PURPOSE This study aimed to examine the effect of ovarian hormones and their synthetic equivalents on substrate utilization and fatigue resistance during a race-specific cycling protocol. METHODS Seventeen well-trained female cyclists (nine eumenorrheic females, eight oral contraceptive users) completed two experimental trials, in a randomized 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 (submaximal cycling, or SMC) followed by 6 min of high-intensity (HIT) and then a fatigue resistance test (FRT): 6 × 1-min all-out efforts with 1-min active recovery. Meals, comprising carbohydrate (CHO) intake of 8 g·kg -1 body mass, were standardized 24-h pretrial. 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 CHO ox (~ 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 contraceptive 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 because of increased CHO utilization during SMC. Hormone-induced ventilatory inefficiencies may also have increased metabolic demand. These findings emphasize the need to maintain CHO availability for power production, particularly in high-hormone phases.

中文翻译：

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正常月经女性的疲劳抵抗力在高激素阶段发生改变，但口服避孕药使用者则没有改变。


目的本研究旨在检查卵巢激素及其合成等效物在特定种族的骑行方案中对底物利用率和抗疲劳性的影响。方法 十七名训练有素的女性自行车手（九名月经正常的女性，八名口服避孕药使用者）以随机顺序完成了两项实验试验，分别处于低激素（卵泡/糖丸）和高激素（黄体/活性丸）阶段。每个 91 分钟的试验包括 45 分钟的中等强度部分（次最大循环，或 SMC），随后是 6 分钟的高强度 (HIT)，然后是抗疲劳测试 (FRT)：6 × 1 分钟全1 分钟积极恢复的努力。膳食，包括8 g·kg -1 体重的碳水化合物（CHO）摄入量，在试验前24小时进行标准化。在每次试验期间随意提供仅含电解质的溶液。结果 在月经正常的女性中，在黄体期观察到 FRT 期间平均功率大幅下降（277 ± 31 vs 287 ± 33 W；P = 0.032）。在黄体期还观察到 SMC 期间 CHO ox 较高（约 4%，P = 0.020）以及 SMC 和 HIT 期间通气效率低下（约 7%，P < 0.001）。在避孕药使用者中，尽管 SMC 中的心肺和代谢数据发生了一些阶段性变化（主动服药阶段血糖升高约 6%，每分钟通气量升高约 2%），但 FRT 中的性能参数均无差异。结论 疲劳抵抗力仅在月经周期的高激素阶段受到损害，月经正常的女性可能由于 SMC 期间 CHO 利用率增加而容易受影响。激素引起的通气效率低下也可能增加代谢需求。这些发现强调需要维持 CHO 的可用性以用于发电，特别是在高激素阶段。