Investigation of modulation of skin vasodilator function by exercise training in a hot environment

热环境中的运动训练调节人体皮肤血液流动和出汗的控制系统，这是重要的体温调节功能。大多数关于运动训练(或热习服)对皮肤血管运动控制的调节的研究结果来自于对无毛(多毛)皮肤，通常是前臂皮肤的研究，但关于热习服对无毛(无毛)皮肤(如手掌)的影响的信息有限。在这个项目中，我们检测了在为期6天的运动-热习服计划之前和之后，全身加热期间无毛和非无毛皮肤的血管舒缩反应。我们还利用排汗频率(一种中枢舒缩活动的指标)检测了热习服对出汗控制的变化。8名健康的年轻志愿者接受了为期6天的热习服计划[在高温下以50%的耗氧峰值速率(36℃)进行总共80min的运动]。在热习服前后的几天里，我们检查了胸部和前臂的局部出汗率，排汗频率，以及全身加热时的食道温度。结果，短期热习服没有改变无毛皮肤对核心温度升高的血管反应，但降低了非无毛皮肤血管扩张的温度阈值。也有人提出，短期热习服调节中枢运动机制，降低出汗的温度阈值，但不改变出汗的外周机制。

Exercise training in a hot environment modulates the controlling system of skin blood flow and sweating, important thermoregulatory functions, in humans. Most of the findings regarding the modulation of skin vasomotor control by exercise training (or heat acclimation) are obtained from studies of nonglabrous (hairy) skin, usually forearm skin, but information about the influence of heat acclimation on glabrous (nonhairy) skin such as the palm is restricted. In this project, we examined the vasomotor responses in the glabrous and nonglabrous skin during whole body heating before and after a 6-day exercise-heat acclimation program. We also examined changes in the control of sweating by heat acclimation by using frequency of sweat expulsion, an index of central sudomotor activity. Eight healthy young volunteers underwent a six-day heat acclimation program [a total of 80-min exercise at 50% peak rate of oxygen consumption in the heat (36℃)]. In the days before and after the heat acclimation program, we examined the local sweating rate at the chest and forearm, frequency of sweat expulsion, and esophageal temperature during whole body heating using a water-perfused suit. As a result, short-term heat acclimation did not change the vascular response in glabrous skin to a raised core temperature but decreased the temperature threshold for vasodilation in nonglabrous skin. It was also suggested that short-term heat acclimation modulates central sudomotor mechanisms, decreasing the temperature threshold for sweating but does not change in the peripheral mechanism for sweating.