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Effect of different protocols of caffeine intake on metabolism and endurance performance

2002; American Physiological Society; Volume: 93; Issue: 3 Linguagem: Inglês

10.1152/japplphysiol.00249.2002

8750-7587

Gregory R. Cox, Ben Desbrow, Paul G. Montgomery, Megan E. Anderson, Clinton R. Bruce, Theodore A. Macrides, David T. Martin, Angela Moquin, Alan D. Roberts, John A. Hawley, Louise M. Burke,

Cardiovascular and exercise physiology

Competitive athletes completed two studies of 2-h steady-state (SS) cycling at 70% peak O 2 uptake followed by 7 kJ/kg time trial (TT) with carbohydrate (CHO) intake before (2 g/kg) and during (6% CHO drink) exercise. In Study A, 12 subjects received either 6 mg/kg caffeine 1 h preexercise (Precaf), 6 × 1 mg/kg caffeine every 20 min throughout SS (Durcaf), 2 × 5 ml/kg Coca-Cola between 100 and 120 min SS and during TT (Coke), or placebo. Improvements in TT were as follows: Precaf, 3.4% (0.2–6.5%, 95% confidence interval); Durcaf, 3.1% (−0.1–6.5%); and Coke, 3.1% (−0.2–6.2%). In Study B, eight subjects received 3 × 5 ml/kg of different cola drinks during the last 40 min of SS and TT: decaffeinated, 6% CHO (control); caffeinated, 6% CHO; decaffeinated, 11% CHO; and caffeinated, 11% CHO (Coke). Coke enhanced TT by 3.3% (0.8–5.9%), with all trials showing 2.2% TT enhancement (0.5–3.8%; P < 0.05) due to caffeine. Overall, 1) 6 mg/kg caffeine enhanced TT performance independent of timing of intake and 2) replacing sports drink with Coca-Cola during the latter stages of exercise was equally effective in enhancing endurance performance, primarily due to low intake of caffeine (∼1.5 mg/kg).