Diurnal variation in the control of ventilation in response to rising body temperature during exercise in the heat.
Diurnal variation in the control of ventilation in response to rising body temperature during exercise in the heat.
复制标题
炎热运动期间，随着体温升高，通气控制的昼夜变化。
DOI：
10.1152/ajpregu.00484.2015
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Nishiyasu T.
中科院分区：
文献类型：
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作者：
Tsuji B;Honda Y;Kondo N;Nishiyasu T.
我们研究了运动时热致过度换气是否受到一天中的时间的影响，因为昼夜变化会导致傍晚的核心温度升高。19名男性受试者被分为两个实验（方案1，n= 10；方案2，n= 9）。在方案1中，受试者在早上（0600）和晚上（1800）在高温（37°C和50% RH）下以50%峰值摄氧量进行循环运动。结果显示，静息和运动时的基线食道温度（Tes）在晚上明显高于早上（0.5°C）。晨、晚两组患者的分钟通气量分别由10 min时的54.3±7.9、54.9±6.8 l/min上升至48.5 min时的71.4±8.1、76.5±11.8 l/min （p均< 0.01）。不同时间对血氧浓度无显著影响（P= 0.44）。当将输出的V值与tesas热输入的V值进行对比时，傍晚时V值升高的testhreshold值高于早晨（37.2±0.7°C vs. 36.6±0.6°C，P= 0.009），表明相同核心温度下傍晚的通气响应较小。在方案二中，通过将受试者浸泡在冷水中，将与昼夜节律相关的较高休息时间降低到与早晨相同的温度。重要的是，运动过程中V值变化的时间过程在晚上较小，但V值阈值在晚上仍然高于早晨（P< 0.001）。总的来说，这些结果表明，尽管晚上的核心温度较高，但白天的时间对在高温下运动时过度换气的时间过程没有影响。这可能是由于响应核心温度上升的通风控制的昼夜变化。
We investigated whether heat-induced hyperventilation during exercise is affected by time of day, as diurnal variation leads to higher core temperatures in the evening. Nineteen male subjects were divided into two experiments (protocol 1,n= 10 andprotocol 2,n= 9). Inprotocol 1, subjects performed cycle exercise at 50% peak oxygen uptake in the heat (37°C and 50% RH) in the morning (0600) and evening (1800). Results showed that baseline resting and exercising esophageal temperature (Tes) were significantly (0.5°C) higher in the evening than morning. Minute ventilation (V̇e) increased from 54.3 ± 7.9 and 54.9 ± 6.8 l/min at 10 min to 71.4 ± 8.1 and 76.5 ± 11.8 l/min at 48.5 min in the morning and evening, respectively (bothP< 0.01). Time of day had no effect on V̇e(P= 0.44). When V̇eas the output response was plotted againstTesas thermal input, theTesthreshold for increases in V̇ewas higher in the evening than morning (37.2 ± 0.7 vs. 36.6 ± 0.6°C,P= 0.009), indicating the ventilatory response to the same core temperature is smaller in the evening. Inprotocol 2, the circadian rhythm-related higher restingTesseen in the evening was adjusted down to the same temperature seen in the morning by immersing the subject in cold water. Importantly, the time course of changes in V̇eduring exercise were smaller in the evening, but the threshold for V̇eremained higher in the evening than morning (P< 0.001). Collectively, those results suggest that time of day has no effect on time course hyperventilation during exercise in the heat, despite the higher core temperatures in the evening. This is likely due to diurnal variation in the control of ventilation in response to rising core temperature.