预热和预冷后，温暖的皮肤会改变心血管对骑行的反应。
Warm skin alters cardiovascular responses to cycling after preheating and precooling.
机构信息
Human Performance Laboratory, Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX.
出版信息
Med Sci Sports Exerc. 2015 Jun;47(6):1168-76. doi: 10.1249/MSS.0000000000000539.
PURPOSE
Exercise in hot conditions increases core (TC) and skin temperature (TSK) and can lead to a progressive rise in HR and decline in stroke volume (SV) during prolonged exercise. Thermoregulatory-driven elevations in skin blood flow (SkBF) adds complexity to cardiovascular regulation during exercise in these conditions. Presently, the dominant, although debated, view is that raising TSK increases SkBF and reduces SV through diminished venous return; however, this scenario has not been rigorously investigated across core and skin temperatures. We tested the hypothesis that high TSK would raise HR and reduce SV during exercise after precooling (cold water bath) and preheating (hot water bath) and that no relationship would exist between SkBF and SV during exercise.
METHODS
Non-endurance-trained individuals cycled for 20 min at 69% ± 1% VO₂peak on four occasions: cool skin-cool core (SkCCC), warm skin-cool core (SkWCC), cool skin-warm core (SkCCW), and warm skin-warm core (SkWCW) on separate days.
RESULTS
After precooling of TC, the rise in HR was greater in SkWCC than in SkCCC (P < 0.001), yet SV was similar (P = 0.26), which resulted in higher QC at min 20 in SkWCC (P < 0.01). Throughout exercise after preheating of TC, HR was higher (P < 0.001), SV was reduced (P < 0.01), and QC was similar (P = 0.40) in SkWCW versus SkCCW. When all trials were compared, there was no relationship between SkBF and SV (r = -0.08, P = 0.70); however, there was an inverse relationship between HR and SV (r = -0.75, P < 0.001).
CONCLUSIONS
These data suggest that when TSK is elevated during exercise, HR and TC will rise but SV will only be reduced when TC is also elevated above 38°C. Furthermore, changes in SV are not related to changes in SkBF.
目的
在炎热环境下运动可增加核心温度（TC）和皮肤温度（TSK），并导致在长时间运动中 HR 逐渐升高和 SV 逐渐降低。在这些条件下运动时，热调节引起的皮肤血流量（SkBF）增加会使心血管调节变得更加复杂。目前，尽管存在争议，但主导观点是，升高 TSK 通过减少静脉回流来增加 SkBF 并降低 SV；然而，这种情况尚未在整个核心和皮肤温度范围内进行严格的研究。我们假设，在预冷却（冷水浴）和预加热（热水浴）后，高 TSK 在运动期间会升高 HR 并降低 SV，并且在运动期间 SkBF 与 SV 之间不存在关系。
方法
非耐力训练个体在 4 天内分别进行 4 次试验：冷皮肤-冷核心（SkCCC）、暖皮肤-冷核心（SkWCC）、冷皮肤-暖核心（SkCCW）和暖皮肤-暖核心（SkWCW），每次试验均在 69%±1%VO₂peak 下进行 20 分钟。
结果
在 TC 预冷却后，SkWCC 中的 HR 升高大于 SkCCC（P<0.001），但 SV 相似（P=0.26），导致 SkWCC 中 min 20 的 QC 更高（P<0.01）。在 TC 预加热后整个运动过程中，SkWCW 中的 HR 更高（P<0.001），SV 降低（P<0.01），QC 相似（P=0.40）。当比较所有试验时，SkBF 与 SV 之间没有关系（r=-0.08，P=0.70）；然而，HR 与 SV 呈负相关（r=-0.75，P<0.001）。
结论
这些数据表明，当运动时 TSK 升高时，HR 和 TC 会升高，但只有当 TC 升高至 38°C 以上时，SV 才会降低。此外，SV 的变化与 SkBF 的变化无关。
Zotero 插件