Verdict: A proven buffer for hard efforts of 30 seconds to 12 minutes, but the gut side effects mean you must test it in training
Safety: Bloating, nausea, vomiting and stomach pain are common risks; high sodium load
Key takeaways
Sodium bicarbonate buffers acid in the blood and improves high-intensity efforts lasting about 30 seconds to 12 minutes
Studies suggest 0.3 g per kg is the sweet spot, with higher doses adding side effects but not benefit
Gut trouble is the main problem, reduced by smaller doses, taking it with a carb-rich meal, earlier timing or enteric-coated capsules
Sodium bicarbonate is ordinary baking soda, and it is one of the few supplements with solid evidence for performance. It helps very hard efforts, but it is not a VO2max booster, and its reputation for gut trouble is well earned. Here is how to think about it.
What it is
Bicarbonate is the body's main buffer in the blood. During intense exercise, muscles produce hydrogen ions faster than they can be cleared, and the rising acidity contributes to fatigue. Taking sodium bicarbonate raises blood bicarbonate, which helps pull acid out of muscle and delays that fatigue. It is an extracellular buffer, which complements beta-alanine, which increases buffering inside the muscle.
The IOC consensus statement on dietary supplements (Maughan et al., 2018) lists specific buffering agents, alongside caffeine, creatine and nitrate, among the few supplements with good evidence of performance benefits.
Does it raise VO2max?
No. VO2max is set mainly by your heart's output and your blood's oxygen-carrying capacity. Bicarbonate does not change those. It works when you are already near or above your maximum and acid is building up, letting you tolerate that state a little longer.
Does it improve endurance performance?
For short, hard events, yes. The International Society of Sports Nutrition (ISSN) position stand (Grgic et al., 2021) concludes:
- Doses of 0.2–0.5 g/kg improve performance in muscular endurance, combat sports, and high-intensity cycling, running, swimming and rowing.
- Effects are best established for high-intensity tasks lasting 30 seconds to 12 minutes.
- It works in single and repeated bouts, and in both men and women.
- Long-term use before training sessions may enhance training adaptations such as time to fatigue and power output.
- Part of the effect appears to be placebo-driven.
For steady efforts well below threshold, such as a marathon or a long zone 2 ride, acid build-up is not the limiter, so there is little reason to expect a benefit.
How it is used in studies
- Single dose: 0.2 g/kg seems to be the minimum effective dose and 0.3 g/kg the optimum. Higher doses of 0.4–0.5 g/kg add no extra benefit but more side effects. For a 70 kg person, 0.3 g/kg is 21 g of sodium bicarbonate.
- Timing: 60–180 minutes before exercise or competition.
- Multi-day protocol: 0.4–0.5 g/kg a day, split into smaller doses at meals, for 3–7 days before the event. This can avoid taking a large dose on race day.
- Combinations: adding creatine or beta-alanine may produce additive effects, and in the Saunders et al. (2017) meta-analysis, beta-alanine plus bicarbonate gave the largest effect versus placebo. It is unclear whether combining it with caffeine or nitrate adds anything.
Side effects, safety and anti-doping
Gut problems are the main drawback. The ISSN lists bloating, nausea, vomiting and abdominal pain as the most common side effects. Their incidence and severity vary between people and even between days for the same person, and they can wipe out any benefit if they hit during a race. Strategies to reduce them include:
- Using a smaller dose, around 0.2–0.3 g/kg.
- Taking it around 180 minutes before exercise, or adjusting timing to your own response.
- Taking it with a high-carbohydrate meal.
- Using enteric-coated capsules.
Never try it for the first time on race day. Rehearse the exact protocol during hard training sessions.
A performance dose also contains a lot of sodium. This is not medical advice: if you have high blood pressure, heart or kidney disease, follow a low-sodium diet, or take regular medication, talk to your doctor before using sodium bicarbonate. Antacid-style doses are not the same as performance doses.
Sodium bicarbonate is not banned in sport. If you buy it as a sports product rather than plain baking soda, choose third-party tested options such as Informed Sport or NSF Certified for Sport, because the IOC warns that supplements can be contaminated with prohibited substances.
Who might benefit
- Middle-distance runners, rowers, swimmers and track cyclists.
- Combat-sport athletes and people doing repeated sprints or hard intervals.
- Hyrox and similar mixed events with long, intense blocks (see VO2max for Hyrox).
People with sensitive stomachs, or who race long and steady, are less likely to find it worthwhile.
Bottom line
Sodium bicarbonate is one of the best-supported buffers for hard efforts lasting 30 seconds to 12 minutes, with about 0.3 g/kg taken 1–3 hours before. It does not raise VO2max, and gut side effects are the price, so test it carefully in training. Compare it with other options on the supplements page, and for real aerobic gains, train consistently and track progress with the VO2max calculator.
Frequently asked questions
Does sodium bicarbonate improve performance?
Yes, for hard efforts. The ISSN position stand concludes that 0.2 to 0.5 g per kg improves performance in high-intensity running, cycling, swimming, rowing and combat sports, mostly in tasks lasting 30 seconds to 12 minutes.
What are the side effects of sodium bicarbonate?
The most common are bloating, nausea, vomiting and abdominal pain. They vary between people and from day to day, and they can hurt performance if they strike during a race.
How do you avoid stomach problems with sodium bicarbonate?
Use a smaller dose of about 0.2 to 0.3 g per kg, take it around 180 minutes before exercise with a high-carbohydrate meal, try enteric-coated capsules, or split doses over several days before the event.
Does sodium bicarbonate increase VO2max?
No. It buffers acid in the blood during intense exercise and does not change how much oxygen your heart and lungs can deliver.
Sources
- Grgic J, et al. International Society of Sports Nutrition position stand: sodium bicarbonate and exercise performance. J Int Soc Sports Nutr, 2021.
- Maughan RJ, et al. IOC consensus statement: dietary supplements and the high-performance athlete. Br J Sports Med, 2018.
- Saunders B, et al. β-alanine supplementation to improve exercise capacity and performance: a systematic review and meta-analysis. Br J Sports Med, 2017.