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  • Response to Jeff McBride (elastic energy utilization)

    On Fri, 9 Oct 1998, Jeff McBride wrote:

    > I do not know to which fallacy you are referring in the athletic
    > training community (exercise science community). You are discussing two
    > different issues in your e-mail. ...

    No. I only discussed one issue which was the attribution of extra
    potential energy achieved in a counter movement jump over that achieved in
    a squat jump to the utilization of stored elastic energy. If you re-read
    my posting more carefully you should see that I stated that SOME of that
    extra energy IS probably due to the utilization of stored elastic energy
    but there are other contributing factors not related to either stored
    energy or to neural facilitation. Unless you are willing to form the
    contrary argument that you CAN quantify the amount of stored elastic
    energy recovered in human movement with the method proposed by Komi and
    Bosco (1978), I fail to see the point of your posting.

    > Irrespective of this I am skeptical of computer or mathematical
    > models when spring constants for the elastic potential of skeletal muscle
    > are derived from single muscle fibres in vitro. Is this ...

    Again, if you read my posting more carefully you will notice the the
    mathematical model that I referred to had NO ELASTICITY! In laboratory
    experiments involving biological tissues you cannot eliminate elasticity
    completely and this is the beauty of a mathematical proof. If you can
    prove that the counter movment produces more energy in the complete absence
    of strain energy then one cannot attribute ALL of the energy to
    elasticity. At least one additional factor exists and this
    level of proof (mathematical) is unattainable in traditional experiments.

    > exercise science community. I think this issue still needs substantial
    > amounts of additional investigation. The true elastic potential of ...

    This is in total agreement with my posting. Incidentally, I Emailed both
    Marco Cardinale and Jerry Telle asking them to estimate how widespread the
    practice of estimating utilization of stored elastic energy in athletes
    was. At the time of this posting, I have not received a response from
    either of them. Given the problems with the measurement of this
    phenomenon, I hope the practice is not very common and the only purpose of
    my original posting was to alert those that may using the method of its
    potential errors.

    Jim Dowling, Ph.D.
    Department of Kinesiology
    McMaster University
    Hamilton, Ontario
    CANADA

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