When I used to work out, I got so incredibly fucking sick of people telling me I needed to stretch. Bullshit. I never stretched and never had a problem. There are some other popular myths I'd take issue with, but I'll limit myself to this one for today. In un-trained runners, static stretching decreased efficiency and performance. However in a follow-up study using trained runners, there was no effect on either efficiency or performance and did increase flexibility. So at this point, the jury is still out regarding the benefits or static stretching - or lack thereof. An Italian study (no cite, read in Sept Popular Mechanics, page 20) claims the reason for the reduced efficiency was that it "change the force-transmission properties of muscle fibers and alter the brain signals to muscle". However dynamic stretching is another can of tofurkey.