Fatigue resistance is altered during the high-hormone phase of eumenorrheic females but not oral contraceptive users
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.
Document Type
Journal Article
Date of Publication
2023
Volume
56
Issue
1
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
Copyright
subscription content
First Page
92
Last Page
102
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, 56(1), 92-102. https://doi.org/10.1249/MSS.0000000000003289