The Magnitude of the Blood Acid-Base Response, but Not Time to Peak, Is Reliable Following the Ingestion of Acute, Individualized Sodium Citrate

Tinnion, Daniel ORCID: https://orcid.org/0000-0002-3116-0985, Dobson, Ben ORCID: https://orcid.org/0000-0003-0413-878X, Hilton, Nathan ORCID: https://orcid.org/0000-0003-0204-8967, McNaughton, Lars R ORCID: https://orcid.org/0000-0002-3743-3171 and Sparks, S Andy ORCID: https://orcid.org/0000-0003-0910-2225 (2024) The Magnitude of the Blood Acid-Base Response, but Not Time to Peak, Is Reliable Following the Ingestion of Acute, Individualized Sodium Citrate. International Journal of Sport Nutrition and Exercise Metabolism. pp. 1-9. ISSN 1526-484X

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Abstract

Enhanced buffering capacity following sodium citrate (SC) ingestion may be optimized when subsequent exercise commences at individual time-to-peak (TTP) alkalosis (blood pH or bicarbonate concentration [HCO3-]). While accounting for considerable interindividual variation in TTP (188-300 min), a reliable blood alkalotic response is required for practical use. This study evaluated the reliability of blood pH, HCO3-, and sodium (Na+) following acute SC ingestion. Fourteen recreationally active males ingested 0.4 or 0.5 g/kg body mass (BM) of SC on two occasions each and 0.07 g/kg BM of sodium chloride (control) once. Blood pH and HCO3- were measured for 4 hr postingestion. Blood pH and HCO3- displayed good reliability following 0.5 g/kg BM SC (r = .819, p = .002, standardized technical error [sTE] = 0.67 and r = .840, p < .001, sTE = 0.63, respectively). Following 0.4 g/kg BM SC, blood HCO3- retained good reliability (r = .771, p = .006, sTE = 0.78) versus moderate for blood pH (r = .520, p = .099, sTE = 1.36). TTP pH was moderately reliable following 0.5 (r = .676, p = .026, sTE = 1.05) and 0.4 g/kg BM SC (r = .679, p = .025, sTE = 0.91) versus poor for HCO3- following 0.5 (r = .183, p = .361, sTE = 5.38) and 0.4 g/kg BM SC (r = .290, p = .273, sTE = 2.50). Although the magnitude of (and displacement in) blood alkalosis, particularly HCO3-, appears reliable following potentially ergogenic doses of SC, strategies based on individual TTP cannot be recommended.