The effects of sodium bicarbonate ingestion on cycling performance and acid base balance recovery in acute normobaric hypoxia

Abstract

This study investigated the effects of two separate doses of sodium bicarbonate (NaHCO₃) on 4 km time trial (TT) cycling performance and post-exercise acid base balance recovery in hypoxia. Fourteen club-level cyclists completed four cycling TT's, followed by a 40 min passive recovery in normobaric hypoxic conditions (FiO₂ = 14.5%) following one of either: two doses of NaHCO₃ (0.2 g.kg^-1 BM; SBC2, or 0.3 g.kg^-1 BM; SBC3), a taste-matched placebo (0.07 g.kg^-1 BM sodium chloride; PLA), or a control trial in a double-blind, randomized, repeated-measures and crossover design study. Compared to PLA, TT performance was improved following SBC2 (p = 0.04, <i>g</i> = 0.16, very likely beneficial), but was improved to a greater extent following SBC3 (p = 0.01, <i>g</i> = 0.24, very likely beneficial). Furthermore, a likely benefit of ingesting SBC3 over SBC2 was observed (p = 0.13, <i>g =</i> 0.10), although there was a large inter-individual variation. Both SBC treatments achieved full recovery within 40 min, which was not observed in either PLA or CON following the TT. In conclusion, NaHCO₃ improves 4 km TT performance and acid base balance recovery in acute moderate hypoxic conditions, however the optimal dose warrants an individual approach.