Sept. 10, 2010 -- Some runners swear by their pre-run stretch as a sure-fire way to run better and stronger and reduce their risk of injury in the process.

But according to a new study, distance runners who stretch before a run may not perform as well and may spend more energy than runners who skip the stretch.

''Overall, I don’t think it's worth it to stretch before a run," researcher Jacob M. Wilson, PhD, assistant professor of exercise science and sport studies at the University of Tampa, tells WebMD. "After a run, if someone is trying to work on flexibility, that's fine."

Although his study was done only on male runners who were young and highly trained, Wilson speculates that the findings would apply to recreational runners and to female runners as well.

The study is published in the Journal of Strength and Conditioning Research.