Ingestion of Sodium Bicarbonate (NaHCO3) Following a Fatiguing Bout of Exercise Accelerates Postexercise Acid-Base Balance Recovery and Improves Subsequent High-Intensity Cycling Time to Exhaustion

Abstract

This study evaluated the ingestion of sodium bicarbonate (NaHCO3) on postexercise 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 familiarization 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 with NaHCO3 (-53 ± 53 vs. -20 ± 48 s; p = .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 < .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 with the PLA treatment, before TLIM2. It is likely both the acceleration of recovery, and the marked increases of acid-base after TLIM1 contributed to greater TLIM2 performance compared with the PLA condition.

The influence of alkalosis on repeated high-intensity exercise performance and acid–base balance recovery in acute moderate hypoxic conditions

“…This suggests a greater amount of H + buffering occurred during this time, which subsequently facilitated a more substantial recovery of acid–base balance compared to PLA, in support of previous research (Pruscino et al 2008; Gough et al 2017a). Alternatively, the improvement in TT 2 may have been due to the stress on acid–base balance being blunted by NaHCO 3 during TT 1 , as pH, HCO 3 − , and the SID were all greater immediately post TT 1 compared to PLA.…”

“…Both pH and HCO 3 − following SBC treatments were increased prior to TT 2 , such that the absolute change in HCO 3 − from TT 1 to 40 min recovery was over twofold greater compared to PLA (SBC2 + 51%, SBC3 + 55%), whilst the change in the SID was also more superior (SBC2 + 29%, SBC3 + 31%). This suggests a greater amount of H + buffering occurred during this time, which subsequently facilitated a more substantial recovery of acid–base balance compared to PLA, in support of previous research (Pruscino et al 2008 ; Gough et al 2017a ). Alternatively, the improvement in TT 2 may have been due to the stress on acid–base balance being blunted by NaHCO 3 during TT 1 , as pH, HCO 3 − , and the SID were all greater immediately post TT 1 compared to PLA.…”

“…Alternatively, the improvement in TT 2 may have been due to the stress on acid–base balance being blunted by NaHCO 3 during TT 1 , as pH, HCO 3 − , and the SID were all greater immediately post TT 1 compared to PLA. Based on data from Gough et al ( 2017a ), however, it is more likely that the enhancement of the acid–base balance state between TT 1 and TT 2 explains the improvement in the current study, as the authors reported NaHCO 3 ingestion improved a subsequent exercise even when supplementation was after an initial bout of exercise. Moreover, SBC3 elicited a significantly greater magnitude of acid–base balance recovery prior to TT 2 , and change in HCO 3 − during TT 2 compared to SBC2.…”

“…Pruscino et al ( 2008 ) reported a ‘trivial’ to ‘moderate’ benefit in the second bout of a 2 × 200 m freestyle swim (interspersed with a 30 min recovery) following pre-exercise ingestion of NaHCO 3 . It was then later reported that NaHCO 3 ingestion 30 min into a 90 min post-exercise recovery significantly improved subsequent cycling capacity at 100% peak mean minute power by 16.6% (Gough et al 2017a ). Both studies reported that capillary blood pH and HCO 3 − recovery were accelerated and above baseline at the end of the recovery period, whereas the placebo condition failed to fully recover.…”

“…The ingestion of sodium bicarbonate (NaHCO 3 ) has been shown to accelerate post-exercise acid–base balance recovery and subsequent exercise performance (Pruscino et al 2008 ; Zabala et al 2008 , 2011 ; Gough et al 2017a ). Pruscino et al ( 2008 ) reported a ‘trivial’ to ‘moderate’ benefit in the second bout of a 2 × 200 m freestyle swim (interspersed with a 30 min recovery) following pre-exercise ingestion of NaHCO 3 .…”