Cardiorespiratory Variables During A Maximal Running Test In Well-trained Females With Different Hormonal Profiles

Abstract

Differences in estrogen and progesterone levels along a natural menstrual cycle and an oral contraceptive (OC) cycle may influence female´s performance. Previous literature reported lower strength, maximal oxygen consumption (VO2 max) and systolic volume in OC users. According to postmenopausal women, their low and stable levels of sex hormones may affect them in a different way than in young women. PURPOSE: To elucidate the effect of different hormonal profiles on maximal VO2, heart rate (HR) and ventilation (VE) in well-trained females. METHODS: Thirty-three eumenorrheic females (30.1±6.2 years, 59.3±8.4 kg, and 164.1±6.3 cm), twenty-three monophasic OC users (24.8±4.3 years, 58.6±5.8 kg, and 163.3±5.1 cm) and thirteen postmenopausal women (51.0±3.7 years, 54.9±4.1 kg, and 161.5±5.4 cm) participated in the study. A maximal graded test with a computerized treadmill was performed. Expired gases were measured breath-by-breath with the gas analyser Jaeger Oxygen Pro. HR was continuously monitored with a 12-lead ECG. Participants began with a warm-up of 3 minutes at 6 km/h. Then, the speed was set at 8 km/h, increasing 0.2 km/h every 12 seconds until exhaustion. RESULTS: One way ANOVA reported lower values in post-menopausal females compared to the other two groups (eumenorrheic and OC users) for all variables measured: VO2 max (2924.2±389.7 ml/min for the eumenorrheic; 2808.8±366.7 ml/min for the OC; and 2455.15±281.04 ml/min for the postmenopausal; p=0.001), maximal HR (184.2±10.3; 189.9±8.4; and 172.1±12.9 bpm respectively; p<0.001) and maximal VE (111.8±17.5; 114.7±15.1; and 96.4±10.4 l/min, respectively; p=0.003). Nonetheless, no significant differences in VO2max, HR and VE were found between eumenorrheic females and OC users. CONCLUSION: The drastic decrease of sex hormones in postmenopausal females, along with other hormonal and physiological changes caused by the age, may explain the drop in VO2 max, HR and VE in this population. In terms of young women, despite literature reported lower values in OC users, the lack of difference observed in this study may be due to the lower concentrations of sex hormones that OC pills have nowadays, or because of the fact that all were well-trained participants. Funding: DEP2016-75387-P (Spanish National Plan 2013-2016)