Aerobic Exercise Performance is Impaired in Naturally Menstruating Females Compared with Males 24 Hours Following a Strenuous Aerobic Interval Workout

PURPOSE: To examine potential sex differences in recovery following strenuous aerobic exercise and to assess associations between recovery and symptoms in female exercisers. METHODS: Nine recreationally active/trained males (peak aerobic power [PeakAP] = 4.4 [0.7] W/kg) and 11 females (PeakAP = 4.3 [0.5] W/kg) completed an 8-km cycling time trial (8 kmTT) followed by a time to exhaustion (TTE) glycogen-depletion workout with 2-minute intervals at 90%, 80%, and 70% PeakAP separated by 2-minutes recovery at 50% PeakAP on 3 occasions. Recovery was quantified as finishing time of an 8 kmTT performed 24 hours following each session, adjusted for day 1. Females completed a Menstrual Symptom Index assessing the frequency and severity of 18 commonly experienced symptoms preexercise and postexercise. RESULTS: After adjusting for day 1, a main effect (P = .024) was observed with females completing the 8 kmTT 18 seconds (3-33 s) slower than males on day 2. Between-sex differences were not observed during the total TTE (P = .990), TTE at 70% PeakAP (P = .571), or 80% PeakAP (P = .421). However, males exhibited a superior TTE at 90% PeakAP, (P = .018). Menstrual Symptom Index scores preexercise (r = .77 [.32-.94], P = .005) and postexercise (r = .66 [.11-.90], P = .026) were associated with 8 kmTT recovery. CONCLUSION: Female exercisers may experience a differential recovery compared with males 24 hours after a strenuous bout of aerobic exercise. Such differences may be related to menstrual symptom burden.