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

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.