Hormonal and metabolic responses to exercise across time of day and menstrual cycle phase

Abstract

Two studies, each utilizing short-term treadmill exercise of a different intensity, assessed the metabolic and hormonal responses of women to exercise in the morning (AM) and late afternoon (PM). In study 1, plasma concentrations of growth hormone, arginine vasopressin, catecholamines, adrenocorticotropic hormone, cortisol, lactate, and glucose were measured before, during, and after high-intensity exercise (90% maximal O2 uptake) in the AM and PM. In study 2, plasma concentrations of adrenocorticotropic hormone, cortisol, lactate, and glucose were measured before, during, and after moderate-intensity exercise (70% maximal O2 uptake) in the AM and PM in the follicular (days 3-9), midcycle (days 10-16), and luteal (days 18-26) phases of the menstrual cycle. The results of studies 1 and 2 revealed no significant diurnal differences in the magnitude of responses for any measured variable. In addition, study 2 revealed a significant time-by-phase interaction for glucose (P = 0. 014). However, net integrated responses were similar across cycle phases. These data suggest that metabolic and hormonal responses to short-term, high-intensity exercise can be assessed with equal reliability in the AM and PM and that there are subtle differences in blood glucose responses to moderate-intensity exercise across menstrual cycle phase.

No effect of menstrual cycle phase on glycerol or palmitate kinetics during 90 min of moderate exercise

“…Despite these differences, both studies are consistent in the observation of no significant effect of menstrual cycle phase on systemic glycerol and NEFA kinetics during exercise. Given the fact that estrogen and progesterone have been shown to significantly affect lipolysis and lipid metabolism in both animals and humans (7,9,11,18,19,33,34,36,37,39,43,46), present and previous data (8,25) suggest that the fluctuations (2,4,15,31,32,56) in estrogen and progesterone that cover the majority of the days in the normal menstrual cycle are of insufficient magnitude, and/or duration, to significantly affect resting or exercise lipid kinetics and whole body lipid oxidation. This does not rule out subtle differences that the current techniques are not sensitive enough to detect.…”

Effect of the menstrual cycle on performance of intermittent, high-intensity shuttle running in a hot environment

“…Previous studies examining glucose concentration, and oral contraceptive use have yielded equivocal findings with increases, decreases and no change in glucose concentrations being recorded (Bonen et al 1991;Kanaley et al 1992;Bemben 1993;Galliven et al 1997;Bailey et al 2000). These ambivalent findings might be related to the intensity and type of exercise, the type of oral contraceptive, the time during the contraceptive month and whether the subjects are fasted.…”

“…In moderate environmental conditions, for sub-maximal cycling and treadmill running, blood glucose was similar in the follicular and luteal phases (Bonen et al 1983;Kanaley et al 1992;Zderic et al 2001) whereas, for moderate intensity cycling and running, blood glucose has been shown to be lower (Lavoie et al 1987) or higher during the luteal phase (Galliven et al 1997;Zderic et al 2001). …”

Menstrual Cycle Effects on Perceived Exertion and Pain During Exercise Among Sedentary Women

“…Only one study used a sample of ''low to moderately'' trained participants, but this study still had only 9 particpants. 18 Further, although RPE is theoretically and empirically linked to HR among active individuals, sedentary and low-fit individuals have been shown to perceive greater exertion than HR measures indicate. 19,20 If RPE is indeed more indicative of the psychological response to exercise than physiological variables, larger sample sizes will be necessary to detect meaningful differences in psychological response across the cycle.…”