Leaky Muscles Sap Strength, Study Shows
Discovery May Lead to New Drug Treatment for Heart Failure
Feb. 11, 2008 -- Exercise is good for you, but
overdoing it may temporarily sap muscles of calcium and strength, a new study
"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
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
"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 theÂ experimental drug in people with heart failure,
according to the news release.