Does Bicarbonate of Soda Really Improve Endurance?

Bicarbonate of soda can change the chemistry of your blood and, in the right event, improve performance. But calling it an endurance supplement disguises a much more interesting finding: it appears to work best in a narrow window, and even there the benefit is far from guaranteed.

TL;DR

• Bicarbonate really can improve performance. Controlled trials and meta-analyses show small benefits in some high-intensity exercise, particularly efforts lasting roughly 30 seconds to 12 minutes.
• The average effect hides enormous individual uncertainty. A new analysis of 20 studies in team-sport athletes found a small positive overall effect, but its prediction interval stretched from a negative effect to a potentially meaningful benefit.
• Changing the chemistry doesn't guarantee going faster. In 200m swimmers, bicarbonate significantly changed blood bicarbonate, pH and lactate but didn't significantly improve swimming time.
• Cycling results are more convincing. Across 18 placebo-controlled trials, bicarbonate produced small improvements in performance time and a larger improvement in mean power output.
• Continuous running is much less compelling. A 2025 review found a small, statistically non-significant overall effect after accounting for publication bias and gastrointestinal withdrawals.
• Who takes it may matter. Male sex and greater body mass predicted larger effects in the running analysis, although that needs confirmation and much of the literature is male-dominated.
• The stomach can undo the advantage. Effective doses are large, and gastrointestinal symptoms are common enough to matter in competition.

First, What Are We Talking About?

Bicarbonate of soda, baking soda and sodium bicarbonate are different names for the same chemical, NaHCO₃. Baking powder is something else. The same white powder in your kitchen cupboard has been studied for decades as a sports supplement, which sounds improbable until you consider what happens during intense exercise.

When muscles work at very high intensities, the processes supplying energy are accompanied by an accumulation of hydrogen ions and a fall in pH. The old explanation that lactic acid makes your muscles tired is an oversimplification, but acid-base disturbance is part of the environment in which fatigue develops. Taking sodium bicarbonate raises bicarbonate and pH in the blood, increasing extracellular buffering capacity and helping hydrogen ions move out of working muscle, which should in principle let an athlete sustain intense work slightly longer. Sometimes it does, and sometimes is the important word.

The New Study Shows Why the Average Can Mislead

A meta-analysis published in Frontiers in Nutrition on 9 September 2026 provides one of the clearest illustrations. Researchers analysed 20 studies published between 2004 and 2026, involving 241 team-sport athletes and 53 performance effect sizes, and found that sodium bicarbonate produced a statistically significant improvement in high-intensity intermittent performance. The effect was small: Hedges' g was 0.23, with a 95% confidence interval from 0.07 to 0.39. If we stopped there, the conclusion would be simple enough: bicarbonate works, though not dramatically.

The more revealing number is the prediction interval, which ran from −0.22 to 0.68. A confidence interval describes uncertainty around the estimated average effect. A prediction interval asks a different question: given how much the studies differ from one another, where might the true effect plausibly fall in a comparable future study? Here that range stretches from a negative effect to one that could matter. When the researchers restricted the analysis to trained team-sport athletes, the average effect stayed positive at g 0.26, yet the prediction interval widened further, from −0.30 to 0.82.

That captures the bicarbonate story well. On average there appears to be a benefit. It does not follow that every athlete, event or protocol will see one.

The Swimming Result Makes the Point Better Still

If bicarbonate improves performance by altering acid-base balance, you might reasonably expect that successfully changing that physiology would produce a faster result. A meta-analysis of 200m swimming trials shows why that assumption is dangerous.

Sodium bicarbonate had a large, statistically significant effect on blood bicarbonate, with a standardised mean difference of 1.09. Blood pH rose too, at an SMD of 1.02, and blood lactate increased significantly at 0.76. The supplement was doing precisely what the physiological model predicts. The swimmers were not clearly faster: the effect on 200m time was an SMD of 0.26, with a 95% confidence interval running from −0.58 to 1.10, and the result was not statistically significant.

That does not prove bicarbonate is useless for swimming, since the confidence interval is wide and leaves real uncertainty. It demonstrates something more fundamental: a biomarker moving in the expected direction is not the same as a performance outcome improving. Blood chemistry confirms that sodium bicarbonate reached its target; only the stopwatch says whether that mattered.

Cycling Looks More Convincing

The picture is stronger in cycling. A meta-analysis in the European Journal of Sport Science combined 18 randomised placebo-controlled studies and found that bicarbonate improved mean power output with an SMD of 0.42 and performance time with an SMD of 0.22. Both were statistically significant, and heterogeneity was effectively absent, with I² of 0% for both outcomes.

These are not enormous effects, but in competitive sport they do not need to be. The International Society of Sports Nutrition's position stand cites 4km cycling time trials of around six minutes in which bicarbonate improved completion time by roughly five to eight seconds, about 2%. For an occasional cyclist that is irrelevant; in a race decided by fractions of a second it is not. The event also sits inside the window where bicarbonate makes most sense: hard enough and long enough for acid-base disturbance to matter, but not so long that other constraints take over.

