Acute and chronic loading of sodium bicarbonate in highly trained swimmers

In the present study, 200-m swim time in highly trained male swimmers was measured on two consecutive days (Trial 1 and Trial 2) and under three conditions [(1) acute loading, AcL; (2) chronic loading, ChL; (3) Placebo, PLA]. No sodium bicarbonate (NaHCO₃) was administered between Trial 1 and Trial 2 under each condition. Blood lactate concentration ([La⁻]), base excess of extracellular fluid (BE_ecf), plasma bicarbonate concentration ([HCO₃ ⁻]) and pH were determined before and after capsule administration as well as at 0, 3, 5, 15 and 30 min after each 200-m swim trial. Swim time was not different among AcL, ChL or PLA for Trial 1 or 2 and we observed no change in 200-m swim time from Trial 1 to 2 under any condition (F = 0.48, P = 0.80). [HCO₃ ⁻], pH and BE_ecf measured after capsule administration was higher during AcL and ChL when compared with PLA (P < 0.05). We did not observe any difference in blood [La⁻] between the three conditions at any stage post-exercise (P > 0.05). The results indicate that acute and chronic loading of NaHCO₃ does not improve 200-m swim time in highly trained male swimmers.