The effect of sodium bicarbonate mini-tablets in a carbohydrate hydrogel on prolonged high-intensity cycling performance and metabolism in acute normobaric hypoxia

Abstract

Purpose Hydrogen cation (H + ) accumulation is exacerbated in hypoxia. Sodium bicarbonate (NaHCO 3 ) ingestion can reduce fatigue associated with high-intensity exercise performance by counteracting H + ion accumulation. The present study aimed to determine the effect of 0.3 g·kg − 1 NaHCO 3 mini-tablets in a carbohydrate hydrogel on 40 km cycling time trial (TT) performance in trained male cyclists in acute hypoxia. Methods Fourteen trained male cyclists completed a ramp test to determine VO 2Peak . After, in a randomised, double-blinded, placebo-controlled crossover study, participants completed three 40 km cycling TTs (1 x familiarisation, 2 x experimental) in acute hypoxia (16.7 ± 0.2 FiO 2 ). Each experimental TT followed 90 min after the ingestion of 0.3 g·kg − 1 BM NaHCO 3 or an appearance-matched placebo. Results After NaHCO 3 ingestion, 40 km cycling TT performance was improved by 1.2% in comparison to placebo ( t = 3.84, p = 0.02, g = 0.19). Additionally, NaHCO 3 ingestion raised blood pH ( f = 48.47, p = < 0.001, pη 2 = 0.79) and blood HCO 3 − ( f = 64.13, p = < 0.001, pη 2 = 0.84) pre-exercise and throughout the TT. Aggregated gastrointestinal symptoms (GIS) were minimal, and did not differ between conditions (NaHCO 3 , 110 AU; Placebo, 119 AU; z = 0.38, p = 0.71, r = 0.10). Conclusion The present study suggests that 0.3 g·kg − 1 NaHCO 3 can enhance 40 km cycling TT performance in acute hypoxia, likely a result of improved buffering capacity. Cyclists competing at altitude could consider the ingestion of this form of NaHCO 3 to minimise the deleterious effects of acute hypoxia.

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