Sodium bicarbonate
Evidence: moderate
Helps short hard efforts (~30 s to 12 min), so it is for track 800 m to 5 km, not the steady marathon. GI distress is the main limiter; widespread elite track use is a real signal.
Not medical advice
This is a general knowledge base, not medical or dietary advice. If you are injured, unwell or weighing up a supplement or a change to your diet, speak to a doctor, physiotherapist or registered dietitian who knows your situation.
Sodium bicarbonate raises the blood’s buffering capacity, helping the body cope with the acidosis of hard, sustained efforts. It is classed Group A by the Australian Institute of Sport and supported by an ISSN position stand (Grgic et al. 2021). For running, its relevance is narrow: it helps the events where buffering is decisive, roughly 800 m to 5 km on the track and final-kick scenarios, and does little for the steady marathon.
The dose is about 0.3 g per kg of body mass, taken 60 to 180 minutes before exercise, or spread over several days as a serial load (Grgic et al. 2021). By raising extracellular bicarbonate it speeds the efflux of hydrogen ions and lactate from working muscle, reducing the drop in intramuscular pH. The ergogenic window is roughly 30 seconds to 12 minutes, and the effect is clearest for repeated high-intensity bouts.
The evidence for continuous running is more equivocal. A 2025 meta-analysis found a negligible effect once dropouts from gastrointestinal distress and publication bias were accounted for (Miller et al. 2025), though that tested steady-paced running rather than the short track efforts where the buffering rationale is strongest. Gastrointestinal distress is the major limiter, affecting around 30% of users, and is managed with smaller doses, earlier timing, co-ingested carbohydrate, or enteric coating (Grgic et al. 2021).
The “pros use it” signal
New delivery products, notably the Maurten Bicarb System, package bicarbonate in a carbohydrate hydrogel to reduce gut upset; their consistent claim is reduced gastrointestinal distress, with performance benefit mixed across small studies. Elite adoption is real and worth weighing: around two-thirds of distance medallists across 800 m to 10,000 m reportedly used such products at the 2023 World Championships ( NBC reporting). That is journalistic and manufacturer-linked rather than peer-reviewed, so it is a directional signal, not proof. But widespread, voluntary adoption by athletes with most to lose is the kind of smoke that often indicates fire, especially for the middle-distance track events the mechanism best fits.
Never debut it on race day
The dose-limiting problem is gastrointestinal: cramping, nausea and diarrhoea in a substantial minority of users. Anyone considering bicarbonate must trial it repeatedly in training first, to find a dose and timing the gut tolerates, before risking it in a race. For most distance runners, whose events fall outside the 30-second-to-12-minute window, the simpler conclusion is that it is not worth the bother at all.