The effects of sodium bicarbonate supplementation at individual time-to-peak blood bicarbonate on 4-km cycling time trial performance in the heat

The purpose of this study was to explore the effect of individualised sodium bicarbonate (NaHCO3) supplementation according to a pre-established individual time-to-peak (TTP) blood bicarbonate (HCO3-) on 4-km cycling time trial (TT) performance in the heat. Eleven recreationally trained male cyclists (age: 28 +/- 6 years, height: 180 +/- 6 cm, body mass: 80.5 +/- 8.4 kg) volunteered for this study in a randomised, crossover, triple-blind, placebo-controlled design. An initial visit was conducted to determine TTP HCO3- following 0.2 g.kg(-1) body mass (BM) NaHCO3 ingestion. Subsequently, on three separate occasions, participants completed a 4-km cycling TT in the heat (30 degrees centigrade; degrees C) (relative humidity similar to 40%) following ingestion of either NaHCO3 (0.2 g.kg(-1) body mass), a sodium chloride placebo (0.2 g.kg(-1) BM; PLA) at the predetermined individual TTP HCO3-, or no supplementation (control; CON) . Absolute peak [HCO3-] prior to the 4-km cycling TT's was elevated for NaHCO3 compared to PLA (+2.8 mmol.l(-1); p = 0.002; g = 2.2) and CON (+2.5 mmol.l(-1); p < 0.001; g = 2.1). Completion time following NaHCO3 was 5.6 +/- 3.2 s faster than PLA (1.6%; CI: 2.8, 8.3; p = 0.001; g = 0.2) and 4.7 +/- 2.8 s faster than CON (1.3%; CI: 2.3, 7.1; p = 0.001; g = 0.2). These results demonstrate that NaHCO3 ingestion at a pre-established individual TTP HCO3- improves 4-km cycling TT performance in the heat, likely through enhancing buffering capacity.

Automated summary

This study demonstrated that individualized sodium bicarbonate supplementation based on pre-established time-to-peak blood bicarbonate levels improved performance in a 4-km cycling time trial in heat, likely by enhancing buffering capacity.