EFFECTS OF CAFFEINE INGESTION ON METABOLISM AND EXERCISE PERFORMANCE

  • 1 January 1978
    • journal article
    • research article
    • Vol. 10  (3) , 155-158
Abstract
Competitive cyclists (2 females and 7 males) exercised until exhaustion on a bicycle ergometer at 80% of .ovrhdot.VO2 max [maximum rate of O2 ventilation]. One trial was performed 1 h after ingesting decaffeinated coffee (Trial D), while a 2nd trial (C) required that each subject consume coffee containing 330 mg of caffeine 60 min before the exercise. Following the ingestion of caffeine (Trial C), the subjects performed an average of 90.2 (SE .+-. 7.2) min of cycling as compared to an average of 75.5 (SE .+-. 5.1) min in the D Trial. Measurements of plasma free fatty acids, glycerol and respiratory exchange ratios evidenced a greater rate of lipid metabolism during the caffeine trial as compared to the decaffeinated exercise treatment. Calculations of carbohydrate (CHO) metabolism from respiratory exchange data revealed that the subjects oxidized roughly 240 g of CHO in both trials. Fat oxidation was significantly higher (P < 0.05) during the C Trial (118 g or 1.31 g/min) than in the D Trial (57 g or 0.75 g/min). On the average the participants rated (Perceived Exertion Scale) their effort during the C Trial to be significantly (P < 0.05) easier than the demands of the D treatment. The enhanced endurance performance observed in the C Trial was likely the combined effects of caffeine on lipolysis and its positive influence on nerve impulse transmission.

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