Abstract
This study examined the effect of estradiol- -17 across the menstrual cycle (MC) during aero- bic exercise on energy substrate utilization and oxidation. Thirty-two eumenorrheic (age = 22.4 3.8 y (mean SD)), physically active women participated in two steady-state running sessions at 65% of VO 2max, one during the early follicular and one during the luteal phase of the MC. Blood samples were collected at rest before each exercise session and analyzed for Estradiol- -17 to confirm the MC phase. Carbohydrate (CHO) utilization and oxidation values were significantly lower (p< 0.05) in the luteal (utilization: 51.6 16.7%; oxidation: 1.22 0.56 g/min; effect size (ES) = 0.45, 0.27) than follicular phase (utilization: 58.2 15.1%; oxidation: 1.38 0.60 g/min) exercise sessions. Conversely, fat uti- lization and oxidation values were significantly (p< 0.05) higher in the luteal (utilization:48.4 16.7% ; oxidation: 0.49 0.19 g/min; ES = 0.45,0.28) than follicular phase (utilization: 41.8 15.1%; oxidation: 0.41 0.14 g/min). Estradiol- -17 concentrations were significantly (p< 0.01) greater during the luteal (518.5 285.4 pmol/L; ES = 0.75) than follicular phase (243.8 143.2 pmol/L). Results suggest a greater use of fat and reduced amount of CHO usage during the luteal versus follicular phase, directly related to the change in resting estradiol- -17. Future research should investigate the role these changes may play in female athletic performance.
Description
This study investigates estradiol- -17's effect on energy substrate utilization during aerobic exercise in women.