The effects of sodium bicarbonate supplementation on lower-body hypertrophy-type resistance exercise

Benjamin McLean Carr

Abstract

Introduction: A number of studies have demonstrated the ergogenic effects of induced-alkalosis on high-intensity intermittent exercise performance. Purpose: The aim of the present study was to examine the effects of sodium bicarbonate (NaHCO3 ) administration on a high-volume hypertrophy-type resistance exercise regimen for the lower body. Methods: In a double-blind counterbalanced manner, 12 resistance-trained male participants (mean ± SD; age = 20.3 ± 2 yr, mass = 88.3 ± 13.2 kg, height = 1.80 ± 0.07 m), with a minimum of two years of training experience, ingested either 0.3 g kg -1 of NaHCO 3 or calcium carbonate (CaCO3 ) Placebo, divided into four even doses administered every 10 min, with the last dose being consumed approximately 60 min before the initiation of a hypertrophy-type resistance exercise (HRE) regimen for the lower body. The HRE protocol employed multiple exercises [back squat (SQ), inclined leg press (LP), and knee extension (KE)] utilizing four sets each, with 10- to12-RM (∼65- 75% 1-RM) loads and short rest periods ranging from 60-90 s between sets. Exercise performance was determined by total repetitions generated during each exercise, repetitions accumulated throughout the exercise protocol, and a performance test (PT) involving a fifth set of KE to failure utilizing loads of approximately 50% 1 RM. Arterialized capillary blood samples were extracted via fingertip puncture at four time points and subsequently analyzed for pH, bicarbonate concentration ([HCO 3- ]), base excess (BE), and lactate concentration ([Lac - ]) by a portable clinical blood-gas analyzer. Results: Prior to exercise and relative to Placebo ingestion, NaHCO3 significantly elevated pH (mean ± SD; NaHCO3: 7.49 ± 0.02, Placebo: 7.42 ± 0.02, P < 0.05), [HCO3- ] (NaHCO3 : 31.50 ± 2.59, Placebo: 25.38 ± 1.78 mEq l -1 , P < 0.05), and BE (NaHCO3 : 7.92 ± 2.57, Placebo: 1.08 ± 2.11 mEq l-1 , P < 0.05). NaHCO3 administration resulted in significantly more total repetitions (SQ + LP + KE) than Placebo (NaHCO3 : 139.8 ± 13.2, Placebo: 134.4 ± 13.5), as well as significantly greater arterialized-capillary blood [Lac - ] immediately after the exercise protocol (NaHCO3 : 17.92 ± 2.08, Placebo: 15.55 ± 2.50 mM, P < 0.05). There were no significant differences between group PT repetitions (NaHCO3 : 23.8 ± 4.0, Placebo: 22.3 ± 3.7), although overall total repetitions (SQ + LP + NE + PT) remained significantly higher for the NaHCO3 condition (NaHCO3 : 163.7 ± 15.1 Placebo: 156.7 ± 14.5). Conclusions: Administration of 0.3 g kg-1 NaHCO3 resulted in significantly more total repetitions accumulated throughout the exercise regimen. These findings demonstrate ergogenic efficacy for NaHCO3 administration during HRE and warrant further practical investigation into the effects of induced-alkalosis on the adaptations occurring during chronic HRE training.