Dose-related Effects of Sodium Bicarbonate Ingestion on Acid-base Balance During Exhausting Anaerobic Exercise

Abstract

1166 Anaerobic exercise causes significant acid-base balance perturbations. It has been suggested that sodium bicarbonate (NaHCO3) may prevent a significant pH drop during anaerobic exercise resulting in performance enhancement. PURPOSE: To determine whether two intake levels of short-term NaHCO3 supplementation alters acid-base balance and performance during an acute bout of anaerobic exercise. METHODS: Twenty-four men (22 ± 1.77 yrs, 77.5 ± 7.8 kg, 1.79 ± 6.6 m, and a VO2max of 51.03 ± 7.53 ml/kg/min) participated in the present study. Subjects were randomly assigned to one of 3 groups (n = 8/group): control (C, sugar-free mixed fruit placebo), moderate NaHCO3 intake (MI, 0.3 gr/kg), and high NaHCO3 intake (HI, 0.5 gr/kg). Participants consumed either placebo or NaHCO3 for 6 days. pH, HCO3, PO2, PCO2, and lactate in arterialised blood as well as mean cycling power were determined prior to and immediately following a Wingate test (before and following the supplementation period). Data were analysed by ANOVA repeated measures. RESULTS: There was a significant increase (p<0.001) in post blood bicarbonate in MI and HI, and the elevation was incrementally related to the dosage. Exercise in C caused a reduction (p<0.05) of pH (7.42 ± 0.01 at rest vs. 7.15 ± 0.02 post-exercise) and PCO2 (mmHg) (39.8 ± 2.3 at rest vs. 34.3 ± 1.9 post-exercise) and an increase (p<0.001) of lactate (mM) (0.9 ± 0.1 at rest vs. 10.9 ± 2.0 post-exercise). Mean power (W/kg) increased (p<0.05) after supplementation in MI (7.36 ± 1.33 vs. 6.73 ± 0.95) and HI (7.72 ± 1.24 vs. 6.69 ± 1.38) with HI being more effective (p<0.05) than MI. After NaHCO3 ingestion, blood lactate (mM) was higher (p<0.05) during exercise in MI (12.3 ± 1.5 vs. 10.3 ± 2.1) and HI (12.4 ± 1.8 vs. 10.2 ± 1.1). pH was significantly (p<0.05) elevated post-exercise when NaHCO3 was ingested (7.305 ± 0.03 vs. 7.198 ± 0.02 in MI and 7.343 ± 0.02 vs. 7.2 ± 0.01 in HI). HCO3 decreased (p<0.05) with NaHCO3 ingestion post-exercise (29.8 ± 3.3 vs. 17.56 ± 2.5 in MI and 19.8 ± 3.2 vs. 32.3 ± 4.1 in HI). PO2 (mmHg) increased (p<0.05) with NaHCO3 consumption post-exercise (113.3 ± 7.7 vs. 93.2 ± 6.9 in MI and 116.7 ± 8.2 vs. 92.7 ± 7.5 in HI) with HI being more effective (P<0.05) than MI. PCO2 declined (p<0.05) with NaHCO3 supplementation post-exercise (42.8 ± 3.3 vs. 36.2 ± 2.9 in MI and 44.2 ± 5.3 vs. 34.8 ± 4.1 in HI) with HI being more effective (P<0.05) than MI. CONCLUSIONS: Short-term NaHCO3 ingestion may be beneficial for protecting against acid-base balance disturbances and improve performance during acute anaerobic exercise. However, it appears that this NaHCO3-effect on acid-base balance and performance is dose-related with higher intakes being more effective.