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View Full Version : Response to Jeff McBride (elastic energy utilization)



James Dowling
10-14-1998, 11:08 PM
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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