B-61 Free Communication/Poster - Acute Exercise Wednesday, May 29, 2019, 1: 00 PM - 6: 00 PM Room: CC-Hall WA2
Influence of Menstrual Cycle Phase on Cardiovascular Drift and Maximal Oxygen Uptake During Heat Stress
983 Board #217 May 29 2:00 PM - 3:30 PM
Cardiovascular drift (CV drift) is related to reduced maximal oxygen uptake (V̇O2max) during heat stress. Whether this relationship is modified by elevated core temperature during the luteal phase (LP) of the menstrual cycle remains unknown.
PURPOSE: To test the hypothesis that the magnitude of CV drift and accompanying decrement in V̇O2max is greater during the LP of the menstrual cycle vs. the follicular phase (FP).
METHODS: Seven women (mean±SD; age=24±5 y) completed a graded exercise test in ~22 °C to determine V̇O2max, followed by one 15-min and one 45-min trial at 60% V̇O2max in 35 °C—each immediately followed by measurement of V̇O2max—in the FP and LP. CV drift was measured between 15 and 45 min during the 45-min trials. The purpose of the separate 15- and 45-min trials was to measure CV drift and V̇O2max over the same time interval.
RESULTS: Rectal temperature (Tre) at rest and during exercise was higher in the LP (p<0.05). Heart rate increased 9% between 15 and 45 min in both phases (p=0.71), while stroke volume decreased more in the LP (-18%) compared to the FP (-11%; p<0.001). V̇O2max decreased significantly over time (p=0.002), but menstrual cycle phases were not different (16% and 13% for LP and FP, respectively, p=0.28).
CONCLUSION: Greater thermal strain in the LP compared to the FP did not modulate the relationship between CV drift and V̇O2max during exercise in the heat.Copyright © 2019 by the American College of Sports Medicine