Caffeine plus sodium bicarbonate against placebo raised mean power by 8.43 W (95% CI 1.85 to 15.00) and cut time-trial time by about 1.6% (ratio of means 0.984, 0.970 to 0.998) in a meta-analysis of 13 crossover trials, but both results lost significance when single studies were left out, and the pair gave no significant mean-power gain over caffeine or bicarbonate alone; gut tolerance and perceived exertion showed no consistent effect (narrative synthesis)

Chen, Tu and Wang asked whether taking caffeine and sodium bicarbonate together gives more than either alone, and what the pair does to blood buffering, lactate, perceived exertion and gut comfort.

They searched three databases up to 18 July 2026 and pooled 13 crossover trials with random-effects models, allowing for the within-person design of crossovers and testing robustness by leaving out one study at a time and by trying other correlation values.

Against placebo the combination raised mean power by about 8 W and shortened time-trial completion time by an estimated 1.6%, but each result stopped being significant when certain single studies were removed, which the authors read as limited robustness. Against caffeine alone or bicarbonate alone the combination did not significantly raise mean power.

Blood bicarbonate and post-exercise lactate rose against placebo, the bicarbonate result resting on heterogeneous or few studies. Narratively, the trials showed no consistent effect on perceived exertion or gut tolerance.

The authors conclude that the combination may give modest gains over placebo whose significance hangs on single studies, that an added benefit over either supplement alone is not established, and that its gut tolerability remains uncertain.