Effects of caffeine ingestion on rating of perceived exertion during and after exercise: A meta-analysis

Abstract

The purpose of this study was to use the meta-analytic approach to examine the effects of caffeine ingestion on ratings of perceived exertion (RPE). Twenty-one studies with 109 effect sizes (ESs) met the inclusion criteria. Coding incorporated RPE scores obtained both during constant load exercise (n = 89) and upon termination of exhausting exercise (n = 20). In addition, when reported, the exercise performance ES was also computed (n = 16). In comparison to placebo, caffeine reduced RPE during exercise by 5.6% (95% CI (confidence interval), - 4.5% to - 6.7%), with an equivalent RPE ES of - 0.47 (95% CI, - 0.35 to - 0.59). These values were significantly greater (P < 0.05) than RPE obtained at the end of exercise (RPE % change, 0.01%; 95% CI, - 1.9 to 2.0%; RPE ES, 0.00,95% CI, - 0.17 to 0.17). In addition, caffeine improved exercise performance by 11.2% (95% CI; 4.6-17.8%). Regression analysis revealed that RPE obtained during exercise could account for ∼ 29% of the variance in the improvement in exercise performance. The results demonstrate that caffeine reduces RPE during exercise and this may partly explain the subsequent ergogenic effects of caffeine on performance. Copyright © Blackwell Munksgaard 2005.