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The Story Behind the Pre-Run Stretch Study
By Alan Roth
May/June 2011
For the Washington Running Report
The Pre-Run Stretch Study turned out to be a much bigger job than we even thought it would be, dating back to 2004 when Dr. Dan Pereles told me that doctors didn’t really know the effects of pre-run stretching. It hadn’t been scientifically studied.
The Centers for Disease Control and Prevention (CDC) in Atlanta led a study of 361 studies that compared stretching with other methods to prevent sports injuries and concluded that a large-scale, randomized, controlled study of stretching to determine its proper role in sports was urgently needed.
Pereles, an orthopedic surgeon practicing in Montgomery County, Maryland, said he was going to try to do such a study. About a year later, I inquired how the study was going. He said he couldn’t do it because he needed access to a large number of runners.
At the time, I was head of the grass roots division of USA Track & Field (USATF) and suggested we work together with backing from USATF to reach out to millions of American runners. The USATF President and the CEO [Names???] were very supportive when I presented the idea to them. The organization had never done a national study of any kind. It would be new to all of us.
Granted, I had experience doing surveys, but in developing countries not medical surveys. Dan also had not worked on medical surveys. We were very lucky to obtain the pro bono services of a medical study statistician, Darby Thompson, who was working for Emmes Corp. in Rockville, MD, a company that specializes in large medical studies.
We knew many runners as well as coaches and trainers who had strong feelings about pre-run stretching. Some said, “You must always stretch before your run!” While others advised, “Don’t ever stretch before you run!” But neither side had scientific evidence on which they could base either policy. They just knew they were right.
Since we were all runners, we figured that we could use a waiver to provide liability protection, you know, just like road races do. We soon learned that this is illegal when applied to a medical study on human subjects. In fact, such a medical study has many restrictions.
We needed:
1) Informed Consent form signed by each registrant.
2) Study reviewed and approved by an Institutional Review Board (IRB) of which there are many around the country.
Anticipating a struggle for IRB approval, I took some online courses, “The Protection of Human Research Subjects” and “Responsible Conduct of Research.” We had excellence support from USATF, with Webmaster Keith Lively putting the survey online and my staff counterpart, Andy Martin, helping with the Study Protocol and Informed Consent. We also had the USATF Sports Medicine and Science Committee providing useful input. It was a real team effort.
By now it was already into 2006 and with a major effort reworking the documentation and getting it correct on the Web site, it took another year to launch the online survey. Keep in mind that the three major players: Dan, Darby, and I, all did this gratis in our spare time. With the help of USATF, it is amazing how much we accomplished--without a budget.
The IRB instructed us to end the study when we had an injury divergence of 5% between the randomized stretchers and non-stretchers. The stretchers were to follow a protocol of stretching the quads, hamstrings, and calf muscles for a total of about four minutes. Each participant signed on for three months and was asked to report back on injuries either at the end of the three months or, if injured, three weeks after the injury was incurred.
We really didn’t know how long it would take to get statistically valid results or how many runners we would need in the study to reach a conclusion. We had no serious expectations about the results. Would stretching be protective or not? Maybe stretching would cause injuries. We were anxious to get results, but we had a very long wait. Groups like the RRCA (our official “Outreach Partner”), runnersworld.com, and active.com, plus USATF press releases to recruit runners, helped but it was slow. Apparently, many runners already had a preference to stretch or not stretch so they didn’t participate.
After two years, we had finally collected “quality” data from about half of the 3,000 runners who signed up and we decided that would do the job. Darby told us we had quite a number of statistically-valid findings. We were quite surprised that it was a dead heat:
* Both the stretchers and non-stretchers had the same 16% risk of injury.
So, it really doesn’t matter if you stretch or don’t stretch. At least that is true in a general sense. There needn’t be a rule that everybody should stretch or not stretch.
The study included variables such as gender, age, years running, weight/height, level of competition, warm-up routine, flexibility, racing distance, level of effort, to name a few. Most variables turned out to have no influence on the risk of injury.
We also learned the participant’s stretching habits. That turned out to have the most risk/protection effect of any other variable. If you told us you generally stretch before you run and were put into the stretch group, the risk of injury went down to 11.8%, but if you were assigned to the non-stretch group, the risk of injury went up to 22.3%. That’s a huge difference. So, if you normally stretch before you run, don’t change your routine.
My personal thinking is that stretching provides some protection, but it is in starting a stretching regimen where we saw the problem. Those who told us they normally stretch were already doing it for some time and the start-up risk was behind them. Perhaps those who were injured if they tried stretching had at some time in the past stopped stretching. To stretch, just for the sake of stretching, no longer makes sense.
I personally believe, however, if you have chronic problems with your Achilles or patella tendon, or other specific problem, perhaps stretching for your specific problem would be helpful.
Our study focused on static stretching because that is what most runners do if they stretch before they run. We know there are other forms of stretching and a future study could look at those.
Two of the variables: warming up before running and stretching after running, showed no difference in injury risk. This surprised us but the problem may have been that the numbers of runners checking those boxes were too small to be statistically viable.
We ended up with quite a database that could be mined for identifying other useful characteristics about runners and their injuries. We’ve analyzed some but much more remains. Overall, the response to the study has been very favorable.
Alan Roth, Ph.D., was the Study Manager for this project. For more information: www.usatf.org/stretchStudy/index.asp.