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The menstrual cycle, ovulatory, and hormonal effects of an 8-week abruptly increasing running program in recreationally active women

University of British Columbia

Background: Researchers assert that a woman's reproductive system is disrupted below an energy availability (EA) threshold of 25kcal/kgLBM/day, independent of exercise stress. Alternatively, research also suggests that an abrupt increase in training over an 8-week period disrupts luteal and ovulatory function in recreationally active women. It is not known whether EA and/or the stress of an abrupt program will further disrupt the luteal, ovulatory, and hormone function in gynecological mature women with regularly ovulatory and disturbed menstrual cycles. Methods: The menstrual cycle, ovulatory, and hormonal characteristics in recreationally active and gynecologically mature women (19 +/- 0.8 years) were prospectively compared between a 2- menstrual cycle control phase and an 8-week abruptly increasing training phase. Women with normally ovulatory and menstrual cycle and ovulatory disturbances were included in this study. The twenty participants sustained no injuries, as the 8-week training program increased abruptly in volume and intensity by a mean rate of 19.5% per week. Initial aerobic capacity (37.6 +/- 3ml/kg/min) non-significantly increased by 2.3ml/kg/min (p = 0.086) and ventilatory threshold significantly increased by 2ml/kg/min (p = 0.021). Regardless of a significant decrease in EA by 4.8kcal/kgLBM/day, body weight and composition remained constant over the training phase. Results: The Menstrual Cycle Diaries© and Quantitative Basal Temperatures (QBT) method of least-squares analysis revealed no significant training differences in menstrual cycle, luteal phase, and follicular phase length, as well as, ovulation status, luteal phase index, and premenstrual symptoms. Competitive enzyme immunoassays (EIAs) technique revealed no statistical control-to-training-phase differences in early follicular phase pregnanediol-3- glucuronide (PdG), luteal phase PdG and estrone conjugates (E1C), and Cortisol. The control to training change in early follicular phase E1C did approach statistical significance (p = 0.0012) and the change in energy availability accounted for 23.1% of its variability (p = 0.044). Conclusions: Menstrual cycle and ovulatory characteristics in recreationally active women are robust to an 8-week abruptly increasing training program and a mean decrease in energy availability by 4.8kcal/kgLBM/day. However, a change in energy availability by 4.8kcal/kgLBM/day accounted for 23.1% of the variance in early follicular phase E1C change from the control menstrual cycle #2 to training menstrual cycle #2.

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2009-12-16

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http://hdl.handle.net/2429/16813

Human Kinetics

University of British Columbia

UBCV

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