Arogyasami J, Yang H T, Winder W W
Department of Zoology, Brigham Young University, Provo, UT 84602.
Med Sci Sports Exerc. 1989 Apr;21(2):173-7.
Caffeine has been reported to enhance performance by increasing lipid oxidation and sparing liver and muscle glycogen in human subjects during prolonged endurance exercise. In the present study, the effects of intravenous caffeine on the liver and muscle glycogenolysis during exercise in endurance trained rats were investigated. Male endurance trained rats (2 h.d-1 for 6-7 wk) were given injections of 5 mg.kg-1 caffeine (5 CAF), 25 mg.kg-1 caffeine (25 CAF), or 0.9% sodium chloride (SAL) and were run on the treadmill for 45 min, 90 min, or until exhaustion at 26 m.min-1 up a 15% grade. Intravenous caffeine did not enhance the endurance run time: 5 CAF = 149 +/- 14 min, 25 CAF = 152 +/- 10 min, and SAL = 176 +/- 10 min. Caffeine did not influence the rate of liver glycogenolysis during exercise [liver glycogen (mmol glucose units.g-1) after 90 min: 5 CAF = 139 +/- 26, 25 CAF = 133 +/- 25, and SAL = 120 +/- 32]. Liver cAMP, muscle glycogen, plasma free fatty acids, blood glucose, and lactate were likewise not affected by caffeine [plasma free fatty acids (mM) after 90 min: 5 CAF = 0.42 +/- 0.04, 25 CAF = 0.45 +/- 0.07, and SAL = 0.41 +/- 0.05]. These data indicate that intravenous caffeine does not enhance the endurance run time or alter the plasma free fatty acids or liver and muscle glycogen utilization in endurance trained rats.
据报道，在长时间耐力运动期间，咖啡因可通过增加人体受试者的脂质氧化以及节省肝脏和肌肉糖原，来提高运动表现。在本研究中，研究了静脉注射咖啡因对耐力训练大鼠运动期间肝脏和肌肉糖原分解的影响。对雄性耐力训练大鼠（6 - 7周，每天训练2小时）注射5毫克/千克咖啡因（5 CAF）、25毫克/千克咖啡因（25 CAF）或0.9%氯化钠（SAL），然后在跑步机上以26米/分钟的速度、15%的坡度跑步45分钟、90分钟或直至力竭。静脉注射咖啡因并未延长耐力跑时间：5 CAF组 = 149 ± 14分钟，25 CAF组 = 152 ± 10分钟，SAL组 = 176 ± 10分钟。咖啡因不影响运动期间肝脏糖原分解速率[9分钟后肝脏糖原（毫摩尔葡萄糖单位/克）：5 CAF组 = 139 ± 26，25 CAF组 = 133 ± 25，SAL组 = 120 ± 32]。肝脏环磷酸腺苷（cAMP）、肌肉糖原、血浆游离脂肪酸、血糖和乳酸同样不受咖啡因影响[90分钟后血浆游离脂肪酸（毫摩尔/升）：5 CAF组 = 0.42 ± 0.04，25 CAF组 = 0.45 ± 0.07，SAL组 = 0.41 ± 0.05]。这些数据表明，静脉注射咖啡因不会延长耐力训练大鼠的耐力跑时间，也不会改变血浆游离脂肪酸或肝脏和肌肉糖原的利用情况。
