Effect of an Absolute Dose of Encapsulated Caffeine on Cycling Time Trial Performance in Average College-age Women

Few studies have examined ingestion of an absolute dose of caffeine in capsule form on the exercise performance of women with an average fitness level. PURPOSE: To investigate the effect of an absolute dose of encapsulated caffeine on cycling time-trial performance in women of average fitness level. METHODS: Four women (mean ± SD; age: 23±3 y, height: 164.2±6.0 cm, weight: 63.2±3.2 kg, body fat: 22.0±2.2%, VO2max: 35.1±5.9 mL/kg/min) participated in a pretest to assess VO2max followed by two experimental trials assigned in a double-blind, crossover design. During experimental trials, participants ingested either 600 mg of encapsulated caffeine or a placebo, followed by 60 min of seated rest. Then, 45 minutes of steady-state cycling at 50% VO2max was performed, immediately followed by a 15-min time trial to complete as much work as possible. RESULTS: There was no significant difference between trials in total work completed (caffeine: 123.7±20.4 kJ, placebo: 121.5±19.3 kJ; p=0.45), mean power output (caffeine: 137.5±22.6 kJ, placebo: 134.7±22.3 kJ; p=0.19), and peak power output (caffeine: 210.8±15.2 kJ, placebo: 213.8±34.0 kJ; p=0.82). There was no significant difference between trials in rating of perceived exertion at the end of the 15-min time trial (caffeine: 17.8±2.6, placebo: 18.8±1.3; p=0.25). CONCLUSIONS: Preliminary results of the current study did not show an ergogenic effect of an absolute dose of encapsulated caffeine on a 15-min cycling time trial performance in women of average aerobic fitness