It's Not the Endurance Most People Mean

The ISSN position stand concludes that sodium bicarbonate can improve high-intensity exercise, with the best-established benefits in tasks lasting roughly 30 seconds to 12 minutes. That covers middle-distance events, rowing, track cycling, combat sports and repeated efforts in team sports, all of which can create conditions where extracellular buffering might help. It is quite different from running a marathon, because as exercise lengthens, performance depends more on aerobic capacity, glycogen, hydration, heat regulation and pacing, and acid-base disturbance becomes less central.

A 2025 systematic review of continuous running illustrates the distinction. After accounting for participants who withdrew because of gastrointestinal problems and adjusting for publication bias, the pooled effect was an SMD of 0.18, with a 95% confidence interval from −0.01 to 0.36. The result narrowly missed statistical significance at P = 0.06, with no detected heterogeneity, and the authors judged the certainty of the finding moderate. So if by endurance you mean sustained running, the current case for bicarbonate is considerably weaker than it is for a six-minute cycling effort.

It May Matter Who Is Taking It

The same running review contained another interesting result. In meta-regression, male sex and greater body mass were associated with larger performance effects, and when the researchers looked only at the eight male-only studies, the pooled effect became small but statistically significant, at an SMD of 0.40 with a confidence interval from 0.18 to 0.63.

That should not be translated into "bicarbonate works for men but not women". Meta-regression looks for relationships across existing studies rather than testing them directly, and body mass, training status, event and study design can all differ at once. What it highlights is a wider problem in sports nutrition: much of this literature has been conducted in men, so if the response varies between people, a male-dominated evidence base gives an incomplete picture of who benefits. The useful question may eventually be less "does bicarbonate work?" than "for whom, doing what, and using which protocol?"

Then There Is the Stomach

There is an obvious problem with swallowing enough sodium bicarbonate to alter blood chemistry: your gut may object. Doses studied for performance are typically around 0.2 to 0.5g per kilogram of body weight, so a commonly researched 0.3g/kg means 24g for an 80kg athlete. That is a considerable amount of bicarbonate, and reported side effects include nausea, bloating, abdominal pain, flatulence, diarrhoea and occasionally vomiting. In the 2025 running review, gastrointestinal symptoms were reported by 29.5% of participants taking bicarbonate and were more common than on placebo, with some participants withdrawing because of them.

That creates a direct trade-off, because a few per cent of performance is worth little if the athlete starts the race nauseous. Researchers have investigated different doses, formulations and timing strategies, including individualising ingestion around the point at which someone's blood bicarbonate peaks, and using capsules to make large doses easier to tolerate. People also differ in how quickly blood bicarbonate rises after ingestion, which is one plausible reason similar studies disagree: two athletes can take the same dose at the same time and start the race in different physiological states. The practical lesson is simpler. Bicarbonate is not something to try for the first time before an important event.

What This Actually Means

Sodium bicarbonate occupies an unusual position in sports nutrition. The mechanism is credible, it demonstrably changes blood bicarbonate and pH, and meta-analyses show significant performance improvements in some settings, so this is not a supplement built on theory and marketing alone. But neither is it a general endurance enhancer. The strongest case is for high-intensity exercise lasting long enough for acid-base disturbance to become relevant, yet short enough for it still to limit performance, which is why six minutes of hard cycling looks so different from sustained running. Even inside that window the response is not guaranteed: the team-sport meta-analysis found a positive average with a prediction interval that comfortably crossed zero, and the swimming literature shows large changes in blood markers without a detectable improvement in race time. Training status, body mass, sex, dose, timing, event and gut tolerance may all determine whether a theoretical advantage reaches the stopwatch.

Bicarbonate works. The harder question is whether it works for you, in your event, without making you feel worse first.

Frequently Asked Questions

Does bicarbonate of soda improve endurance?

Sometimes, but endurance is too broad a description. The strongest research supports high-intensity exercise lasting roughly 30 seconds to 12 minutes, rather than prolonged events such as marathon running.

Is bicarbonate of soda the same as baking soda?

Yes. Bicarbonate of soda and baking soda are common names for sodium bicarbonate, NaHCO₃. Baking powder is different.

What are the side effects?

Nausea, bloating, abdominal discomfort, flatulence, diarrhoea and vomiting can occur. In one systematic review of running studies, gastrointestinal symptoms were reported by 29.5% of participants taking bicarbonate, more often than on placebo.

Does sodium bicarbonate help running?

The findings are mixed. A 2025 systematic review of continuous running found a small overall effect that was not statistically significant after accounting for publication bias and gastrointestinal withdrawals, though a subgroup of male-only studies produced a significant effect that needs further investigation.

The Bottom Line

Bicarbonate of soda really can be performance-enhancing, but the claim needs boundaries. Its most convincing effects occur during relatively short, very hard exercise rather than the prolonged activity most people picture when they hear the word endurance. Cycling studies show measurable improvements, running research is less convincing, and swimming demonstrates that substantially changing blood chemistry does not necessarily change race time.

The latest team-sport research makes the uncertainty particularly clear: across 20 studies the average effect was positive, while the prediction interval stretched from a negative result to a potentially meaningful benefit. Add a substantial dose and a real risk of gastrointestinal distress, and bicarbonate looks less like a universal performance hack than a highly context-dependent tool. The chemistry is convincing. Whether it makes an individual athlete faster is a different question.

This article is for general information and does not replace individual medical or sports-nutrition advice.