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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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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To unsubscribe send SIGNOFF BIOMCH-L to LISTSERV@nic.surfnet.nl

For information and archives: http://isb.ri.ccf.org/biomch-l

---------------------------------------------------------------