Purpose: The purpose of this study was to investigate the effect of menstrual cycle on performance, lipid peroxidation, and muscle damage after exhaustive exercise. Methods: Nine females with regular menstrual cycle participated in this research. The subjects preformed the incremental bicycle ergometer test until exhaustion at a constant pedal speed of 60 rpm with stepwise increment of 15W every minute after a warm-up at 15W for 3 min in mid follicular (MF) and mid luteal (ML) of menstrual cycle. Serum creatine kinase (CK), malondialdehyde (MDA), and superoxide dismutase (SOD) in the erythrocytes were measured before, immediately after and 24h after exercise. The VO2max, hart rate (HR), lactic acidosis (LA), and total exercise time were also recorded. Results: The levels of the CK and SOD were not significant changes before, immediately after and 24h after exercise during each phase of the menstrual cycle (p > .05). However, the level of the MDA was significantly different between follicular phase and luteal phases of the menstrual cycle (12.01 ± 3.01 vs. 6.92 ± 3.05 nmol/ml, p < .05), and it did not show a significant change after exercise during each phase of the menstrual cycle (p > .05) via ANCOVA analysis. The VO2max, HR and LA were not changed but the exhaustion time between the mid-follicular phase and the mid-luteal phase (659.2 ± 101.7 vs. 690.7 ± 89.42 s, p < .05). Conclusion: The findings of this study suggest that females may perform longer time before exhaustion, which may be due to a lower oxidative stress in mid luteal phase of menstrual cycle, but no different effects on oxidative stress and muscle damage in between were found.
Purpose: The purpose of this study was to investigate the effect of menstrual cycle on performance, lipid peroxidation, and muscle damage after exhaustive exercise. Methods: Nine females with regular menstrual cycle participated in this research. The subjects preformed the incremental bicycle ergometer test until exhaustion at a constant pedal speed of 60 rpm with stepwise increment of 15W every minute after a warm-up at 15W for 3 min in mid follicular (MF) and mid luteal (ML) of menstrual cycle. Serum creatine kinase (CK), malondialdehyde (MDA), and superoxide dismutase (SOD) in the erythrocytes were measured before, immediately after and 24h after exercise. The VO2max, hart rate (HR), lactic acidosis (LA), and total exercise time were also recorded. Results: The levels of the CK and SOD were not significant changes before, immediately after and 24h after exercise during each phase of the menstrual cycle (p > .05). However, the level of the MDA was significantly different between follicular phase and luteal phases of the menstrual cycle (12.01 ± 3.01 vs. 6.92 ± 3.05 nmol/ml, p < .05), and it did not show a significant change after exercise during each phase of the menstrual cycle (p > .05) via ANCOVA analysis. The VO2max, HR and LA were not changed but the exhaustion time between the mid-follicular phase and the mid-luteal phase (659.2 ± 101.7 vs. 690.7 ± 89.42 s, p < .05). Conclusion: The findings of this study suggest that females may perform longer time before exhaustion, which may be due to a lower oxidative stress in mid luteal phase of menstrual cycle, but no different effects on oxidative stress and muscle damage in between were found.