| Summary: | 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. === Education, Faculty of === Kinesiology, School of === Graduate
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