Effect of menstrual cycle and gender on ventilatory and heart rate responses at the onset of exercise

Abstract

To clarify the luteal-follicular and male–female differences in ventilatory and heart rate responses at the onset of exercise, seven women and seven men performed voluntary exercise and passive movement for 20 s (brief voluntary exercise and brief passive movement) and voluntary exercise for 3 min (long voluntary exercise) in a sitting position. Voluntary exercise consisted of alternate flexion-extensions of both lower legs with a weight corresponding to about 2.5% of the subjects' body mass attached to each ankle, at a frequency of about 60 times min⁻¹. Passive movement was carried out without weights by experimenters pulling ropes attached to both of the subjects' ankles, in the same way as voluntary exercise. During these exercises and movements, minute inspiratory ventilation (V̇ _I) and heart rate (HR) were continuously measured by breath-by-breath and beat-to-beat techniques. We calculated relative changes of V̇ _I and HR (ΔV̇ _I and ΔHR). Additionally, we averaged ΔV̇ _I and ΔHR obtained during the exercise and movement for each subject, and performed a correlation analysis between the averaged ΔV̇ _I and ΔHR. It was clarified that: (1) ΔV̇ _I and ΔHR in the follicular phase were almost equal to those in the luteal phase; (2) there were no significant male–female differences in these parameters; (3) significant positive correlations were found in both genders only during brief voluntary exercise. We conclude that ventilatory and HR responses at the onset of voluntary exercise and passive movement are not affected by the menstrual cycle or gender.