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  • news: muscle fatigue

    The following may be of interest to Biomch-L subscribers.


    Ton van den Bogert, Biomch-L co-moderator


    Chang W. Lee/The New York Times
    February 12, 2008

    One of the great unanswered questions in physiology is why muscles get tired.
    The experience is universal, common to creatures that have muscles, but the
    answer has been elusive until now.

    Scientists at Columbia say they have not only come up with an answer, but have
    also devised, for mice, an experimental drug that can revive the animals and
    let them keep running long after they would normally flop down in exhaustion.

    For decades, muscle fatigue had been largely ignored or misunderstood. Leading
    physiology textbooks did not even try to offer a mechanism, said Dr. Andrew
    Marks, principal investigator of the new study. A popular theory, that muscles
    become tired because they release lactic acid, was discredited not long ago.

    In a report published Monday in an early online edition of Proceedings of the
    National Academy of Sciences, Dr. Marks says the problem is calcium flow
    inside muscle cells. Ordinarily, ebbs and flows of calcium in cells control
    muscle contractions. But when muscles grow tired, the investigators report,
    tiny channels in them start leaking calcium, and that weakens contractions. At
    the same time, the leaked calcium stimulates an enzyme that eats into muscle
    fibers, contributing to the muscle exhaustion.


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