Available research is inconclusive regarding the optimal time to stretch. In addition, strong evidence is lacking with regard to the beneficial effects associated with pre-exercise stretching (e.g., injury prevention or enhanced athletic performance). In fact, research exists to suggest that stretching prior to an athletic activity may decrease power output resulting in diminished physical performance. Some individuals incorporate stretching at the end of the warm-up period, however this practice can be somewhat counterproductive since stretching during the conclusion of the warm-up will cause a drop in heart rate prior to the start of the conditioning segment of the workout session. Consequently, the most appropriate time to stretch tends to be at the end of a workout session. Stretching at the end as part of the cool-down segment is recommended because it is safer and more effective to stretch muscles that are properly warmed and, therefore, more pliable. Also, it will help to further facilitate post-workout recovery.
As chief science officer for ACE, Cedric X. Bryant, Ph.D., FACSM, represents the organization as an international lecturer, writer and expert source. He has written more than 250 articles and columns for various publications, and he has written, co-written or edited 30 books. Dr. Bryant is an authoritative source on health and fitness for several media outlets including the Washington Post, The New York Times, Time magazine, and CNN. He also currently serves on numerous advisory boards including the Institute of Medicine Obesity Solutions Roundtable, the Osteoarthritis Action Alliance Physical Activity Workgroup, and the Medical Fitness Association's Certification Committee.