Abstract
Introduction & PurposeSodium bicarbonate (NaHCO3) is widely used to enhance buffering capacity during high-intensity exercise. However, the negative effects of acidosis, as well as the influence of NaHCO3, remain questionable and controversial. This study aimed to investigate the effect of NaHCO3 supplementation on performance parameters derived from a 3-min all-out cycling test (3MAOT).
MethodsTwelve well-trained male triathletes (age: 27±5.6 years, V̇O₂peak: 60±8 mL∙min-1∙kg-1) volunteered for this double-blinded placebo-controlled study. Subjects were required to visit the laboratory at four occasions: (1) to determine their individual peak [HCO3-] following the ingestion of 0.3 g/kg body mass NaHCO3; (2) to determine V̇O₂peak, maximal aerobic power (MAP) and power output associated with the first ventilatory threshold using a graded exercise test and to familiarise with the 3MAOT (Burnley et al., 2006; Vanhatalo et al., 2007); (3) and (4) to perform the 3MAOT under both experimental conditions (NaHCO3 and microcrystalline cellulose/isomaltulose placebo) in a randomised and alternating order to determine work above end power (WEP) and end power (EP). Respiratory gases were measured to analyse V̇O₂peak and V̇O₂-on-kinetics, and blood lactate samples were collected prior and after the 3MAOT. Blood gas analysis was performed to assess pH and [HCO3-] using capillary blood samples. Nutrition, fluid intake, and capsule ingestion were standardised with individually timed ingestion (125±24 min prior) (AIS, 2025). Gastrointestinal symptoms were assessed using a questionnaire. Trials were separated by >48h. Paired-samples t-tests were used to compare WEP and EP variables between conditions. A two-way repeated-measures ANOVA was used to evaluate blood parameters. Effect sizes were calculated using Cohen’s d and .
Results
All data were normally distributed. No significant differences were found for WEP (p=0.513, d=0.20) and EP (p=0.789, d=0.08) as shown in Figure 1. Significant time x condition interactions for [HCO3-], pH, and maximal [lactate] following NaHCO3 ingestion (all at p0.050; <0.01<<0.59). No notable gastrointestinal symptoms were reported following NaHCO3 ingestion.
DiscussionNaHCO3 did not improve short-time all-out performance at group level in athletes. However, large interindividual variation suggests the presence of responders and non-responders to NaHCO3. The increase in [lactate] in response to NaHCO3ingestion may indicate increased glycolytic contribution or altered clearance kinetics, but this potentially enhanced glycolytic activity did not result in a significant performance improvement. NaHCO3 did not alter V̇O₂-on-kinetics, suggesting no effect on temporal changes of oxidative metabolism at exercise onset.
ConclusionBased on the present results, the intake strategy of 0.3 g/kg of NaHCO3 can be considered a practical and well-tolerated strategy based on gastrointestinal symptom assessment. From a practical perspective, it appears most appropriate to assess the effects of NaHCO3 on an individual basis due to the observed interindividual variation in performance changes. Similarly, the results suggest that a general recommendation for improving short time endurance performance using NaHCO3 cannot be made even though physiological parameters such as pH, [HCO3-] or [lactate] indicate increased buffer capacity.
References
AIS. (2025) Sodium Bicarbonate Group A (AIS Sports Supplement Framework). Australian Institute of Sport. Retrieved 18.05. from https://www.ausport.gov.au/ais/nutrition/supplements/group_a/performance-supplements2/bicarbonate
Burnley, M., Doust, J. H., & Vanhatalo, A. (2006). A 3-min all-out test to determine peak oxygen uptake and the maximal steady state. Medicine and Science in Sports and Exercise, 38(11), 1995-2003. https://doi.org/10.1249/01.mss.0000232024.06114.a6
Vanhatalo, A., Doust, J. H., & Burnley, M. (2007). Determination of critical power using a 3-min all-out cycling test. Medicine and Science in Sports and Exercise, 39(3), 548-555. https://doi.org/10.1249/mss.0b013e31802dd3e6