摘要：International Journal of Exercise Science 12(6): 412-424, 2019. This study examined effects of caffeine (CAF) on power output (PO) selection and associated physiological responses during cycling at moderate and high intensities prescribed by RPE (0-10 scale). Participants (n = 9) (VO2peak: 55.4 ± 6.32 mL · kg-1 · min-1) cycled for 20 min at RPE4 and 20 min at RPE7 separated by 10 min recovery following caffeine (CAF) (6 mg · kg-1) and placebo (PLA) ingestion. PO, HR, serum lactate [La], VO2, VE, and RER were recorded every 5 min. Session RPE (S-RPE) was recorded following 10 min recovery. Repeated-measures ANOVA’s, 2 (trial) x 4 (time pt), showed significantly greater PO during RPE4 for CAF (130 ± 23 W) vs PLA (112 ± 26 W) and during RPE7 (CAF: 165 ± 37 vs PLA: 143 ± 41 W). Overall HR, VO2, and VE were significantly greater for CAF vs PLA during RPE7. RER for RPE4 and RPE7 were not significantly different (CAF vs PLA). Overall [La] was significantly greater for CAF during RPE4 (CAF: 2.32 ± 0.94 vs PLA: 1.73 ± 1.09) and RPE7 (CAF: 3.22 ± 1.44 vs PLA: 2.22 ± 1.49). Paired T-tests for S-RPE revealed no significant difference for RPE4 (CAF: 4.0 ± 0.5 vs PLA: 3.7 ± 0.5) or RPE7 (CAF: 7.1 ± 0.3 vs PLA: 6.9 ± 0.6) despite greater PO for CAF. Although individual responses varied, the current study indicates caffeine ingestion results in elevated self-selected PO with significant systematic changes in associated physiological responses particularly at a higher intensity (RPE7).
