A recent study published in the Journal of Strength and Conditioning Research suggest that pre-exercise static stretching may hamper athletic performance.
Included in this study 10 male college athletes who participated in a 60 minute treadmill run on two occasions. Participants of the first run performed static stretches for 16 minutes prior to exercise. While participants of the second run simply sat quietly for 16 minutes. The athletes from each group instructed to run as long as possible. Researchers found that performance was significantly greater in the non- stretching athletes with significantly greater energy expenditure.
Why does stretching prior to exercise hinder performance? According to Jason Seigler PHd of University of Hull in England”when you stretch prior to exercise or you are not warmed up you stimulate the protective mechanism within the muscle. Depending on the intensity of the stretch you override the muscle spindles and inhibit afferent neural pathways to the brain.
A better suggestion from running coach/personal trainer is to perform a more dynamic stretch that also acts as a warm up. An example of this type of exercise is a walking lunge, high knee running, butt kicks,side shuffle, straight leg March, and leg swings.