During my high school track days, no runs would start without first a team stretch. We performed all the stretching staples to help relax and release our quads, hamstrings, and upper-body muscles, and only then after would we be allowed to hit the track.
Back then, we were told to do stretches in order to warm up our muscles and get them ready to hit the ground running. Now when I run, I usually just throw on my shoes and start out with a jog to warm up. And when I strength train with my Crunch trainer, he only has me warm up with a little cardio before we begin, usually five minutes on the elliptical. While warming up is essential before you begin any workout, he says, static stretching before exercising isn't necessary. My trainer does say that any preworkout stretching should be active or reserved to a foam roller. (He also adds that stretching after a workout is imperative. It helps muscles repair themselves, which reduces soreness.) Adding to his advice are multiple studies that say stretching a cold muscle isn't safe because it's more likely to tear and it's less effective. New research has found that stretching before exercise may make muscles contract and become shorter, the exact opposite of what you want before working out.
Many people, however, find stretching beneficial to their workout and say that it can help reduce injury or keep them looking toned and lean. What's your side in the debate?