Leaky Muscles Sap Strength, Study Shows

Discovery May Lead to New Drug Treatment for Heart Failure

From the WebMD Archives

Feb. 11, 2008 -- Exercise is good for you, but overdoing it may temporarily sap muscles of calcium and strength, a new study shows.

"The study does not mean exercise is bad for you," Columbia University's Andrew Marks, MD, says in a news release.

The findings might do more than explain why muscles need rest after intense training. The research could also lead to a new drug for heart failure.

Marks' team put mice on an intense training regimen that included swimming in a pool and scampering along a treadmill.

During high-intensity exercise, the mice's muscles leaked calcium, and when that happened, the mice's muscle endurance nose-dived. Their muscle strength recovered with three days of rest.

The researchers found similar calcium leakage from muscle biopsies taken from people who biked at an intense pace for three hours per day for three days.

Exercise has "numerous positive benefits," Marks and colleagues write. "On the other hand, exhausting exercise, such as that performed by a marathon runner or a long-distance cyclist, results in significant muscle damage and can impair task performance for days or weeks."

New Heart Failure Drug?

Athletes can rest to let their muscles regain their strength. But people with heart failure may experience the same calcium leakage and weakness while idle.

"People with chronic heart failure are subject to this same kind of muscle leak and damage constantly, even without doing any exercise," Marks says in a news release.

Marks and colleagues have already tested the experimental drug in rodents that developed heart failure because of a heart attack. The researchers plan to test the experimental drug in people with heart failure, according to the news release.

WebMD Health News Reviewed by Louise Chang, MD on February 11, 2008

Sources

SOURCES:

Bellinger, A. Proceedings of the National Academy of Sciences, Feb. 12, 2008; vol 105: pp 2198-2202.

News release, Proceedings of the National Academy of Sciences.

News release, Columbia University Medical Center.

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