Effects of post-exercise sodium bicarbonate ingestion on acid-base balance recovery and time-to-exhaustion running performance: a randomised crossover trial in recreational athletes.

This study investigated the effect of post-exercise sodium bicarbonate (NaHCO) ingestion on acid-base balance recovery and time-to-exhaustion (TTE) running performance. Eleven male runners (stature, 1.80 ± 0.05 m; body mass, 74.4 ± 6.5 kg; maximal oxygen consumption, 51.7 ± 5.4 mL·kg·min) participated in this randomised, single-blind, counterbalanced and crossover design study. Maximal running velocity (v-O) was identified from a graded exercise test. During experimental trials, participants repeated 100% v-O TTE protocols (TTE1, TTE2) separated by 40 min following the ingestion of either 0.3 g·kg body mass NaHCO (SB) or 0.03 g·kg body mass sodium chloride (PLA) at the start of TTE1 recovery. Acid-base balance (blood pH and bicarbonate, HCO) data were studied at baseline, post-TTE1, after 35 min recovery and post-TTE2. Blood pH and HCO concentration were unchanged at 35 min recovery ( > 0.05), but HCO concentration was elevated post-TTE2 for SB vs. PLA (+2.6 mmol·L;  = 0.005;  = 0.99). No significant differences were observed for TTE2 performance ( > 0.05), although a moderate effect size was present for SB vs. PLA (+14.3 s;  = 0.56). Post-exercise NaHCO ingestion is not an effective strategy for accelerating the restoration of acid-base balance or improving subsequent TTE performance when limited recovery is available. Post-exercise sodium bicarbonate ingestion did not accelerate the restoration of blood pH or bicarbonate after 35 min. Performance enhancing effects of sodium bicarbonate ingestion may display a high degree of inter-individual variation. Small-to-moderate changes in performance were likely due to greater up-regulation of glycolytic activation during exercise.