Effect of caffeine ingestion on time trial performance in cyclists: a systematic review and meta-analysis.

BACKGROUND

Caffeine, widely recognized as an ergogenic aid, has undergone extensive research, demonstrating its effectiveness to enhance endurance performance. However, there remains a significant gap in systematically evaluating its effects on time trial (TT) performance in cyclists.

PURPOSE

This meta-analysis aimed to determine the efficacy of caffeine ingestion to increase cycling TT performance in cyclists and to evaluate the optimal dosage range for maximum effect.

METHODS

A search of four databases was completed on 1 December 2023. The selected studies comprised crossover, placebo-controlled investigations into the effects of caffeine ingestion on cycling TT performance. Completion time (Time) and mean power output (MPO) were used as performance measures for TT. Meta-analyses were performed using a random-effects model to assess the standardized mean differences (SMD) in individual studies.

RESULTS

Fifteen studies met the inclusion criteria for the meta-analyses. Subgroup analysis showed that moderate doses of caffeine intake (4-6 mg/kg) significantly improved cycling performance (SMD  = -0.55, 95% confidence interval (CI) = -0.84 ~ -0.26,  < 0.01,  = 35%; SMD  = 0.44, 95% CI = 0.09 ~ 0.79,  < 0.05,  = 39%), while the effects of low doses (1-3 mg/kg) of caffeine were not significant (SMD  = -0.34, 95% CI = -0.84 ~ 0.17,  = 0.19,  = 0%; SMD  = 0.31, 95% CI = -0.02 ~ 0.65,  = 0.07,  = 0%).

CONCLUSION

A moderate dosage (4-6 mg/kg) of caffeine, identified as the optimal dose range, can significantly improve the time trial performance of cyclists, while a low dose (1-3 mg/kg) does not yield improvement. In addition, the improvements in completion time and mean power output resulting from a moderate dose of caffeine are essentially the same in cycling time trails.