Degree Name

Master of Science (MS)

Semester of Degree Completion

1994

Thesis Director

Phyllis T. Croisant

Abstract

A plateau in oxygen consumption during exercise testing has been considered a requisite indicator of achievement of true maximal oxygen consumption. The wide range of reported percentages of subjects revealing a plateau (7 to 80 percent) indicates that closer analysis of factors that may influence plateau attainment is necessary. This study examined the frequency of plateau attainment in two groups of differentially trained subjects. One group (TR) of 12 males (ages 18-36) were trained runners and the other group (WL) of 12 males (ages 18-31) consisted of trained weight lifters. The subjects participated in a series of maximal exercise tests performed on a cycle ergometer equipped with toe straps.

Subjects first completed a continuous graded exercise test which started at a power output of 720 kgm/min and increased every two minutes until exhaustion. Subjects then completed a series of daily discontinuous supramaximal exercise tests, which consisted of maintaining a preset power output (beginning the a next higher power output than the highest power output obtained on the continuous test) for at least 90 seconds. The subsequent constant power outputs were increased until the subject could no longer perform the power output for at least 90 seconds. The pedal frequency was increased for the higher discontinuous power outputs.

The criteria for determination of a plateau was less than a 0.15 L/min increase in oxygen consumption between the peak VO2 obtained on a continuous test and the mean of the peak values obtained on each of the supramaximal discontinuous tests.

The results showed 92% (11) of trained runners and 83% (10) of trained weightlifters attained a plateau in oxygen consumption. The calculated Chi Square value was not statistically significant (p <.05). The results reveal a high percentage (88%) of subjects attaining a plateau in oxygen consumption with no significant difference between the differentially trained groups under the conditions studied.

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