ABSTRACT
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; °C) (relative humidity ∼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.
Highlights
This is the first time NaHCO3 ingestion has been shown to improve 4-km cycling TT performance in conditions of high ambient heat.
A smaller dose of NaHCO3 (0.2 g.kg−1 BM) is ergogenic in the heat, which is smaller than the dose typically ingested for sports performance (0.3 g.kg−1 BM). This is important, as gastrointestinal discomfort is typically lower as the dose reduces.
This study suggests that the individualised time-to-peak HCO3− ingestion strategy with lower doses of NaHCO3 is an ergogenic strategy in conditions of high ambient heat.
Acknowledgements
We thank the participants and the laboratory technician, Mark Doyle, for their assistance.
Disclosure statement
No potential conflict of interest was reported by the author(s).