Sodium bicarbonate supplementation improves severe-intensity intermittent exercise under moderate acute hypoxic conditions

Abstract

Acute moderate hypoxic exposure can substantially impair exercise performance, which occurs with a concurrent exacerbated rise in hydrogen cation (H+) production. The purpose of this study was therefore, to alleviate this acidic stress through sodium bicarbonate (NaHCO3) supplementation and determine the corresponding effects on severe-intensity intermittent exercise performance. Eleven recreationally active individuals participated in this randomised, double-blind, crossover study performed under acute normobaric hypoxic conditions (FiO2% = 14.5%). Pre-experimental trials involved the determination of time to attain peak bicarbonate anion concentrations ([HCO3−]) following NaHCO3 ingestion. The intermittent exercise tests involved repeated 60-s work in their severe-intensity domain and 30-s recovery at 20 W to exhaustion. Participants ingested either 0.3 g kg bm−1 of NaHCO3 or a matched placebo of 0.21 g kg bm−1 of sodium chloride prior to exercise. Exercise tolerance (+ 110.9 ± 100.6 s; 95% CI 43.3–178 s; g = 1.0) and work performed in the severe-intensity domain (+ 5.8 ± 6.6 kJ; 95% CI 1.3–9.9 kJ; g = 0.8) were enhanced with NaHCO3 supplementation. Furthermore, a larger post-exercise blood lactate concentration was reported in the experimental group (+ 4 ± 2.4 mmol l−1; 95% CI 2.2–5.9; g = 1.8), while blood [HCO3−] and pH remained elevated in the NaHCO3 condition throughout experimentation. In conclusion, this study reported a positive effect of NaHCO3 under acute moderate hypoxic conditions during intermittent exercise and therefore, may offer an ergogenic strategy to mitigate hypoxic induced declines in exercise performance.

Effects of daily ingestion of sodium bicarbonate on acid-base status and anaerobic performance during an altitude sojourn at high altitude: a randomized controlled trial

“…The primary finding of the study was that chronic NaHCO 3 ingestion had a considerable impact on acid-base balance, which resulted in a higher alkalotic state; however, chronic NaHCO 3 ingestion did not significantly influence PTSR-related performance outputs and associated physiological responses. A higher alkalotic acid-base balance prior to exercise under hypoxic conditions has been reported to be related to higher performance output and higher maximum blood lactate values after highintensity exercise [11,16,19]. The suggested mechanism underlying the increased [H + ] buffering from intramuscular to extramuscular compartments may lead to improved protection of intramuscular pH and increased anaerobic energy provision and glycogen utilization [16,50].…”

“…Several recent studies reported increased or constant anaerobic exercise performance during acute altitude exposure in hypoxic chambers following supplementation with alkalizing agents prior to exercise [11,16,19,[22][23][24]. All these studies analyzed the effects of bicarbonate supplementation on different aspects of exercise performance under acute hypoxic conditions (between 15 min and 4 h of altitude exposure).…”

“…Feriche Fernandez-Castanys et al [22], Hauswirth et al [23], and McLellan et al [24] all described increased or constant exercise performance under acute altitude conditions in hypoxic chambers compared with sea-level performance in subjects receiving alkalizing agent supplements prior to exercise. In addition, Deb et al [11,19] and Gough et al [16] reported positive effects of NaHCO 3 under acute moderate hypoxic conditions at simulated altitude during intermittent and repeated high-intensity exercise. They conclude that NaHCO 3 ingestion may offer an ergogenic strategy to mitigate hypoxia-induced declines in exercise performance.…”

“…However, while the results of some studies have suggested that significant increases in [H + ] may impair subsequent exercise performance by reducing the capacity for muscle force production [16,17], the results of other studies suggest that exercise performance may be unaffected by disturbances in acid-base balance [18]; thus, there remains no consensus in the literature regarding the roles of acid-base status in anaerobic exercise performance and skeletal muscle fatigue. In addition, it has been suggested that the relative increase in glycolytic flux under hypoxic conditions increases [H + ] production, which may be the underlying mechanism for the beneficial effect of NaHCO 3 ingestion under hypoxic conditions [16,19]. Furthermore, the removal of [H + ] may be inhibited and the blood [HCO 3 − ]-buffering capacity may be reduced [16,19], due to the proposed lower [HCO 3 − ] concentrations present under hypoxic conditions [8].…”

“…In addition, it has been suggested that the relative increase in glycolytic flux under hypoxic conditions increases [H + ] production, which may be the underlying mechanism for the beneficial effect of NaHCO 3 ingestion under hypoxic conditions [16,19]. Furthermore, the removal of [H + ] may be inhibited and the blood [HCO 3 − ]-buffering capacity may be reduced [16,19], due to the proposed lower [HCO 3 − ] concentrations present under hypoxic conditions [8].…”