Loucks A B, Verdun M, Heath E M
Department of Biological Sciences and College of Osteopathic Medicine, Ohio University, Athens 45701-2979, USA.
J Appl Physiol (1985). 1998 Jan;84(1):37-46. doi: 10.1152/jappl.1998.84.1.37.
We tested two hypotheses about the disruption of luteinizing hormone (LH) pulsatility in exercising women by assaying LH in blood samples drawn at 10-min intervals over 24 h from nine young, habitually sedentary, regularly menstruating women on days 8, 9, or 10 of two menstrual cycles after 4 days of intense exercise [E = 30 kcal.kg lean body mass (LBM)-1.day-1 at 70% of aerobic capacity]. To test the hypothesis that LH pulsatility is disrupted by low energy availability, we controlled the subjects' dietary energy intakes (I) to set their energy availabilities (A = I - E) at 45 and 10 kcal.kg LBM-1.day-1 during the two trials. To test the hypothesis that LH pulsatility is disrupted by the stress of exercise, we compared the resulting LH pulsatilities to those previously reported in women with similar controlled energy availability who had not exercised. In the exercising women, low energy availability reduced LH pulse frequency by 10% (P < 0.01) during the waking hours and increased LH pulse amplitude by 36% (P = 0.05) during waking and sleeping hours, but this reduction in LH pulse frequency was blunted by 60% (P = 0.03) compared with that in the previously studied nonexercising women whose low energy availability was caused by dietary restriction. The stress of exercise neither reduced LH pulse frequency nor increased LH pulse amplitude (all P > 0.4). During exercise, the proportion of energy derived from carbohydrate oxidation was reduced from 73% while A = 45 kcal.kg LBM-1.day-1 to 49% while A = 10 kcal.kg LBM-1.day-1 (P < 0.0001). These results contradict the hypothesis that LH pulsatility is disrupted by exercise stress and suggest that LH pulsatility in women depends on energy availability.
我们通过对9名年轻、习惯久坐、月经规律的女性进行测试，以验证关于运动女性促黄体生成素（LH）脉冲性中断的两种假设。在两个月经周期的第8、9或10天，让她们进行4天的高强度运动[运动强度为30千卡·千克去脂体重（LBM）-1·天-1，为有氧能力的70%]，之后每隔10分钟采集一次血样，检测LH水平。为了验证LH脉冲性因能量可利用性低而中断的假设，我们在两项试验中控制受试者的膳食能量摄入量（I），使她们的能量可利用量（A = I - E）分别为45和10千卡·千克LBM-1·天-1。为了验证LH脉冲性因运动应激而中断的假设，我们将所得的LH脉冲性与之前报道的能量可利用性得到类似控制但未运动的女性的LH脉冲性进行比较。在运动女性中，能量可利用性低使清醒时间的LH脉冲频率降低了10%（P < 0.01），清醒和睡眠时间的LH脉冲幅度增加了36%（P = 0.05），但与之前研究中因饮食限制导致能量可利用性低的未运动女性相比，这种LH脉冲频率的降低幅度减弱了60%（P = 0.03）。运动应激既未降低LH脉冲频率，也未增加LH脉冲幅度（所有P > 0.4）。在运动期间，碳水化合物氧化所提供能量的比例从能量可利用量A = 45千卡·千克LBM-1·天-1时的73%降至A = 10千卡·千克LBM-1·天-1时的49%（P < 0.0001）。这些结果与LH脉冲性因运动应激而中断的假设相矛盾，表明女性的LH脉冲性取决于能量可利用性。
