INCREMENTAL EXERCISE RESPONSES FOR FEMALES DURING THREE DIFFERENT PHASES OF THE MENSTRUAL CYCLE

Abstract

PURPOSE Previous research has indicated metabolic differences between the follicular and luteal phases of the menstrual cycle which could affect performance. This study analyzed exercise performance during menses (M), during mid-follicular (F) phase and during mid-luteal phase (L) for 16 females (ages 21–43) with normal menstrual cycles. METHODS The 9 untrained and 7 aerobically conditioned athletes participated in an incremental exercise protocol during each phase of their cycle (in random order) to fatigue on the cycle ergometer. RESULTS Pre test dietary intake was monitored and the percentage of carbohydrates in pretest meals were identical (M=52.3, F=52.6, L=52.5) for the three trials. Body weight was significantly greater during M (61.9 kg) than during the F phase (61.3 kg), but not the L phase (61.5 kg). Performance time to fatigue tended to be greater (p = .07) during the L phase (14.81 min) compared to the F phase (14.13 min), but not different than the M trial (14.27 min). Interestingly, the trained subjects fatigued equally during M (16.88 min) and the L phase (16.82 min), while the untrained exercised significantly (p = .03) longer during the L phase (13.01 min) then during M (11.36 min). No significant differences were found in lactate, RPE, or heart rate; however, at the third workload, RPE tended to be higher (p = .06) during F phase (13.3) than during M (12.7), while heart rates were identical (163.7 bpm). CONCLUSIONS This research suggests that for trained athletes there is no decrement of performance if performing during menses; however, for all subjects, an increase in body weight is experienced during M which could potentially reduce endurance performance.