Fatigue resistance is altered during the high-hormone phase of eumenorrheic females but not oral contraceptive users
Document Type
Journal Article
Publication Title
Medicine & Science in Sports & Exercise
Publisher
Wolters Kluwer
School
School of Medical and Health Sciences / Nutrition and Health Innovation Research Institute
RAS ID
60327
Funders
Edith Cowan University Nutrition and Health Innovation Research Institute / Royal Perth Hospital Research Foundation Fellowship / Emerging Leader Fellowship from Future Health Research and Innovation Fund
Abstract
Purpose: To examine the effect of ovarian hormones and their synthetic equivalents on substrate utilisation and fatigue resistance during a race-specific cycling protocol. Methods: 17 well-trained female cyclists (9 eumenorrheic females, 8 oral contraceptive users), completed two experimental trials, in a randomised order, in their low (follicular/sugar pill) and high-hormone (luteal/active pill) phases. Each 91-min trial consisted of a 45-min moderate-intensity component (SMC) followed by 6-min of high-intensity (HIT) and then a fatigue resistance test (FRT): 6x1-min all-out efforts with 1-min active recovery. Meals, comprising carbohydrate (CHO) intake of 8 g.kg-1 body mass, were standardised 24-h pre-trial. An electrolyte-only solution was provided ad-libitum during each trial. Results: In eumenorrheic females, a large reduction in average power during FRT was observed in the luteal phase (277 ± 31 vs. 287 ± 33 W; P = 0.032). Greater CHOox (~ 4 %, P = 0.020) during SMC and ventilatory inefficiencies during SMC and HIT (~ 7 %, P < 0.001) were also observed in the luteal phase. In OC users, despite some phasal changes in cardiorespiratory and metabolic data in SMC (~6% higher blood glucose and ~ 2% higher minute ventilation in active pill phase), none of the performance parameters in the FRT were different. Conclusions: Fatigue resistance was compromised only in high-hormone phase of the menstrual cycle, with eumenorrheic females likely susceptible due to increased CHO utilisation during SMC. Hormone-induced ventilatory inefficiencies may also have increased metabolic demand. These findings emphasise the need to maintain CHO availability for power production, particularly in high-hormone phases.
DOI
10.1249/MSS.0000000000003289
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Comments
Lee, S. J. L., Sim, M., Van Rens, F. E. C. A., & Peiffer, J. J. (2023). Fatigue resistance is altered during the high-hormone phase of eumenorrheic females but not oral contraceptive users. Medicine & Science in Sports & Exercise. Advance online publication. https://doi.org/10.1249/MSS.0000000000003289