Table 1.

Characteristics and findings of studies directly examining the effects of habitual caffeine intake on exercise performance

Study	Subjects	Habitual dose	Pre-trial dose	Performance trial	Performance outcome
Dodd et al. [20]	17 moderately trained males	< 25 mg/day for non-habitual users; > 300 mg/day for habitual users	3 and 5 mg/kg	Graded incremental cycle ergometer: increases of 30 W every 2 min until subjects could not maintain a set power output	No difference between habitual and non-habitual users in time to exhaustion
Bell and McLellan [22]	21 male and female subjects	< 50 mg/day for non-habitual users; ≥ 300 mg/day for habitual users	5 mg/kg	Time to exhaustion cycle ergometer at 80% VO2max	Habitual caffeine use appeared to reduce the ergogenic effects of caffeine
Beaumont et al. [69]	18 habitually low caffeine users	3 mg/kg	3 mg/kg	60-min cycle at 60% VO2peak, followed by maximum work completed in 30 min	Habitual caffeine use reduced the ergogenic effects of caffeine
Gonçalves et al. [23]	40 male endurance-trained cyclists	58 mg/day (low group); 143 mg/day (moderate group); 351 mg/day (high group)	6 mg/kg	Cycle ergometer time trial; set amount of work in shortest possible time	No effect of habitual caffeine intake

VO_2max maximal oxygen consumption, VO_2peak peak oxygen consumption