Fisher S M, McMurray R G, Berry M, Mar M H, Forsythe W A
Int J Sports Med. 1986 Oct;7(5):276-80. doi: 10.1055/s-2008-1025774.
The effect of caffeine on the exercise responses of six women habituated to caffeine (greater than 600 mg/day) was examined during 1-h running at 75% VO2 max on a motorized treadmill. Each subject completed a placebo (PL) and a caffeine ingestion (CC) trial while maintaining normal caffeine intake. The subject then abstained from caffeine for 4 days and again ran after receiving caffeine (CW). Caffeine dosage for all trials was 5 mg/kg body weight. Ingestion of caffeine after withdrawal (CW) resulted in the greatest physiologic effects. Exercise oxygen uptake was significantly elevated by 0.17 l/min over the PL and CC trials (P less than 0.05). The CW trials resulted in an overall R value of 0.79 +/- 0.04 compared with 0.85 +/- 0.08 for the PL and 0.83 +/- 0.04 for the CC trials. Caffeine had its greatest effect on the resting free fatty acid levels after withdrawal: 1104 +/- 425 mu Eq/l compared with 543 +/- 288 for the PL and 839 +/- 526 for the CC. Postexercise lactates were similar for all trials. Post-exercise plasma norepinephrine and dopamine were the highest after the CW trials. The results suggest that habitually high caffeine users acquire a tolerance to caffeine which reduces its effects during prolonged exercise. Furthermore, to magnify the effect of caffeine, habitual users should withdraw from caffeine use for about 4 days.
研究了咖啡因对6名习惯饮用咖啡因（每日超过600毫克）的女性运动反应的影响，她们在电动跑步机上以75%最大摄氧量进行1小时跑步。每位受试者在维持正常咖啡因摄入量的情况下完成了一次安慰剂（PL）试验和一次咖啡因摄入（CC）试验。然后受试者停用咖啡因4天，之后在摄入咖啡因后再次进行跑步（CW）。所有试验的咖啡因剂量均为5毫克/千克体重。戒断后摄入咖啡因（CW）产生的生理效应最大。与PL和CC试验相比，运动摄氧量显著提高了0.17升/分钟（P<0.05）。CW试验的总体R值为0.79±0.04，而PL试验为0.85±0.08，CC试验为0.83±0.04。咖啡因对戒断后的静息游离脂肪酸水平影响最大：为1104±425微当量/升，而PL试验为543±288，CC试验为839±526。所有试验的运动后乳酸水平相似。运动后血浆去甲肾上腺素和多巴胺在CW试验后最高。结果表明，习惯性高咖啡因使用者会对咖啡因产生耐受性，这会降低其在长时间运动中的作用。此外，为了增强咖啡因的作用，习惯性使用者应停用咖啡因约4天。
