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Loren Chiu
01-26-2002, 05:31 AM
Biomech-L subscribers,

I have a question about the mathematical calculation of mechanical work
and power during resistance exercise.

We have a set-up that involves using a force platform to measure force
and a linear position transducer to measure displacement. All data are
sampled at 500Hz.

>From the vertical force data and the displacement data, we'd like to
calculate mechanical work and power of the movement of the centre of
mass. The question is which approach to use:

1. Differentiate displacement wrt time to obtain velocity. Multiply
force and velocity channels to obtain power. Integrate power wrt time
to obtain work. Winter (1990) suggests this integration method to
calculate work.

or

2. Multiply force and displacement channels to obtain work.
Differentiate work wrt time to obtain power.

I've calculated work and power using both approaches and overlayed the
respective curves (work-time(1) vs. work-time (2), etc.) and they do
not replicate each other, indicating that the two approaches have
different results.

Any help would be appreciated.

Regards

Loren Chiu
Graduate Assistant
Exercise Biochemistry Laboratory
Human Performance Laboratories
The University of Memphis

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