Influence of the menstrual cycle on muscle glycogen repletion after exhaustive exercise in eumenorrheic women. J Strength Cond Res 37(4): e273-e279, 2023-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 6 1.3 years, height: 161.1 6 4.8 cm, and body mass: 55.5 6 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 13 C-magnetic resonance spectroscopy, and estradiol, progesterone, blood glucose, blood lactate, free fatty acid (FFA), and insulin concentrations were measured at t 5 0, 120, and 300 minutes postexercise. During the 5-hour recovery period, subjects consumed 1.2g•(kg body mass) 21 •h 21 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 the menstrual cycle phases (p 5 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 5 0.17; FFA, p 5 0.50; insulin, p 5 0.31; exercise time, p 5 0.67). In conclusion, the menstrual cycle did not influence muscle glycogen repletion after exercise.