Ingestion of sodium bicarbonate (NaHCO3) following a fatiguing bout of exercise accelerates post-exercise acid-base balance recovery and improves subsequent high-intensity cycling time to exhaustion.

Abstract

This study evaluated the ingestion of sodium bicarbonate (NaHCO3) on post-exercise acid-base balance recovery kinetics and subsequent high-intensity cycling time to exhaustion. In a counterbalanced, crossover design, nine healthy and active males (age: 23±2 years, height: 179±5 cm, body mass: 74±9 kg, peak mean minute power (WPEAK) 256±45 W, peak oxygen uptake (V̇O2PEAK) 46±8 ml.kg-1.min-1) performed a graded incremental exercise test, two familiarisation and two experimental trials. Experimental trials consisted of cycling to volitional exhaustion (TLIM1) at 100% WPEAK on two occasions (TLIM1 and TLIM2) interspersed by a 90 min passive recovery period. Using a double blind approach, 30 min into a 90 min recovery period participants ingested either 0.3 g.kg-1 body mass sodium bicarbonate (NaHCO3) or a placebo (PLA) containing 0.1 g.kg-1 body mass sodium chloride (NaCl) mixed with 4 ml.kg-1 tap water and 1 ml.kg-1 orange squash. The mean differences between TLIM2 and TLIM1 was larger for PLA compared to NaHCO3 (-53±53 vs. -20±48 s; P=0.008, d=0.7, CI=-0.3, 1.6), indicating superior subsequent exercise time to exhaustion following NaHCO3. Blood lactate [BLa-] was similar between treatments post TLIM1, but greater for NaHCO3 post TLIM2 and 5 min post TLIM2. Ingestion of NaHCO3 induced marked increases (P<0.01) in both blood pH (+0.07±0.02, d=2.6, CI=1.2, 3.7) and bicarbonate ion concentration [HCO3-] (+6.8±1.6 mmo.l-1, d=3.4, CI=1.8, 4.7) compared to the PLA treatment, prior to TLIM2. It is likely both the acceleration of recovery and the marked increases of acid-base after TLIM1 contributed to greater TLIM2 performance compared to the PLA condition.