Ryu S, Choi S K, Joung S S, Suh H, Cha Y S, Lee S, Lim K
Institute of Elderly Health, Seoul, Korea.
J Nutr Sci Vitaminol (Tokyo). 2001 Apr;47(2):139-46. doi: 10.3177/jnsv.47.139.
Caffeine is one of the famous ergogenic aids in the athletic field. Caffeine has been known to stimulate lipolysis that spares stored glycogen utilization during moderate intensity exercise. Therefore, we investigated the effects of caffeine ingestion on exercise performance in rats and athletes. Rats were administered the caffeine (6 mg/kg) 1 h prior to the exercise then were run on a treadmill at a speed of 20 m/min. They were decapitated at 0 min, 30 min, 60 min of exercise, and exhausted time point. Human subjects ingested the caffeine (5 mg/kg) 1 h prior to the exercise. They exercised on a cycle ergometer at 60% of their VO2max for 45 min, and then the exercise intensity was increased to 80% of their VO2max until exhaustion. Blood and breathing gas samples were collected and calculated every 10 min during exercise. Respiratory exchange ratio of the caffeine trial was significantly lower than that of the placebo trial in the athletes' study (p<0.05). Blood free fatty acid (FFA) levels in studies of both rats and athletes were increased by caffeine ingestion during exercise (p<0.05). Blood lactate levels were also increased during exercise in both rats and athletes (p<0.05). Increased FFA and glycerol concentrations reduced glycogen utilization during exercise compared with placebo group in rats. In addition, endurance time to exhaustion was significantly increased by the caffeine ingestion in both rats and athletes (p<0.05). These results suggest that the caffeine ingestion enhanced endurance performance resulting from spare stored glycogen with increasing lipolysis from adipose tissues and fat oxidation during exercise both in rats and in athletes.
咖啡因是运动领域著名的促力剂之一。已知咖啡因能刺激脂肪分解，在中等强度运动期间节省糖原储备的利用。因此，我们研究了摄入咖啡因对大鼠和运动员运动表现的影响。大鼠在运动前1小时给予咖啡因（6毫克/千克），然后在跑步机上以20米/分钟的速度跑步。在运动0分钟、30分钟、60分钟以及力竭时间点将其断头处死。人类受试者在运动前1小时摄入咖啡因（5毫克/千克）。他们在功率自行车上以其最大摄氧量的60%运动45分钟，然后将运动强度增加到其最大摄氧量的80%直至力竭。在运动期间每10分钟采集并计算血液和呼吸气体样本。在运动员的研究中，咖啡因试验的呼吸交换率显著低于安慰剂试验（p<0.05）。在大鼠和运动员的研究中，运动期间摄入咖啡因均使血液游离脂肪酸（FFA）水平升高（p<0.05）。大鼠和运动员在运动期间血液乳酸水平也升高（p<0.05）。与安慰剂组相比，大鼠运动期间游离脂肪酸和甘油浓度升高减少了糖原利用。此外，大鼠和运动员摄入咖啡因均显著增加了力竭的耐力时间（p<0.05）。这些结果表明，摄入咖啡因增强了耐力表现，这是由于在大鼠和运动员中，运动期间脂肪组织脂肪分解增加及脂肪氧化，从而节省了糖原储备所致。
