Hit Effects On Substrates Oxidation Rates Of Women In Different Phases Of Monthly Ovarian Cycle

Abstract

The metabolic inflexibility (limitation to respond or adapt to conditional changes in metabolic demand due to dietary patterns, energy availability, or circulating energy substrates) may be associated with variations in estrogen concentrations observed during the monthly ovarian cycle, whereas that apparently healthy women of childbearing age exhibit variation in substrates oxidation rates that may lead to overweight, type II diabetes and other associated conditions. PURPOSE: The aims of this study were to verify and compare the influence of eight treadmill high-intensity interval training (HIT) sessions on carbohydrate and lipid oxidation rates (CHOox and LIPox, respectively) and intensities of ventilatory anaerobic thresholds (VATs) of women in different phases of monthly ovarian cycle. METHODS: Eleven irregularly active women performed incremental treadmill exercise testing followed by submaximal work-rate running for 45min to determine VATs, VO2peak, peak velocity (Vpeak), and substrate oxidation rates, before and after training period, in different phases of their monthly ovarian cycle (“Follicular” phase group, FPG, n=6; “Luteal” phase group, LPG, n=5). The training period consisted of eight HIT sessions, composed each one of eight sets of 60s running at 100%Vpeak interspersed by 75s recovery, every 48h. RESULTS: Our results showed no significant differences in VATs intensities between groups. The comparison between groups showed significant differences in relative energy derived from CHOox pre-post training of the -61.4% and -59.3% respectively, and LIPox pre-post training of the 27.5% and 34.4% respectively. The relative energy derived from CHOox after the training period were 18.9% and 25.5% higher to FPG and LPG, respectively; consequently, the relative energy derived from LIPox after the training period were 8,45% and 3.46% lower to FPG and LPG, respectively. Over the training period, Vpeak was ~13.5 km/h, which produced the relative intensities of ~89%VO2peak e ~93%HRpeak for both groups. CONCLUSION: The monthly ovarian cycle phases promote significant changes on substrates oxidation rates leading to decrease of CHOox. High intensity interval training can minimize the differences observed and constitute an alternative intervention.