Shibasaki M, Inoue Y, Kondo N, Iwata A
Graduate School of Science and Technology, Kobe University, Japan.
Eur J Appl Physiol Occup Physiol. 1997;75(3):212-8. doi: 10.1007/s004210050150.
Seven prepubertal boys (aged 10-11 years) and eleven young men (aged 21-25 years), matched for skinfold thickness and maximal oxygen uptake (VO2max) per unit of mass, cycled at an intensity of approximately 40% VO2max for 45 min in a warm condition (30 degrees C, 45% relative humidity). During exercise no age-related differences were observed for the increases in rectal temperature (Tre) and heart rate (HR), although the absolute Tre and HR were significantly greater for the boys because of a higher initial baseline (P < 0.05). Total body sweating rate [181 (SEM 12) vs 245 (SEM 12) g.m-2(.)45 min-1; P < 0.002] and local sweating rates (msw) on chest, back, and forearm were significantly lower for the boys (P < 0.001), as was metabolic heat production [203 (SEM 9) vs 276 (SEM 9) W.m-2; P < 0.01]. The lower msw in the boys was due to a lower output per activated sweat gland, even though they had a higher activated sweat gland density regardless of site. In contrast, cutaneous blood flow by laser Doppler flowmetry (LDF) in the boys was significantly greater on the chest and back, compared to the men (P < 0.003). The age-related differences in cutaneous vascular conductance (CVC) were more marked because of lower mean arterial pressure in the boys during exercise. However, forearm LDF and CVC were significantly lower for the boys (P < 0.008). No significant differences in LDF among sites were observed for the boys, whereas for the men LDF on the forearm was significantly greater than on the chest and back (P < 0.01). The boys showed lower mean skin temperatures (especially on the back and chest despite greater increments of LDF) after starting to sweat, whereas the men remained unchanged, suggesting that the heat loss on the trunk in the boys was promoted by greater increments of LDF despite lower msw, compared to the young men. It was concluded that during moderate exercise in an air temperature at 30 degrees C, prepubertal boys could thermoregulate as efficiently as young men by greater vasodilatation on their trunk despite lower msw. Furthermore regional differences may exist in the maturation-related modification of vasodilatation.
7名青春期前男孩（年龄10 - 11岁）和11名年轻男性（年龄21 - 25岁），根据皮褶厚度和每单位质量的最大摄氧量（VO2max）进行匹配，在温暖环境（30摄氏度，相对湿度45%）下以约40%VO2max的强度骑行45分钟。运动期间，直肠温度（Tre）和心率（HR）的升高未观察到与年龄相关的差异，尽管由于初始基线较高，男孩的绝对Tre和HR显著更高（P < 0.05）。男孩的全身出汗率[181（标准误12）对245（标准误12）g·m⁻²·45min⁻¹；P < 0.002]以及胸部、背部和前臂的局部出汗率（msw）显著更低（P < 0.001），代谢产热也是如此[203（标准误9）对276（标准误9）W·m⁻²；P < 0.01]。男孩较低的msw是由于每个激活汗腺的输出较低，尽管无论部位如何他们都有较高的激活汗腺密度。相比之下，通过激光多普勒血流仪（LDF）测量，男孩胸部和背部的皮肤血流量显著高于男性（P < 0.003）。由于男孩运动期间平均动脉压较低，皮肤血管传导率（CVC）与年龄相关的差异更为明显。然而，男孩前臂的LDF和CVC显著更低（P < 0.008）。男孩各部位之间的LDF未观察到显著差异，而男性前臂的LDF显著高于胸部和背部（P < 0.01）。出汗开始后，男孩的平均皮肤温度较低（尤其是背部和胸部，尽管LDF增加幅度更大），而男性则保持不变，这表明与年轻男性相比，尽管msw较低，但男孩躯干上更大的LDF增加促进了热量散失。得出的结论是，在30摄氏度气温下进行适度运动时，青春期前男孩尽管msw较低，但通过躯干上更大的血管舒张能够与年轻男性一样有效地进行体温调节。此外，血管舒张的成熟相关改变可能存在区域差异。
