 15 minutes of pre-workout walking or easy cycling can do the trick. Then approach the class with patience, working through the moves at an unhurried, relaxed pace.
As athletes, we are on a constant learning curve. After 13 years of running, I feel that I still have so much to learn. This rethinking of stretching is just one example of why it pays to stay on top of the latest findings and information available.