ObjectivesOral sodium bicarbonate intake (NaHCO3) may improve performance in short maximal exercise by inducing metabolic alkalosis. However, it remains unknown whether NaHCO3 also enhances all-out performance at the end of an endurance competition. Therefore, the present study investigated the effect of stacked NaHCO3 loading on sprint performance following a 3-h simulated cycling race. DesignDouble-blind randomized placebo-controlled cross-over study. MethodsEleven trained male cyclists (22.3 (18.3–25.3) year; 73.0 (61.5–88) kg; VO2max: 63.7 (57–72) mlkg−1min−1) ingested either 300mgkg−1 body weight NaHCO3 (BIC) or NaCl (PL). NaHCO3 or NaCl was supplemented prior to (150mgkg−1) and during (150mgkg−1) a 3-h simulated cycling race with a 90-s all-out sprint (90S) at the end. Capillary blood samples were collected for determination of blood pH, lactate and HCO3− concentrations. Analysis of variance (lactate, pH, HCO3−) and paired t-test (power) were applied to compare variables across condition (and time). ResultsNaHCO3 intake improved mean power during 90S by ∼3% (541±59W vs. 524±57W in PL, p=0.047, Cohen’s D=0.28, medium). Peak blood lactate concentration and heart rate at the end of 90S were higher (p<0.05) in BIC (16.2±4.1mmoll1, 184±7bpm) than in PL (12.4±4.2mmoll−1, 181±5bpm). NaHCO3 ingestion increased blood [HCO3−] (31.5±1.3 vs. 24.4±1.5mmoll−1 in PL, p<0.001) and blood pH (7.50±0.01 vs. 7.41±0.03 in PL, p<0.05) prior to 90S. ConclusionsNaHCO3 supplementation prior and during endurance exercise improves short all-out exercise performance at the end of the event. Therefore, sodium bicarbonate intake can be applied as a strategy to increase success rate in endurance competitions.