热暴露和重复运动对循环应激激素的影响。
The impact of heat exposure and repeated exercise on circulating stress hormones.
作者信息
Brenner I K, Zamecnik J, Shek P N, Shephard R J
机构信息
Graduate Department of Community Health, University of Toronto, Ontario, Canada.
出版信息
Eur J Appl Physiol Occup Physiol. 1997;76(5):445-54. doi: 10.1007/s004210050274.
To determine if heat exposure alters the hormonal responses to moderate, repeated exercise, 11 healthy male subjects [age = 27.1 (3.0) years; maximal oxygen consumption, VO2max = 47.6 (6.2) ml x kg x min(-1); mean (SD)] were assigned to four different experimental conditions according to a randomized-block design. While in a thermoneutral (23 degrees C) or heated (40 degrees C, 30% relative humidity) climatic chamber, subjects performed either cycle ergometer exercise (two 30-min bouts at approximately 50% VO2max, separated by a 45-min recovery interval, CEx and HEx conditions), or remained seated for 3 h (CS and HS conditions). Blood samples were analyzed for various exercise stress hormones [epinephrine (E), norepinephrine (NE), dopamine, cortisol and human growth hormone (hGH)]. Passive heating did not alter the concentrations of any of these hormones significantly. During both environmental conditions, exercise induced significant (P < 0.001) elevations in plasma E, NE and hGH levels. At 23 degrees C during bout 1: E = 393 (199) pmol x l(-1) (CEx) vs 174 (85) pmol x l(-1) (CS), NE = 4593 (2640) pmol x l(-1) (CEx) vs 1548 (505) pmol x l(-1) (CS), and hGH = 274 (340) pmol x l(-1) (CEx)vs 64 (112) pmol x l(-1) (CS). At 40 degrees C, bout 1: E = 596 (346) pmol x l(-1) (HEx) vs 323 (181) pmol x l(-1) (HS), NE = 7789 (5129) pmol x l(-1) (HEx) vs 1527 (605) pmol x l(-1) (HS), and hGH = 453 (494) pmol x l(-1) (HEx) vs 172 (355) pmol x l(-1) (HS). However, concentrations of plasma cortisol were increased only in response to exercise in the heat [HEx = 364 (168) nmol x l(-1) vs HS = 295 (114) nmol x l(-1)]. Compared to exercise at room temperature, plasma levels of E, NE and cortisol were all higher during exercise in the heat (P < 0.001 in all cases). The repetition of exercise did not significantly alter the pattern of change in cortisol or hGH levels in either environmental condition. However, repetition of exercise in the heat increased circulatory and psychological stress, with significantly (P < 0.001) higher plasma concentrations of E and NE. These results indicate a differential response of the various stress hormones to heat exposure and repeated moderate exercise.
为了确定热暴露是否会改变对适度、重复运动的激素反应，11名健康男性受试者[年龄=27.1（3.0）岁；最大耗氧量，VO2max = 47.6（6.2）ml·kg·min⁻¹；均值（标准差）]根据随机区组设计被分配到四种不同的实验条件。在热中性（23℃）或加热（40℃，相对湿度30%）气候舱中，受试者进行了两种实验：一是进行自行车测力计运动（两次30分钟的运动，强度约为VO2max的50%，中间间隔45分钟恢复时间，分别为CEx和HEx条件），二是静坐3小时（CS和HS条件）。采集血样分析各种运动应激激素[肾上腺素（E）、去甲肾上腺素（NE）、多巴胺、皮质醇和人生长激素（hGH）]。被动加热并未显著改变这些激素中的任何一种的浓度。在两种环境条件下，运动均导致血浆E、NE和hGH水平显著升高（P < 0.001）。在23℃时，运动回合1：E = 393（199）pmol·L⁻¹（CEx）对比174（85）pmol·L⁻¹（CS），NE = 4593（2640）pmol·L⁻¹（CEx）对比1548（505）pmol·L⁻¹（CS），hGH = 274（340）pmol·L⁻¹（CEx）对比64（112）pmol·L⁻¹（CS）。在40℃时，运动回合1：E = 596（346）pmol·L⁻¹（HEx）对比323（181）pmol·L⁻¹（HS），NE = 7789（5129）pmol·L⁻¹（HEx）对比1527（605）pmol·L⁻¹（HS），hGH = 453（494）pmol·L⁻¹（HEx）对比172（355）pmol·L⁻¹（HS）。然而，血浆皮质醇浓度仅在热环境中运动时升高[HEx = 364（168）nmol·L⁻¹对比HS = 295（114）nmol·L⁻¹]。与室温下运动相比，热环境中运动时血浆E、NE和皮质醇水平均更高（所有情况P < 0.001）。运动的重复在两种环境条件下均未显著改变皮质醇或hGH水平的变化模式。然而，在热环境中重复运动增加了循环和心理应激，血浆E和NE浓度显著更高（P < 0.001）。这些结果表明各种应激激素对热暴露和重复适度运动有不同的反应。
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