Thursday, November 11, 2010

The value of stretching?

Ask any 10 runners about their stretching habits and you are likley to get 10 different answers. This press release is a little old, but, the USATF released the results of a study they sponsored looking at the effect of stretching prior to running. The full dataset has yet to be published, but the USATF website does have a PDF up with some more data than just is what is in the press release.

In general, follow-through was low (only 51% of runners stuck to their assigned stretch vs. no stretch routines). The authors try to make some distinctions about serious vs nonserious, injuries diagnosed by a medical professional vs. not. etc.

Bottom line appears to be that stretching does not significantly reduce or increase your risk of injury, but there is a signal of harm from the people who were forced to switch (ie: used to stretch and were assigned to no stretching). So do what you do and stay tuned for more science!

To stretch or not to stretch? That's a question millions of runners ask themselves daily, but results from a USA Track & Field-sponsored clinical trial involving close to 3,000 runners confirm there is no difference in the risk of injury for those who stretched before running and those who did not.

The study randomly assigned people to perform a specified pre-run stretching routine or to perform no pre-run stretching for a period of three months. Those people who completed the study and complied with their group had the same risk of injury (16%) regardless of which group they were in. Overall, stretching did not provide protection against injury.

The study manager, Alan Roth, Ph.D., said, "For the study's specified pre-run stretching routine that millions of runners commonly use, the study puts to rest claims for and against it, but the devil is in the details. Using scientific method, we have arrived at some overall conclusions and learned some important details. If you've been doing pre-run stretching, it is best to keep doing it. A surprise finding was that many variables that we thought would strongly influence injury rates, didn't."

"For example, injury rates among women and men were similar while mileage, flexibility or level of competition also did not appear relevant. In general, younger runners fared no better than the older runners."

The study's principal investigator, Dr. Daniel Pereles, a Maryland-based orthopedist, said that participants provided information on many relevant variables when they enrolled in the study, permitting a thorough analysis of potential risk factors for injury. Participants provided information on such things as age, gender, usual stretching regimen, miles run per week, years running, warm-up activities, measurements of flexibility, concurrent diseases and medications, level of competition and so on.

Two of the variables recorded were found to strongly influence injury rates; people with a higher body-mass-index were more likely to be injured as were people with a recent or chronic injury prior to participating in the study. Participation was limited to runners who had no injuries for the six weeks prior to the study.

One additional risk factor was identified for people who informed us they normally stretch before they run. If they were assigned to stretch, they had a low risk of injury but if they were assigned not to stretch, the injury risk was double those who kept stretching. It's this result that most startlingly exhibits why people consider stretching to prevent injury.

This study shows that those who are comfortable with their pre-run stretching routine should maintain it. They risk injury if they discontinue their pre-run stretching. For runners comfortable without pre-run stretching, they don't necessarily improve their injury protection by starting a pre-run stretching routine.

Darby Thompson, the study statistician, commented, "With the number of runners who contributed to this study, we have shown that the difference in injury rates between those performing pre-run stretching and those who did not is negligible. Although we identified other very important risk factors (weight, prior injury, stopping a stretching routine), because this study was specifically investigating the effect of pre-run stretching, other risk factors may influence injury rates but were not identified. More studies like this one should be conducted to confirm or refute the importance of other risk factors."

For more details or to read the clinical findings, visit

August 22, 2010

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