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% HR_max (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 significant 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.

• A 6.0 mg·kg dose of caffeine did not improve work done (J·kg) or mean power (W) during 10 min of self-paced stationery cycling in sedentary female participants.

• A 6.0 mg·kg dose of caffeine significantly increased VO and energy expenditure (kJ) during 15 min of steady-state stationery cycling in sedentary female participants.

• A 6.0 mg·kg dose of caffeine did not significantly affect RPE, RER or HR during 15 min of steady-state cycling or 10 min of cycling performed as fast as the participant could achieve, when compared to placebo, in sedentary female participants.