Goldfarb A H, Jamurtas A Z, Kamimori G H, Hegde S, Otterstetter R, Brown D A
Exercise and Sport Science Department, University of North Carolina-Greensboro 27412, USA.
Med Sci Sports Exerc. 1998 Dec;30(12):1672-6. doi: 10.1097/00005768-199812000-00003.
Twelve healthy men (26.4 yr) and women (26.8 yr) were compared at rest and after cycling for 25 min at 60 and 80% VO2max to determine whether gender and menstrual cycle influenced circulating beta-endorphin concentration (BE).
VO2max was determined on a cycle ergometer, and subjects completed the exercise in a randomized order. Women were tested in both the luteal (L) and follicular (F) phases of their menstrual cycle, which was confirmed by their blood estrogen levels. All tests were conducted in the morning after a 30-min rest (12-h postabsorptive). An indwelling venous catheter placed in a forearm vein enabled blood sampling at rest, 25 min of cycling, and 25 min of recovery.
Resting BE was similar for men before both 60 and 80% intensities of exercise, 5.27 +/- 0.43 and 5.30 +/- 0.33 pmol.mL-1, respectively. BE was not significantly changed at 60% VO2max (6.54 +/- 0.33 pmol.mL-1) but significantly increased at 80% VO2max (11.90 +/- 1.98 pmol.mL-1). Women tended to have slightly lower BE during the L compared with F, but this did not reach significance (L = 4.40 +/- 0.22, F = 4.73 +/- 0.30 pmol.mL-1). Cycling at 60% VO2max did not significantly increase BE in the L (5.41 +/- 0.42 pmol.mL-1) nor the F (5.35 +/- 0.40 pmol.mL-1). Cycling at 80% VO2max increased BE to a similar extent in both the L and F phase, respectively (10.44 and 10.96). Although the BE concentrations tended to be slightly lower in women compared with men at 80% VO2max, this did not reach statistical significance.
These data suggest that women cycling at 80% VO2max will have a similar BE response to men independent of their menstrual cycle. BE in women at rest and who exercise at lower exercise intensities may have slightly lower BE levels then men independent of the time of the women's menstrual cycle.
比较12名健康男性（26.4岁）和女性（26.8岁）在静息状态以及以60%和80%最大摄氧量（VO₂max）进行25分钟骑行后的情况，以确定性别和月经周期是否会影响循环β-内啡肽浓度（BE）。
在功率自行车上测定VO₂max，受试者按随机顺序完成运动。女性在月经周期的黄体期（L）和卵泡期（F）进行测试，通过血液雌激素水平予以确认。所有测试均在早晨休息30分钟后（吸收后12小时）进行。在前臂静脉留置一根静脉导管，以便在静息状态、骑行25分钟以及恢复25分钟时采集血样。
在60%和80%运动强度之前，男性静息状态下的BE相似，分别为5.27±0.43和5.30±0.33皮摩尔/毫升。在60%VO₂max时BE无显著变化（6.54±0.33皮摩尔/毫升），但在80%VO₂max时显著升高（11.90±1.98皮摩尔/毫升）。与卵泡期相比，女性在黄体期的BE往往略低，但未达到显著差异（黄体期=4.40±0.22，卵泡期=4.73±0.30皮摩尔/毫升）。以60%VO₂max骑行在黄体期（5.41±0.42皮摩尔/毫升）和卵泡期（5.35±0.40皮摩尔/毫升）均未显著增加BE。以80%VO₂max骑行在黄体期和卵泡期使BE升高的幅度相似（分别为10.44和10.96）。尽管在80%VO₂max时女性的BE浓度往往略低于男性，但未达到统计学显著差异。
这些数据表明，以80%VO₂max骑行的女性，无论其月经周期如何，其BE反应与男性相似。静息状态及以较低运动强度运动的女性，其BE水平可能略低于男性，且与女性月经周期时间无关。
