Titlow L W, Ishee J H, Riggs C E
Human Performance Laboratory, University of Central Arkansas, Conway 72032.
J Sports Sci. 1991 Spring;9(1):15-22. doi: 10.1080/02640419108729851.
Caffeine consumption prior to athletic performance has become commonplace. The usual dosage is approximately 200 mg, a level of caffeine ingestion equivalent to two cups of brewed coffee. This study was designed to examine the effects of a common level of caffeine ingestion, specifically 200 mg, on metabolism during submaximal exercise performance in five males. The subjects performed two 60-min monitored treadmill workouts at 60% maximal heart rate during a 2-week period. The subjects were randomly assigned, double-blind to receive a caffeine or placebo capsule 60 min prior to exercise. Testing was performed in the afternoon following a midnight fast. Venous blood was withdrawn pre-exercise, every 15 min during the workout, and 10 min after recovery. Blood was analysed for free fatty acid, triglycerides, glucose, lactic acid, haemoglobin and haematocrit. The respiratory exchange ratio (R), perceived exertion (RPE) and oxygen uptake were measured every 4 min during exercise. An examination of the data with repeated-measures ANOVA revealed no significant differences between the two groups. Within the limitations of the study, it was concluded that 200 mg caffeine failed to affect metabolism during 60 min submaximal exercise.
在运动表现之前摄入咖啡因已变得很常见。通常剂量约为200毫克，这一咖啡因摄入量相当于两杯煮好的咖啡。本研究旨在考察常见咖啡因摄入量水平，即200毫克，对五名男性在次最大运动表现期间新陈代谢的影响。在两周内，受试者以最大心率的60%进行了两次60分钟的监测跑步机锻炼。受试者被随机分配，在运动前60分钟接受咖啡因或安慰剂胶囊，采用双盲方式。测试在午夜禁食后的下午进行。在运动前、锻炼期间每15分钟以及恢复后10分钟采集静脉血。对血液进行游离脂肪酸、甘油三酯、葡萄糖、乳酸、血红蛋白和血细胞比容分析。在运动期间每4分钟测量一次呼吸交换率（R）、主观用力程度（RPE）和摄氧量。用重复测量方差分析对数据进行检验，结果显示两组之间无显著差异。在该研究的局限性范围内，得出的结论是200毫克咖啡因在60分钟次最大运动期间未能影响新陈代谢。
