For all of my running career (34 years), I've done my stretches before I run. When I started running, everyone stretched before they ran. However, since then it has become a controversy whether one should stretch before or after. I've been thinking about switching for quite a while, and after participating in a discussion on stretching in the running.about.com forum, I've decided to try stretching after I run. I will do more walking to warm up better before I run.
Some runners believe that stretching before a run helps the muscles to become loose and warm, ready to propel the runner. Other runners, however, claim that research shows that there is no advantage to stretching before a run. I haven't seen good test results about that, so I don't know if those claims about research are true.
However, my primary reason for stretching is to strengthen my muscles, and I think that that can be done anytime during the day. So, I thought I'd try stretching after and see how it goes. Today was my first day to stretch after.