Effects of Resistance Training on Substrate Metabolism During the Menstrual Cycle

Based on the literature the investigators hypothesize an increase in fat oxidation in early follicular phase(EFP) and late follicular phase (LFP) when compared to early luteal phase (ELP) and late luteal phase (LLP). Given the lack of research in exercise and menstrual cycle - especially in resistance training - results are uncertain unless the investigators base their hypotheses only on the general physiological effects of sex hormones (without exercise). In this case, the investigators expect to see a reduced carbohydrate utilization and an increased utilization of fats in EFP and LFP. In addition, the intervention is focused on muscular endurance and, therefore, it is expected to see a higher reliance on aerobic pathways. It is expected that the effects of the intervention will be added to the effects of estrogens, with increasing fat oxidation when estrogen levels are higher. Lastly, a comparison of fat oxidation levels obtained on each sub-phase would reveal if there are differences in the magnitude of the effect of distinct concentrations of estrogen and progesterone.