Degree Name

Master of Science (MS)

Semester of Degree Completion

1991

Thesis Director

John D. (Jake) Emmett

Abstract

The purpose of this study was to investigate the differences in physiological and subjective perceived exertion levels at maximal and submaximal treadmill exercise between three phases of the menstrual cycle in eumennorheic women.

Nine females of varying fitness levels were subjects in the study. None of the subjects were using oral contraception or hormone altering medications at the time of the study.

The subjects performed three separate maximal graded exercise tests (GXT) using the Balke protocol. During each GXT, oxygen uptake (VO2), heart rate (HR), blood pressure (BP), respiratory quotient (RQ), rate of perceived exertion, and total time to exhaustion were recorded. During an eight minute recovery period, RQ, HR, and BP were recorded. These GXTs were performed beginning with either onset of menses, at ovulation, (as determined by oral temperature), or at cycle end chosen in random order.

Group mean values for each menstrual cycle phase were calculated for VO2, HR, RQ, and time to exhaustion. Means were compared between the three phases using a multivariate analysis of variance for repeated measures with an alpha of 0.05. It was found that at 75% maximal exertion and at maximal exertion, the ovulation phase means tended to be highest for the parameters of VO2 (75% mean =26.662 ± 6.281 ml · kg-1· min-1, maximal mean = 35.32± 6.711 ml · kg-1· min-1), HR (75% mean - 153.25± 7.146 bpm, maximal mean = 175.75 ± 13.573 bpm), and time to exhaustion (15.205± 3.902 minutes). The lowest mean values for these same parameters were found at the menses phase at the 75% and maximal exertion levels of intensity (mean VO2 75% = 26.109 ± 5.063 ml·kg-1· min-1, mean VO2 max = 34.826 ± 6.799 ml·kg-1· min-1; mean HR at 75% = 152.625 ± 16.928 bpm, mean HR at maximal =171.25± 14.23 bpm; mean time to exhaustion = 14.845 ± 3.125 minutes). However, these differences were found not to be satistically significant (p=<0.05) between any of the menstrual phases.

It was concluded that the physiological responses which occur during submaximal and maximal exercise do not differ between menstrual cycle phases. However, trends were evident to indicate that ovulation produced the highest mean values for those parameters, and the menses phase produced the lowest. Further investigation of these trends is recommended.

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