Does menstrual cycle phase affect exercise performance? Original paper

Hormonal fluctuations during the menstrual cycle may affect exercise performance. Progesterone, which increases during the mid-luteal (ML) phase, is associated with increased heart rate, minute ventilation, and core body temperature. The ML phase is often associated with a more negative mood state, potentially affecting fatigue and the motivation to engage in exercise. However, research assessing differences in performance based on menstrual cycle phase is limited.

This study assessed the effects of the menstrual cycle phase (ML vs. the mid-follicular (MF) phase) on aerobic exercise performance. Twelve recreationally-active eumenorrheic women (women with normal periods) completed exercise sessions during the MF and the ML phases. The investigators assessed the serum concentrations of progesterone and estradiol, measured basal body temperature, and used ovulation kits to assess the menstrual cycle phase. Each session consisted of two 5-minute cycling sessions at two different intensities (10% below and 10% above the gas exchange threshold), followed by an 8-kilometer cycling time trial. Heart rate, ventilation, oxygen uptake, rating of perceived exertion (RPE), and fatigue were assessed throughout each exercise session. Total mood disturbance was assessed before and 20 minutes after exercise.

Minute ventilation, VO₂max, and ratings of fatigue were higher during the ML than in the MF phase when cycling at 10% below the gas exchange threshold, with no differences when cycling at 10% above the gas exchange threshold. During the time trial, the mean power output was lower, the completion time was longer, and the ratings of fatigue were higher during the ML than the MF phase. Total mood disturbance was greater before exercise during ML than MF, with no differences between phases after exercise. Heart rate, RPE, minute ventilation, and oxygen uptake during the time trial did not differ between phases.

The gas exchange threshold utilized in the current study is defined as the intensity at which lactate increases and bicarbonate is reduced in the blood, causing a greater increase in production of CO₂ relative to uptake of O₂.^[1]