Falk B, Bar-Or O, MacDougall J D
Children's Exercise and Nutrition Centre, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada.
Med Sci Sports Exerc. 1992 Jun;24(6):688-94.
During exercise in a hot climate, children have been reported to have a less effective temperature regulation capability, compared with adults. It is likely that the transition from a child-like to an adult-like response occurs during puberty. To assess the association between the thermoregulatory response and physical maturation, three groups of circum-pubertal boys cycled at 50% VO2max (three 20-min bouts with 10-min rests), in a climatic chamber (42 degrees C, 20% relative humidity). Based on Tanner staging (pubic hair), 10 were classified as prepubertal (PP), 13 as midpubertal (MP), and eight as late pubertal (LP). Measurements included rectal and skin temperatures (Tre, Tsk), heart rate (HR), sweating rate (SR), oxygen consumption (VO2), and forearm blood flow (FBF). Tre, Tsk, and HR increased with time, with no significant difference among groups. Relative VO2 (ml O2.kg-1) was similar among groups. FBF was consistently higher in PP compared with LP. In spite of the higher SR (PP = 4.9 +/- 0.2, MP = 5.7 +/- 0.3, LP = 6.6 +/- 0.4 ml.min-1.m-2) (mean +/- SEM) among LP compared with PP, the rate of heat storage (PP = 5.5 +/- 0.4, MP = 5.3 +/- 0.4, LP = 6.8 +/- 0.3, kJ.h-1.kg-1) was also significantly higher among those in the LP group. Three of eight LP did not complete the session due to high Tre, while two of the 10 PP were unable to complete the session even though the physiologic heat strain was not high. The results suggest that the transition from a child-like to an adult-like thermoregulatory effectiveness in a hot, dry climate may occur at a somewhat later stage, but not during puberty.
据报道，在炎热气候下进行运动时，儿童的体温调节能力不如成年人有效。从儿童样反应向成人样反应的转变可能发生在青春期。为了评估体温调节反应与身体成熟之间的关联，三组青春期前后的男孩在气候室（42摄氏度，相对湿度20%）中以50%的最大摄氧量进行骑行（三组，每组20分钟，中间休息10分钟）。根据坦纳分期（阴毛），10名被归类为青春期前（PP），13名被归类为青春期中期（MP），8名被归类为青春期后期（LP）。测量指标包括直肠温度和皮肤温度（Tre、Tsk）、心率（HR）、出汗率（SR）、耗氧量（VO2）和前臂血流量（FBF）。Tre、Tsk和HR随时间增加，各组之间无显著差异。各组的相对VO2（ml O2·kg-1）相似。与LP组相比，PP组的FBF一直较高。尽管LP组的SR高于PP组（PP = 4.9 +/- 0.2，MP = 5.7 +/- 0.3，LP = 6.6 +/- 0.4 ml·min-1·m-2）（平均值 +/- 标准误），但LP组的蓄热率（PP = 5.5 +/- 0.4，MP = 5.3 +/- 0.4，LP = 6.8 +/- 0.3，kJ·h-1·kg-1）也显著更高。8名LP组中有3名因Tre过高而未完成实验，而10名PP组中有2名即使生理热应激不高也无法完成实验。结果表明，在炎热干燥的气候下，从儿童样到成人样的体温调节有效性转变可能发生在稍晚阶段，但不是在青春期。
