Doctoral Dissertations

Date of Award

8-1983

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Life Sciences

Major Professor

Hugh G. Welch

Committee Members

Edward T. Howley, B. Don Franks, Roland Bagby

Abstract

This study consisted of two sets of experiments. It was designed to determine if an optimal or most efficient pedal rate in cycling exists, and if so what variables determine the optimal pedal rate. Five trained bicycle racers were used as subjects for the study. The first experiment was a series of five maximal ergometer tests at different pedal rates (40, 60, 80, 100, and 120 RPM). The subjects rode to exhaustion at progressive loads while heart rate and oxygen uptake were measured. From the tests heart rate and energy cost were interpolated for power outputs of 100, 150, 200, 250, and 300W. When compared with pedal rate, both heart rate and energy cost varied as a quadratic function at a given power output. The low point in the curve was used as the optimal pedal rate. When plotted against power output, optimal pedal rate varied linearly, i.e. as power output increased, so did optimal pedal rate. The second experiment consisted of five 30-min tests at about 85% of the subjects' maximum. The same pedal rates were used. In this experiment, energy cost, heart rate, perceived exertion, blood lactate concentration, and plasma levels of epinephrine, norepinephrine, and B-endorphin were measured. When compared across pedal rates, energy cost, heart rate, and perceived exertion all were minimal at 80 RPM at each sampling period. Blood lactate showed the same relationship with pedal rate as the preceding variables at 10-min of exercise, but not late in the test. The catecholamine values appeared to follow the same trend but not significantly. B-endorphin showed no differences.

The two experiments show that in this group of cyclists an optimal pedal rate exists, and that it shows up in measures of both stress and efficiency. It also shows that the most efficient pedal rate changes with power output. These experiments indicate that the choice of pedal rate is an important one for both researchers and bicyclists who use high power outputs. They also indicate that a need exists for a more individual type of testing for different types of subjects.

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