More Conventional Wisdoms Bite the Dust (Part II)
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Some time ago in this space (Article #35) I challenged the wisdom – conventionally-held throughout running circles – of using the “hurdler’s stretch” as a means for improving the flexibility of the hamstring muscles. I explained then my reasons for questioning the value of this technique, basing my objections on anatomical and physiological considerations. While that column looked at a very specific technique, a new paper published recently raises a more general question: Is there any value in stretching at all?
I have little doubt that an informal survey of runners would support an affirmative answer to that question. Ask any runner if he/she stretches and the answer invariably is either “Of course” or “No – but I know I should.” If you ask why they feel they should stretch, the reply would probably include “to prevent injury” or “to lessen muscle soreness” or “to improve performance.” How do they know this? Most likely, simply because it’s something they’ve heard over and over again. But who exactly has been saying this? And is there any scientific evidence to support it?
In a recent issue of the British Medical Journal (August 31, 2002), Herbert and Gabriel asked that very question. They performed a systematic review of the research that has been conducted to determine if stretching (1) reduces the amount of muscle soreness associated with exercise; (2) reduces the risk of injury, and; (3) improves athletic performance.
After crunching all the numbers from all the studies, the authors concluded the following:
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- Stretching before and after exercise has no effect on delayed-onset muscle soreness (DOMS).
- Stretching before exercise does not significantly reduce risk of injury.
- At present, there is not enough good evidence to adequately determine if stretching improves athletic performance.
As usual, there are critics of this paper who challenge the methodology of the review, the study sample, etc.
But earlier reviews of the literature (Shrier, British Journal of Sports Medicine 2000; 34 and Clinical Journal of Sport Medicine, Oct. 1999) support the second conclusion even more forcefully, analyzing both clinical and basic science data to refute the notion that stretching confers some level of immunity from injury. And some studies were cited in these reviews that even contend that stretching may actually be harmful!
So where did this conventional wisdom regarding stretching come from? I suspect it most likely emerged as result of perceived personal experience. I believe the critical perception in this case is one that most runners have experienced in the first few minutes of running, comparing those days that we stretch beforehand to those days that we just head out the door “cold.” Almost always, our comfort level in the former case is greater than in the latter, at least until we warm up, so it “stands to reason” that our muscles are better prepared for the activity and thus less likely to be injured. Unfortunately, reason does not always equal veracity, as the results of the studies indicate.
On the other hand, others have suggested that improving flexibility in general can benefit performance, so a regular routine of stretching may achieve that goal. Since there is as of yet no compelling evidence to the contrary, we can at least continue our stretching “habit” in the hope that we will be able to run faster.
Confusing? Yes, as is most of the evidence we seem to hear from studies on a weekly, if not daily, basis. My bottom line: go ahead and stretch if you feel it helps you in some way, but do it with realistic expectations of what it can and cannot do for you.