Stretching before a run neither prevents nor causes injury, according to a study presented at the 2011 Annual Meeting of the American Academy of Orthopaedic Surgeons (AAOS).

More than 70 million people worldwide run recreationally or competitively, and recently there has been controversy regarding whether runners should stretch before running, or not at all. This study included 2,729 runners who run 10 or more miles per week. Of these runners, 1,366 were randomized to a stretch group, and 1,363 were randomized to a non-stretch group before running. Runners in the stretch group stretched their quadriceps, hamstrings, and gastrocnemius/soleus muscle groups. The entire routine took 3 to 5 minutes and was performed immediately before running.

The study found that stretching before running neither prevents nor causes injury. In fact, the most significant risk factors for injury included the following:

history of chronic injury or injury in the past four months;

higher body mass index (BMI); and

switching pre-run stretching routines (runners who normally stretch stopping and those who did stretch starting to stretch before running).

"As a runner myself, I thought stretching before a run would help to prevent injury," said Daniel Pereles, MD, study author and orthopaedic surgeon from Montgomery Orthopedics outside Washington, DC. "However, we found that the risk for injury was the same for men and women, whether or not they were high or low mileage runners, and across all age groups. But, the more mileage run or the heavier and older the runner was, the more likely he or she was likely to get injured, and previous injury within four months predisposed to even further injury," he added.

Runners who typically stretch as part of their pre-run routine and were randomized not to stretch during the study period were far more likely to have an injury. "Although all runners switching routines were more likely to experience an injury than those who did not switch, the group that stopped stretching had more reported injuries, implying that an immediate shift in a regimen may be more important than the regimen itself," he added.

The most common injuries sustained were groin pulls, foot/ankle injuries, and knee injuries. There was no significant difference in injury rates between the runners who stretched and the runners who didn't for any specific injury location or diagnosis.