Key Takeaway
Sodium bicarbonate acutely improves muscular endurance in both small and large muscle groups but has no significant effect on maximal muscular strength.
Summary
This systematic review and meta-analysis evaluated the effects of acute sodium bicarbonate (NaHCO3) supplementation on muscular strength and muscular endurance. The authors distinguished between these two distinct outcomes, as prior reviews had often combined them, obscuring the specific effects on each.
The meta-analysis found that NaHCO3 supplementation significantly improved muscular endurance, measured as the number of repetitions performed to failure at a given load. This benefit was observed for both small muscle group exercises (e.g., bicep curls) and large muscle group exercises (e.g., squats, leg press). The enhanced endurance aligns with the buffering mechanism, as repeated submaximal contractions progressively accumulate hydrogen ions that NaHCO3 helps neutralize.
In contrast, maximal muscular strength (1RM or similar measures) was not significantly affected by NaHCO3 supplementation. This makes physiological sense, as single maximal efforts do not generate sufficient metabolic acidosis to benefit from enhanced buffering capacity. The findings provide important practical guidance: NaHCO3 is useful for high-rep resistance training but should not be expected to improve maximal strength.
Methods
- Systematic search across multiple databases for RCTs comparing NaHCO3 to placebo
- Separate meta-analyses for muscular strength and muscular endurance outcomes
- Subgroup analyses by muscle group size (small vs. large)
- Risk of bias assessment and sensitivity analyses
- Effect sizes calculated as standardized mean differences
Key Results
- Significant improvement in muscular endurance (reps to failure) with NaHCO3
- Benefits observed for both small and large muscle group exercises
- No significant effect on maximal muscular strength (1RM)
- Typical dosing in included studies: 0.3 g/kg taken 60-180 min pre-exercise
Limitations
- Relatively small number of studies, particularly for strength outcomes
- Heterogeneity in exercise protocols, dosing timing, and muscle groups tested
- Most participants were trained males, limiting generalizability
- Blinding challenges due to taste and GI effects of NaHCO3