Individual and Combined Effects of Sodium Bicarbonate and Sodium Citrate Supplementation on High-Intensity Exercise Performance in Highly Trained Female CrossFit Athletes

Purpose: This study compared the ingestion of a matched dose (0.3 g·kg −1 BM) of enteric-coated sodium bicarbonate (SB), sodium citrate (SC), and both combined (SBC) on high-intensity exercise performance using a time-to-peak ingestion strategy. Methods: Ten trained female CrossFit athletes completed four 6-km cycling time trials after consuming either SB, SC, SBC, or a placebo (PLA) in enteric-coated capsules. Blood acid–base balance was measured preingestion, preexercise, and postexercise. Results: Preexercise blood was significantly higher in the SB trial compared with the SC (+2.3 [1.8] mmol·L −1 , P = .003, g = 1.2) and PLA (+6.5 [1.1 mmol·L −1 , P < .0005, g = 2.5) trial. Performance time was faster with SB trials when compared with SC (−11.6 [8.0] s, P = .01), SBC (−17.2 [9.1] s, P = .001), and PLA (−21.5 [14.5] s, P = .007), with no significant difference between SC (mean difference [MD] = 9.9 s, P = .94) and SBC (MD = 4.3, P = 1.0) when compared with PLA. Blood lactate concentration was significantly greater in the SB trial compared with the placebo (MD = 2.4 [2.8] mmol·L −1 , P < .001). Preexercise gastrointestinal symptom scores were higher with SB when compared to PLA (MD = 2.4 [3.2] arbitrary units, P = .04) and SC (MD = 2.2 [2.7], P = .032). Conclusion: Ingestion of 0.3 g·kg −1 BM of SB improved extracellular buffering capacity when compared with SC and PLA, allowing exercise performance improvements.