Kenney W L
Laboratory for Human Performance Research, Pennsylvania State University, University Park 16802.
Eur J Appl Physiol Occup Physiol. 1988;57(1):120-5. doi: 10.1007/BF00691250.
Well matched unacclimatised older (age 55-68, 4 women, 2 men) and younger (age 19-30, 4 women, 2 men) subjects performed 75 min cycle exercise (approximately 40% VO2max) in a hot environment (37 degrees C, 60% rh). Rectal temperature (Tre), mean skin temperature (Tsk), arm blood flow (ABF, strain gauge plethysmography), and cardiac output (Q, CO2 rebreathing) were measured to examine age-related differences in heat-induced vasodilatation. Tre and Tsk rose to the same extent in each group during the exposure. There was no significant intergroup difference in sweat rate (older: 332 +/- 43 ml.m-2.h-1, younger: 435 +/- 49 ml.m-2.h-1; mean +/- SEM). However, the older subjects responded to exercise in the heat with a lower ABF response which could be attributed to a lower Q for the same exercise intensity. The slope of the ABF-Tre relationship was attenuated in the older subjects (9.3 +/- 1.3 vs 17.9 +/- 3.3 ml.100 ml-1.min-1.degrees C-1, p less than 0.05), but the Tre threshold for vasodilatation was about 37.0 degrees C for both groups. These results suggest an altered control of skin vasodilatation during exercise in the heat in older individuals. This attenuated ABF response appears to be unrelated to VO2max, and may reflect an age-related change in thermoregulatory cardiovascular function.
健康状况良好、未经适应训练的老年（年龄55 - 68岁，4名女性，2名男性）和年轻（年龄19 - 30岁，4名女性，2名男性）受试者在炎热环境（37摄氏度，相对湿度60%）中进行了75分钟的自行车运动（约为最大摄氧量的40%）。测量了直肠温度（Tre）、平均皮肤温度（Tsk）、手臂血流量（ABF，应变片体积描记法）和心输出量（Q，二氧化碳重呼吸法），以研究热诱导血管舒张的年龄差异。在暴露期间，每组的Tre和Tsk上升幅度相同。两组间的出汗率无显著差异（老年组：332±43 ml·m-2·h-1，年轻组：435±49 ml·m-2·h-1；平均值±标准误）。然而，老年受试者在热环境中运动时的ABF反应较低，这可能归因于相同运动强度下较低的心输出量。老年受试者中ABF - Tre关系的斜率减弱（9.3±1.3 vs 17.9±3.3 ml·100 ml-1·min-1·℃-1，p < 0.05），但两组血管舒张的Tre阈值均约为37.0℃。这些结果表明，老年人在热环境中运动时皮肤血管舒张的控制发生了改变。这种减弱的ABF反应似乎与最大摄氧量无关，可能反映了体温调节心血管功能的年龄相关变化。
