Hypothalamic-pituitary-gonadal (HPG) axis suppression in exercising women can be caused by low energy availability (EA) but the impact of a real-world, multi-stressor training environment on reproductive and metabolic function is unknown. This study aimed to characterize reproductive and metabolic adaptation in women undertaking basic military training. Design: Prospective cohort study in women undertaking 11-month initial military training (n=47). Dynamic low dose 1-hour GnRH tests were completed after 0 and 7 months of training. Urine progesterone was sampled weekly throughout. Body composition (dual x-ray absorptiometry), fasting insulin resistance (homeostatic modelling assessment 2, HOMA2), leptin, sex steroids, AMH and inhibin B were measured after 0, 7 and 11 months with an additional assessment of body composition at 3 months. Results: LH and FSH responses were suppressed after 7 months (both p<0.001). Among non-contraceptive users (n=20), 65% had regular (23-35d) cycles pre-enrolment, falling to 24% by 7 months of training. Of women in whom urine progesterone was measured (n=24), 87% of cycles showed no evidence of ovulation. There was little change in AMH, LH and estradiol, although inhibin B and FSH increased (p<0.05). Fat mass fluctuated during training but at month 11 was unchanged from baseline. Fat-free mass did not change. Visceral adiposity, HOMA2 and leptin increased (all p<0.001). Conclusions: HPG axis suppression with anovulation occurred in response to training without evidence of low EA. Increased insulin resistance may have contributed to the observed pituitary and ovarian dysfunction. Our findings are likely to represent an adaptive response of reproductive function to the multi-stressor nature of military training.

中文翻译：

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女性对多压力源训练的生殖和代谢适应

运动女性的下丘脑-垂体-性腺 (HPG) 轴抑制可能是由低能量可用性 (EA) 引起的，但现实世界的多压力源训练环境对生殖和代谢功能的影响尚不清楚。本研究旨在描述接受基础军事训练的女性的生殖和代谢适应特征。设计：对接受 11 个月初始军事训练的女性进行前瞻性队列研究 (n=47)。训练 0 个月和 7 个月后完成动态低剂量 1 小时 GnRH 测试。整个过程中每周对尿黄体酮进行取样。在 0、7 和 11 个月后测量身体成分（双 X 射线吸收测定法）、空腹胰岛素抵抗（稳态模型评估 2，HOMA2）、瘦素、性类固醇、AMH 和抑制素 B，并在 3 个月时对身体成分进行额外评估。结果：7 个月后 LH 和 FSH 反应受到抑制（均 p<0.001）。在非避孕使用者 (n=20) 中，65% 的人在注册前有定期（23-35 天）周期，经过 7 个月的培训后，这一比例降至 24%。在测量尿液黄体酮的女性中（n=24），87% 的周期没有显示排卵迹象。尽管抑制素 B 和 FSH 有所增加，但 AMH、LH 和雌二醇变化不大（p<0.05）。训练期间脂肪量有所波动，但在第 11 个月时与基线相比没有变化。无脂肪质量没有变化。内脏脂肪、HOMA2 和瘦素增加（全部 p<0.001）。结论：HPG 轴抑制伴随无排卵，是对训练的反应，但没有低 EA 的证据。胰岛素抵抗增加可能导致观察到的垂体和卵巢功能障碍。我们的研究结果可能代表了生殖功能对军事训练的多重压力性质的适应性反应。