Layden Joseph D, Patterson Mark J, Nimmo Myra A
Strathclyde Institute for Biomedical Sciences, University of Strathclyde, Glasgow, UK.
Med Sci Sports Exerc. 2002 May;34(5):774-9. doi: 10.1097/00005768-200205000-00008.
The influence of cold air exposure on fuel utilization during prolonged cycle exercise was investigated.
Nine male subjects cycled for 90 min in ambient temperatures of -10 degrees C, 0 degrees C, 10 degrees C, and 20 degrees C. External work performed between conditions was constant. Mean oxygen consumption (VO2) over the 90 min in the 20 degrees C trial corresponded to 64 +/- 5.8% VO2peak.
Although mean skin temperature was different between trials (P < 0.05), rectal temperatures were not different. At -10 degrees C and 0 degrees C, the respiratory exchange ratio was higher compared with 10 degrees C and 20 degrees C (0.98 +/- 0.01 and 0.97 +/- 0.01 vs 0.92 +/- 0.01 and 0.91 +/- 0.01; P < 0.05). The associated rates of fat oxidation were lower at -10 degrees C and 0 degrees C compared with 10 degrees C and 20 degrees C (0.15 +/- 0.06 and 0.17 +/- 0.06 vs 0.35 +/- 0.06 and 0.40 +/- 0.04 g.min-1; P < 0.05). Blood glycerol was lower at -10 degrees C and 0 degrees C compared with 20 degrees C (P < 0.05); mean values were 0.13 +/- 0.0, 0.13 +/- 0.0, and 0.18 +/- 0.0 mmol.L-1 for the -10 degrees C, 0 degrees C, and 20 degrees C trials, respectively. Mean VO2 was lower in the -10 degrees C trial than the 20 degrees C trial (2.53 +/- 0.06 vs 2.77 +/- 0.09. L.min-1; P < 0.05). Mean blood glucose concentrations were lower at -10 degrees C than 20 degrees C (4.9 +/- 0.2 vs 5.3 +/- 0.1 mmol.L-1; P < 0.05). Although plasma epinephrine concentrations were greater during the 20 degrees C trial compared with all other trials (P < 0.05), plasma norepinephrine did not differ between trials.
The diminished fat oxidation at colder temperatures potentially reflects a reduction in lipolysis and/or mobilization of FFA or impairment in the oxidative capacity of the muscle.
研究长时间循环运动期间暴露于冷空气对燃料利用的影响。
九名男性受试者在-10℃、0℃、10℃和20℃的环境温度下进行90分钟的骑行。不同条件下的外部做功保持恒定。20℃试验中90分钟的平均耗氧量（VO2）相当于VO2峰值的64±5.8%。
尽管各试验间平均皮肤温度不同（P<0.05），但直肠温度无差异。在-10℃和0℃时，呼吸交换率高于10℃和20℃时（0.98±0.01和0.97±0.01对比0.92±0.01和0.91±0.01；P<0.05）。与10℃和20℃相比，-10℃和0℃时的脂肪氧化相关速率较低（0.15±0.06和0.17±0.06对比0.35±0.06和0.40±0.04克·分钟-1；P<0.05）。-10℃和0℃时的血甘油水平低于20℃时（P<0.05）；-10℃、0℃和20℃试验的平均值分别为0.13±0.0、0.13±0.0和0.18±0.0毫摩尔·升-1。-10℃试验中的平均VO2低于20℃试验（2.53±0.06对比2.77±0.09升·分钟-1；P<0.05）。-10℃时的平均血糖浓度低于20℃时（4.9±0.2对比5.3±0.1毫摩尔·升-1；P<0.05）。尽管20℃试验期间的血浆肾上腺素浓度高于所有其他试验（P<0.05）,但各试验间血浆去甲肾上腺素无差异。
在较低温度下脂肪氧化减少可能反映了脂肪分解和/或游离脂肪酸动员的减少，或肌肉氧化能力的损害。
