研究课题：自行车运动中咖啡因降低腿部肌肉疼痛的剂量依赖效应与心脏收缩压无关
供稿：运动科学系，乔治亚大学，雅典

    主要内容：本研究为组内双盲实验，目的是研究摄入2个剂量的咖啡因对于中等强度的自行车运动过程中腿部肌肉疼痛和血压的影响。平常摄入低剂量咖啡因的男性大学生服用2个剂量之一的咖啡因（每公斤体重5mg 或 10mg），或服用安慰剂。1小时后进行30分钟的中等强度自行车运动（60%）。药物使用顺序经过随机平衡，静止血压和心率在服用咖啡因前1小时或服用后1小时测定记录。在运动过程中，记录对于下列指标的影响：腿部肌肉疼痛、运动速率、血压、心率、耗氧量。咖啡因对心脏收缩压的影响呈剂量依赖性，但这种效果在运动中没有持续。咖啡因对腿部肌肉疼痛的舒缓效果分级，呈明显的剂量线性依赖性。服用10mg/kg体重，5 mg/kg体重咖啡因及安慰剂组平均疼痛分级分别为2.1+/-1.4, 2.6+/-1.5, t和3.5+/-1.7。

    结论：咖啡因对减轻运动中腿部肌肉疼痛呈现剂量依赖性，而此作用与咖啡因引起的心脏收缩压的增加无关。

Dose-dependent effect of caffeine on reducing leg muscle pain during cycling exercise is unrelated to systolic blood pressure.
O'Connor PJ, Motl RW, Broglio SP, Ely MR. Pain. 2004 Jun;109(3):291-8.
Department of Exercise Science, University of Georgia, Athens, GA.
This double-blind, within-subjects experiment examined the effects of ingesting two doses of caffeine on perceptions of leg muscle pain and blood pressure during moderate intensity cycling exercise. Low caffeine consuming college-aged males ingested one of two doses of caffeine (5 or 10mg.kg(-1) body background="../images_new/bg_hei.jpg" weight) or placebo and 1h later completed 30 min of moderate intensity cycling exercise (60%). The order of drug administration was counter-balanced. Resting blood pressure and heart rate were recorded immediately before and 1h after drug administration. Perceptions of leg muscle pain as well as work rate, blood pressure, heart rate, and oxygen uptake were recorded during exercise. Caffeine increased resting systolic pressure in a dose-dependent fashion but these blood pressure effects were not maintained during exercise. Caffeine had a significant linear effect on leg muscle pain ratings. The mean (+/-SD) pain intensity scores during exercise after ingesting 10mg.kg(-1) body background="../images_new/bg_hei.jpg" weight caffeine, 5mg.kg(-1) body background="../images_new/bg_hei.jpg" weight caffeine, and placebo were 2.1+/-1.4, 2.6+/-1.5, and 3.5+/-1.7, respectively. The results support the conclusion that caffeine ingestion has a dose-response effect on reducing leg muscle pain during exercise and that these effects do not depend on caffeine-induced increases in systolic blood pressure during exercise.

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