Effects of caffeine on exercise performance in sedentary females

The purpose of the study was to examine the effect of caffeine ingestion on total work,average power,oxygen consumption (vo2),respiratory exchange ratio (rer),ratings of perceived exertion (rpe),heart rate (hr) and energy expenditure (kj) during stationary cycling at a standardised power output,as well as during a set time period where participants were required to cycle as fast as they could. ten healthy,sedentary,female,non- regular caffeine users completed 15 min of stationary cycling at a standardised power output equating to 65% hrmax (phase a),followed by 10 min of stationary cycling where they were required to cycled as fast as they could (phase b) after ingesting 6.0 mg·kg-1 of caffeine or placebo 60 min prior to exercise. vo2 and energy expenditure were significantly higher at the end of phase a (p = 0.008 and p = 0.011,respectively). all other variables examined in phase a were similar between trials. in phase b,there were no significant differences found for any variable assessed. while caffeine ingestion resulted in signifi- cant increases in vo2 and energy expenditure during steady- state exercise,it did not improve cycling performance during a 10 min trial where participants were required to cycle as fast as they could. © journal of sports science and medicine.