Influence of the Menstrual Cycle on Muscle Glycogen Repletion After Exhaustive Exercise in Eumenorrheic Women

The purpose of this study was to investigate the effect of the menstrual cycle on muscle glycogen repletion postexercise. Eleven women with regular menstrual cycles (age: 20.2 +/- 1.3 years, height: 161.1 +/- 4.8 cm, and body mass: 55.5 +/- 5.7 kg) were assessed in 3 phases of the cycle: the early follicular phase (E-FP), late follicular phase (L-FP), and luteal phase (LP). Each test day began with glycogen-depleting exercise, followed by 5 hours of recovery. Muscle glycogen concentrations, using C-13-magnetic resonance spectroscopy, and estradiol, progesterone, blood glucose, blood lactate, free fatty acid (FFA), and insulin concentrations were measured at t = 0, 120, and 300 minutes postexercise. During the 5-hour recovery period, subjects consumed 1.2g.(kg body mass)(-1).h(-1) of carbohydrates every 30 minutes. The muscle glycogen concentrations increased at t 5 120 and t 5 300 minutes postexercise (p < 0.01) but were not significantly different between themenstrual cycle phases (p=0.30). Blood lactate concentrations were significantly higher in the L-FP and LP than in the E-FP (p < 0.05). Nonetheless, the blood glucose, FFA, insulin concentrations, and the exercise time until exhaustion in the E-FP, L-FP, and LP were similar (blood glucose, p=0.17; FFA, p=0.50; insulin, p=0.31; exercise time, p=0.67). In conclusion, the menstrual cycle did not influence muscle glycogen repletion after exercise.