Marino Frank E, Lambert Mike I, Noakes Timothy D
School of Human Movement Studies, Charles Sturt Univ., Bathurst NSW 2795, Australia.
J Appl Physiol (1985). 2004 Jan;96(1):124-30. doi: 10.1152/japplphysiol.00582.2003. Epub 2003 Aug 29.
The purpose of this study was to examine the running performances and associated thermoregulatory responses of African and Caucasian runners in cool and warm conditions. On two separate occasions, 12 (n = 6 African, n = 6 Caucasian) well-trained men ran on a motorized treadmill at 70% of peak treadmill running velocity for 30 min followed by an 8-km self-paced performance run (PR) in cool (15 degrees C) or warm (35 degrees C) humid (60% relative humidity) conditions. Time to complete the PR in the cool condition was not different between groups ( approximately 27 min) but was significantly longer in warm conditions for Caucasian (33.0 +/- 1.6 min) vs. African (29.7 +/- 2.3 min, P < 0.01) runners. Rectal temperatures were not different between groups but were higher during warm compared with cool conditions. During the 8-km PR, sweat rates for Africans (25.3 +/- 2.3 ml/min) were lower compared with Caucasians (32.2 +/- 4.1 ml/min; P < 0.01). Relative rates of heat production were less for Africans than Caucasians in the heat. The finding that African runners ran faster only in the heat despite similar thermoregulatory responses as Caucasian runners suggests that the larger Caucasians reduce their running speed to ensure an optimal rate of heat storage without developing dangerous hyperthermia. According to this model, the superior running performance in the heat of these African runners can be partly attributed to their smaller size and hence their capacity to run faster in the heat while storing heat at the same rate as heavier Caucasian runners.
本研究的目的是考察非洲裔和高加索裔跑步者在凉爽和温暖环境下的跑步表现及相关的体温调节反应。在两个不同的时间段，12名（n = 6名非洲裔，n = 6名高加索裔）训练有素的男性在电动跑步机上以跑步机峰值跑步速度的70%跑30分钟，随后在凉爽（15摄氏度）或温暖（35摄氏度）、潮湿（相对湿度60%）的环境下进行8公里的自定节奏跑步表现测试（PR）。在凉爽环境下完成PR的时间在两组之间没有差异（约27分钟），但在温暖环境下，高加索裔跑步者（33.0 +/- 1.6分钟）比非洲裔跑步者（29.7 +/- 2.3分钟，P < 0.01）明显更长。两组之间的直肠温度没有差异，但温暖环境下的直肠温度高于凉爽环境。在8公里的PR过程中，非洲裔跑步者的出汗率（25.3 +/- 2.3毫升/分钟）低于高加索裔跑步者（32.2 +/- 4.1毫升/分钟；P < 0.01）。在炎热环境中，非洲裔跑步者的相对产热率低于高加索裔跑步者。尽管非洲裔跑步者与高加索裔跑步者的体温调节反应相似，但只有在炎热环境中非洲裔跑步者跑得更快，这一发现表明，体型较大的高加索裔跑步者会降低跑步速度，以确保有最佳的热量储存率，而不会出现危险的体温过高。根据这一模型，这些非洲裔跑步者在炎热环境中卓越的跑步表现部分可归因于他们较小的体型，因此他们能够在炎热环境中以与体型较重的高加索裔跑步者相同的热量储存率跑得更快。
