When most of us think of stretching, we're imagining at a minimum jogging, and probably something more like downhill skiing or sprints. But when University of Michigan researchers Nicole Lockhart and Susan Brooks talk stretching, their real interest is how to condition older folks' muscles so they'll eventually be willing to do even a little exercise to garner all the benefits that will follow.

"The elderly are far more susceptible to contraction-induced injury," notes Lockhart, lead author in two related papers being presented in American Physiological Society sessions at Experimental Biology in San Francisco. "Sometimes just by normal activity or a sudden movement a leg will jut out too far and they'll suffer a minor injury, but they'll be wary of further damage," she said.

Protect those muscles, as minor injuries may be cumulative

Brooks, her adviser, added: "We think that cumulative muscle injury may contribute to the loss of muscle mass as we grow old. So protecting muscles at all times is a good thing. And understanding how stretching increases resistance to injury will really help to do this."

The team had previously shown that stretching decreased muscle injury in mice when stretches were performed anywhere from one hour to 14 days (yes days) prior to exercise. But they didn't know why. What is known is that while stretching muscles produce nitric oxide (NO), a common signaling molecule. NO increases blood flow and decreases force during submaximal contractions, and also can modulate inflammation.

NO protects without stretching; but without NO, stretching doesn't seem to protect

So they tested whether the anti-inflammatory effects of NO were involved in the protection provided by s
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Contact: Mayer Resnick
mresnick@the-aps.org
301-634-7209
American Physiological Society
3-Apr-2006