Dose-response of sodium bicarbonate ingestion highlights individuality in time course of blood analyte responses
- Publisher: Human Kinetics
To defend against hydrogen cation accumulation and muscle fatigue during exercise, sodium 20 bicarbonate (NaHCO3) ingestion is commonplace. The individualised dose-response relationship 21 between NaHCO3 ingestion and blood biochemistry is unclear. The present study investigated the 22 bicarbonate, pH, base excess and sodium responses to NaHCO3 ingestion. Sixteen healthy males (23±2 23 years; 78.6±15.1 kg) attended three randomised order-balanced, non-blinded sessions, ingesting a single 24 dose of either 0.1, 0.2 or 0.3 g.kg-1BM of NaHCO3 (Intralabs, UK). Fingertip capillary blood was 25 obtained at baseline and every 10 min for 1 h, then every 15 min for a further 2 h. There was a significant 26 main effect of both time and condition for all assessed blood analytes (P≤0.001). Blood analyte 27 responses were significantly lower following 0.1 g.kg-1BM compared with 0.2 g.kg-1BM; bicarbonate 28 concentrations and base excess were highest following ingestion of 0.3 g.kg-1BM (P≤0.01). Bicarbonate 29 concentrations and pH significantly increased from baseline following all doses; the higher the dose the 30 greater the increase. Large inter-individual variability was shown in the magnitude of the increase in 31 bicarbonate concentrations following each dose (+2.0-5; +5.1-8.1; and +6.0-12.3 mmol·L-1 for 0.1, 0.2 32 and 0.3 g.kg-1BM) and in the range of time to peak concentrations (30-150; 40-165; and 75-180 min for 33 0.1, 0.2 and 0.3 g.kg-1BM). The variability in bicarbonate responses was not affected by normalisation 34 to body mass. These results challenge current practices relating to NaHCO3 supplementation and clearly 35 show the need for athletes to individualise their ingestion protocol and trial varying dosages prior to 36 competition.
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