A meta-analysis on the effects of caffeine ingestion on swimming performance

Purpose Caffeine is a popular ergogenic aid, but its effects on swimming performance are not yet fully clear. Therefore, the purpose of this paper is to examine the effects of caffeine on swimming performance. Design/methodology/approach Crossover placebo-controlled studies that explored the effects of caffeine on swimming performance were included. Six databases were searched to find relevant studies with additional forward and backward citation tracking. The data were pooled in a random-effects meta-analysis. Findings Eight studies were included in the review. The main meta-analysis showed a significant ergogenic effect of caffeine ingestion on swimming performance (Cohen’s d : –0.20; 95% confidence interval: −0.32, −0.08; p = 0.0008; –1.7%). In the analysis for short-distance swimming events, caffeine ingestion had a significant ergogenic effect on swimming performance (Cohen’s d : –0.14; 95% confidence interval: –0.27, −0.01; p = 0.03; −1.4%). An ergogenic effect of caffeine was also found in the analysis for moderate-to-long swimming distance events (Cohen’s d : –0.36; 95% confidence interval: −0.67, −0.05; p = 0.02; −2.2%). Originality/value The present meta-analysis found that caffeine ingestion decreases the time needed to complete a given swimming event. While these ergogenic effects may be classified as small, they are likely important in swimming, where narrow margins commonly determine placings.