Does the Menstrual Cycle Influence Aerobic Capacity in Endurance-Trained Women?

Purpose: The aim was to study if aerobic capacity varies during different phases of the menstrual cycle (MC) in endurance-trained female athletes. Methods: Ten endurance-trained eumenorrheic women performed a submaximal test followed by an incremental test until exhaustion three times during one MC, early follicular phase (EFP), late follicular phase (LFP), and midluteal phase (MLP). During the submaximal test, the respiratory exchange ratio (RER) and utilization of fat and carbohydrates were analyzed; and, during the incremental test, VO2 peak, maximal heart rate, utilization of fat and carbohydrates, and RER were analyzed. Lactate levels were analyzed at rest, during the submaximal test, and after the incremental test. The anaerobic threshold was determined at RER = 1. Results: No significant differences (p < .05) between the MC phases were seen in a maximal heart rate or VO2peak. Similarly, VO2, heart rate, RER, fatty acid oxidation, and carbohydrate oxidation at 70, 80, 90, and 100% of VO2peak did not differ significantly between MC phases. There were no significant differences between these phases in resting lactate before the test or during the submaximal tests, though there was a significant difference in lactate concentration 3 minutes after the incremental test between the EFP and the LFP (p = .043). Conclusion: This study did not display variations in physiological parameters between EFP, LFP, and MLP, indicating similar aerobic capacity despite hormonal variations. This knowledge may be useful when planning for competition in aerobic events.

Effects on power, strength and lean body mass of menstrual/oral contraceptive cycle based resistance training.

BACKGROUND: The purpose of this study was to investigate the effects of menstrual and oral contraceptive cycle on a high frequency periodized leg resistance training in trained women. METHODS: Two groups performed high frequency leg resistance training for two weeks of each menstrual/oral contraceptive cycle for four months. The remaining part of the cycle they performed the leg training once a week. Group 1 (N.=19) trained with high frequency (5 times∙w-1) during the first two weeks of each cycle, and group 2 (N.=19) during the last two weeks of each cycle. A control group (N.=21) performed regurlar (3 times∙w-1) leg resistance training for four months. RESULTS: Significant increase in squat and countermovement jump, and peak torque values in hamstrings for group 1 were observed, but not in group 2. In the control group an increase in squat and countermovement jump, and peak torque (only left hamstring) was also observed. There was also a significant increase in lean body mass of the legs in group 1 only. There were no evident differences in the training effects between women with or without oral contraceptive. CONCLUSIONS: The high frequency periodized leg resistance training during the first two weeks of the menstrual cycle is more beneficial to optimize training than in the last two weeks. Resistance training during the first two weeks of the menstrual cycle even resulted in a larger gain of lean body mass than regular training.

Increasing training load without risking the female athlete triad: menstrual cycle based periodized training may be an answer?

BACKGROUND: An improved muscle strength are of great importance in many sports, hence an increased understanding on how to generate optimal strength training programs in women without negative side effects that may lead to the female athlete triad are essential. The purpose of this study was to investigate potential negative effects of high frequency periodized menstrual/oral contraceptives (OC) cycle based leg resistance training on components in the female athlete triad. METHODS: Fifty-nine women, with experience of resistance training and with regular menstrual/OC cycles were included in the analyses. The participants were randomly assigned a training program consisted of high frequency leg resistance training, periodized to the first two weeks (group 1) or the last two weeks (group 2) of each cycle, or to a control group performing regular training, during four consecutive menstrual/OC cycles. The main analysis was the pre-to-post change of sex and growth hormones, cortisol, total body fat mass, bone mineral density in the spine. We further examined the participants' own experience of the training programs. RESULTS: No significant negative impact on sex and growth hormones, cortisol, total body fat mass and bone mineral density in the spine, was detected in any of the groups. Moreover, the women in group 1 experienced their training program as positive. CONCLUSIONS: The high frequency periodized leg resistance training was not associated with exercise-related negative consequences on components in the female athlete triad. Moreover, the training was well accepted when performed during the first two weeks of each cycle.