Acute Sodium Bicarbonate Supplementation Enhances 10-km Outdoor Track Running Performance in Recreational Female Runners.

Abstract

This study investigated the effects of acute sodium bicarbonate (SB) supplementation co-ingested with a carbohydrate-rich meal on 10-km running performance and gastrointestinal symptoms in recreational female runners under field-based conditions. Twenty-one healthy women (33.6 ± 4.6 years; body mass index 20.8 ± 1.3 kg/m; maximal oxygen uptake 48.6 ± 2.0 ml·kg-1·min-1) completed two 10-km outdoor track running time trials (TTs) in a randomized, double-blind, crossover design. Participants ingested either SB (0.3 g/kg body mass [BM]) or placebo (PLA; 0.03 g/kg BM table salt), together with a standardized carbohydrate-rich meal (1.5 g/kg BM), 90 min before exercise during the same phase of the menstrual cycle. Blood pH, bicarbonate [HCO3-], and [lactate] were measured before, and 1, 3, 5, and 7 min after the TTs; performance time was recorded. Gastrointestinal symptoms were recorded at 30, 60, and 90 min after SB and PLA ingestions. Blood pH (7.47 ± 0.03 vs. 7.42 ± 0.04, p < .001) and [HCO3-] (27.7 ± 1.4 vs. 22.2 ± 1.5 mmol/L, p < .001) were higher at rest and remained elevated postexercise following SB compared with PLA (p < .05 for all time points). TT completion time improved after SB compared with PLA (3,046.1 ± 208.7 s vs. 3,078.4 ± 206.8 s; p = .011). No significant differences in gastrointestinal symptoms scores were observed between conditions (p > .05 for all). In conclusion, acute co-ingestion of 0.3 g/kg of SB with a carbohydrate-rich meal is a practical and well-tolerated strategy to achieve higher resting blood [HCO3-] and pH as well as to improve 10-km TT running performance in recreational female runners.