Marino F E, Mbambo Z, Kortekaas E, Wilson G, Lambert M I, Noakes T D, Dennis S C
Human Movement Studies Unit, Charles Sturt University, Bathurst, NSW, Australia.
Pflugers Arch. 2000 Dec;441(2-3):359-67. doi: 10.1007/s004240000432.
The purpose of this study was to examine the extent to which lighter runners might be more advantaged than larger, heavier runners during prolonged running in warm humid conditions. Sixteen highly trained runners with a range of body masses (55-90 kg) ran on a motorised treadmill on three separate occasions at 15, 25 or 35 degrees C, 60% relative humidity and 15 km x h(-1) wind speed. The protocol consisted of a 30-min run at 70% peak treadmill running speed (sub-max) followed by a self-paced 8-km performance run. At the end of the submax and 8-km run, rectal temperature was higher at 35 degrees C (39.5+/-0.4 degrees C, P<0.05) compared with 15 degrees C (38.6+/-0.4 degrees C) and 25 degrees C (39.1+/-0.4 degrees C) conditions. Time to complete the 8-km run at 35 degrees C was 30.4+/-2.9 min (P<0.05) compared with 27.0+/-1.5 min at 15 degrees C and 27.4+/-1.5 min at 25 degrees C. Heat storage determined from rectal and mean skin temperatures was positively correlated with body mass (r=0.74, P<0.0008) at 35 degrees C but only moderately correlated at 25 degrees C (r=0.50, P<0.04), whereas no correlation was evident at 15 degrees C. Potential evaporation estimated from sweat rates was positively associated with body mass (r=0.71, P<0.002) at 35 degrees C. In addition, the decreased rate of heat production and mean running speed during the 8-km performance run were significantly correlated with body mass (r=-0.61, P<0.02 and r=-0.77, P<0.0004, respectively). It is concluded that, compared to heavier runners, those with a lower body mass have a distinct thermal advantage when running in conditions in which heat-dissipation mechanisms are at their limit. Lighter runners produce and store less heat at the same running speed; hence they can run faster or further before reaching a limiting rectal temperature.
本研究的目的是探讨在温暖潮湿环境下进行长时间跑步时，体重较轻的跑步者相比体型较大、体重较重的跑步者可能具有多大优势。16名经过高度训练、体重范围在55至90千克之间的跑步者，在电动跑步机上于三种不同环境下各跑三次，温度分别为15、25或35摄氏度，相对湿度60%，风速15千米/小时。实验方案包括以跑步机峰值速度的70%进行30分钟的跑步（次最大强度），随后进行一次8千米的自定速度的耐力跑。在次最大强度跑步和8千米跑结束时，直肠温度在35摄氏度时（39.5±0.4摄氏度，P<0.05）高于15摄氏度时（38.6±0.4摄氏度）和25摄氏度时（39.1±0.4摄氏度）。在35摄氏度环境下完成8千米跑的时间为30.4±2.9分钟（P<0.05），而在15摄氏度时为27.0±1.5分钟，25摄氏度时为27.4±1.5分钟。由直肠温度和平均皮肤温度确定的蓄热量在35摄氏度时与体重呈正相关（r = 0.74，P<0.0008），但在25摄氏度时仅呈中度相关（r = 0.50，P<0.04），而在15摄氏度时无明显相关性。根据出汗率估算的潜在蒸发量在35摄氏度时与体重呈正相关（r = 0.71，P<0.002）。此外，在8千米耐力跑过程中，产热率的降低和平均跑步速度与体重显著相关（分别为r = -0.61，P<0.02和r = -0.77，P<0.0004）。研究得出结论，与体重较重的跑步者相比，体重较轻的跑步者在散热机制达到极限的环境中跑步时具有明显的热优势。体重较轻的跑步者在相同跑步速度下产生和储存的热量更少；因此，他们在达到极限直肠温度之前能够跑得更快或更远。
