Menstrual cycle phase dissociation of blood glucose homeostasis during exercise

Abstract

The purpose of this investigation was to evaluate the effects of 24-h carbohydrate-poor diet on metabolic and hormonal responses induced by prolonged exercise in both follicular (FP) and luteal (LP) phases of the menstrual cycle. At mid-FP and at mid-LP, seven eumenorrheic young women [means +/- SE; chronological age, 21.1 +/- 0.6 yr; O2 uptake (VO2) peak, 43.7 +/- 2.0 ml X kg-1 X min-1; body fat, 19.2 +/- 2.0%] were subjected to a 90-min bicycle exercise period at an intensity representing 63% of their measured VO2 peak. Venous blood samples obtained before and during exercise were analyzed for levels of substrates (glucose, lactate, free fatty acids, glycerol) and hormones (luteinizing hormone, progesterone, estradiol, insulin, glucagon, cortisol, catecholamines). Contrary to FP, a significant (P less than 0.01) decrease in blood glucose concentration was observed after 70 and 90 min of exercise during LP. Significant phase differences were also observed for blood lactate (highest in FP), cortisol (highest in LP), and progesterone (highest in LP). Although not significantly different, tendencies for menstrual phase dissociations were noticed for some of the other measured variables. Hence, a menstrual phase dissociation in circulating glucose level, unmasked by a prolonged exercise performed after a 24-h carbohydrate-poor diet, suggests to the authors a specific metabolic involvement for gonadotrophic and/or gonadal hormones.

No effect of menstrual cycle phase on glucose kinetics and fuel oxidation during moderate-intensity exercise

“…We also observed no significant mean differences in resting concentrations of insulin, epinephrine, norepinephrine, and cortisol, as others have reported (3,7,16,28,34,57). Changes in estrogen and progesterone across the normal menstrual cycle do not appear to be of sufficient magnitude to significantly affect resting substrate oxidation or glucose flux, as observed in the current study and by others (7,57).…”

“…Contrary to what was hypothesized, we observed no difference in whole body carbohydrate or lipid oxidation during moderate, prolonged exercise in the EF, MF, or ML phases. In addition, there were no differences in plasma glucose kinetics across cycle phases, despite a greater exercise increase in glucose and insulin concentrations in the luteal compared with both follicular phases.The present data agree with previous studies that show no effect of the menstrual cycle on resting whole body substrate oxidation (3,7,33) and resting concentrations of glucose, FFA, glycerol, and lactate (3,7,16,27,34). We also observed no significant mean differences in resting concentrations of insulin, epinephrine, norepinephrine, and cortisol, as others have reported (3,7,16,28,34,57).…”

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

“…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. When the metabolic contribution required from gluconeogenesis is high there tends to be a higher glucose concentration for oral contraceptive users during the contraceptive free week or when compared to eumennorheic women (Lavoie et al 1987;Bonen et al 1991;Bemben 1993). During prolonged exercise, blood glucose is initially supplied from the breakdown of glycogen and as exercise progresses gluconeogenesis becomes more crucial.…”

“…Thus, the lower glucose concentration during days 15-28 may be related to the higher exogenous ovarian hormones that may impair hepatic gluconeogenesis (Lavoie et al 1987). The lower glucose response could also be due to a decrease in hepatic glucose output or an enhanced glucose uptake, utilisation and glycogen storage that has been shown with estrogen treatment in animals (Bemben 1993).…”

“…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). …”