Gender Differences in Substrate Metabolism During Endurance Exercise

Females show a lower respiratory exchange ratio (RER) than males during submaximal endurance exercise, which translates into a proportionately lower carbohydrate and higher fat oxidation. Data from rodents show that 17-beta-estradiol may mediate these metabolic differences. 17-beta-estradiol supplementation in humans is less convincing; however, two studies found a reduction in glucose rate of appearance during exercise. No difference is found …