Pruscino, C. L., Ross, M. L., Gregory, A., Savage, B., & Troy, Flanagan. (2008). Effects of sodium bicarbonate, caffeine, and their combination on repeated 200-m freestyle performance. International Journal of Sport Nutrition and Exercise Metabolism, 18, 116-131.

This study investigated the effects of sodium bicarbonate (NaHCO3), caffeine, and their combination on repeated 200-m freestyle performances. Elite male freestyle swimmers (N = 6) ingested sodium bicarbonate (0.3 g/kg), caffeine (6.2 mg/kg), a combination of both, and a placebo on four separate occasions before completing two maximal 200-m freestyle time trials separated by 30 minutes of recovery.

No significant between-groups performance differences were observed in either trial. The drop-off in performance time from the first to the second trial was significantly greater when caffeine was ingested than with sodium bicarbonate or sodium bicarbonate plus caffeine. The ergogenic benefit of taking caffeine alone for repeated 200-m swimming performance is limited. When combined with sodium bicarbonate caffeine's negative impact on repeated maximal exercise performance is reversed.

Implication. Sodium bicarbonate reduces performance drop-off between repeated 200-m freestyle swims much more effectively than caffeine.

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