The relationship between exercise-induced oxidative stress and the menstrual cycle.

The purpose of this study was to investigate the relationship between exercise-induced oxidative stress and the menstrual cycle in healthy sedentary woman. Eighteen women with regular menstrual cycles participated in this research. The subjects monitored their basal body temperature (BBT) and carried out a urinary ovulation test (twice) for 2 months prior to the study to determine their menstrual cycle. The subjects performed bicycle ergometer exercise (for 30 min at 60% V(.)>O(2max)) in each phase (menses, follicular and luteal phases) of the menstrual cycle. Serum estradiol and progesterone concentrations were determined from blood that was collected at rest. Serum thiobarbituric acid reactive substances (TBARS), total superoxide dismutase (T-SOD) and extracellular superoxide dismutase (EC-SOD) were determined as markers of oxidative stress in blood samples collected at rest and after exercise. TBARS was significantly lower after exercise [2.4 (0.5) nmol/ml] in the follicular phase, and T-SOD was significantly lower after exercise [3.2 (1.2) U/ml] in the luteal phase. EC-SOD did not show a significant change after exercise during each phase of the menstrual cycle. Furthermore, there was a negative correlation between estradiol and DeltaT-SOD ( r=-0.46, P<0.05) and between estradiol and DeltaEC-SOD ( r=-0.55, P<0.05) during the menses. All data are presented as the mean value and its standard deviation. The results of this study suggest that when the estradiol level is high in a menstrual cycle, free radicals produced as a consequence of exercise may be easily eliminated by sedentary women with normal menstrual cycles.