Sodium Bicarbonate and the 10K: 32 Seconds Faster in a Trial With 21 Recreational Women
Sodium bicarbonate taken with a carbohydrate-rich breakfast helped 21 recreational female runners finish a 10K 32 seconds faster, according to a trial from Hacettepe University (Ankara) and the University of Exeter published on 23 October in the International Journal of Sport Nutrition and Exercise Metabolism. The result stands out because it comes at a distance, and in a type of runner, where the most recent review found almost no effect.
What was known about sodium bicarbonate in running
The 2021 position stand of the International Society of Sports Nutrition (ISSN) places the effect of sodium bicarbonate in high-intensity efforts lasting between 30 seconds and 12 minutes. That is what our guide to sodium bicarbonate for runners reflects, along with the general dose and precautions.
In 2025, a meta-analysis in the ISSN journal looked at continuous running. It pooled 11 trials with 126 participants, 84% of them men, and tests lasting 1 to 30 minutes, with a median of 4. After adjusting for dropouts due to gut problems and for publication bias, the benefit was negligible and not significant. Studies with men only did show a small effect, and gut symptoms affected 29.5% of people on bicarbonate against 2.6% on placebo.
The trial: 21 women and a 10K on the track
The participants were 33.6 years old on average, with a body mass index of 20.8 and a VO2max of 48.6 ml/kg/min. The design was randomized, double blind and crossover: each woman ran two 10 km time trials on an outdoor track, one after 0.3 g of sodium bicarbonate per kilo of body mass and the other after 0.03 g of table salt per kilo as a placebo.
The supplement was taken 90 minutes before running with a standardized meal of 1.5 g of carbohydrate per kilo, and both trials took place in the same phase of the menstrual cycle. Andrew M. Jones, a physiologist at the University of Exeter, is among the authors.
Results: 32 seconds faster and no extra gut trouble
With sodium bicarbonate the 10K took 3,046 seconds on average (50:46), and with placebo 3,078 seconds (51:18). The gap was 32 seconds, a little over 1%, and it was statistically significant (p = 0.011).
| Measure (mean) | Sodium bicarbonate | Placebo |
|---|---|---|
| 10 km time | 50:46 | 51:18 |
| Resting blood pH | 7.47 | 7.42 |
| Resting blood bicarbonate | 27.7 mmol/L | 22.2 mmol/L |
| Gut symptom score | no difference | no difference |
Blood pH and bicarbonate were already higher at rest and stayed above placebo at all four measurements taken 1, 3, 5 and 7 minutes after the finish. Lactate was measured too, but the abstract does not give the figures.
The runners scored their gut symptoms 30, 60 and 90 minutes after taking the supplement, and there was no difference from placebo at any point. The 2025 meta-analysis counted the share of people with symptoms, while this trial used a symptom score, so the two figures cannot be compared directly. With this protocol, in any case, the stomach was not a problem.
Why it does not match the 2025 meta-analysis
The trial was not designed to explain the gap, but its protocol differs from earlier studies in several ways. The test lasted about 50 minutes, while in the meta-analysis the typical one was 4 minutes and the longest 30. Every runner took the supplement with the same meal per kilo of body mass, one of the strategies the ISSN already suggested to reduce side effects. And the participants were lean women, exactly the profile where the meta-analysis expected less effect, since it linked the benefit to being male and heavier.
A single trial cannot tell which of those factors matters most. It does call for a more nuanced view of the idea that the effect of sodium bicarbonate is limited to efforts under 12 minutes and to men.
What changes for a recreational runner
For the 10K there is now a tested protocol: 0.3 g of sodium bicarbonate per kilo, 90 minutes before, with a breakfast of 1.5 g of carbohydrate per kilo. For a 60 kg runner that is 18 g of bicarbonate and about 90 g of carbohydrate.
One percent of a 50 minute 10K is about half a minute. It is a measurable gain, though small next to what a good plan and even pacing give you, as in the sub 50 10K plan. If you want to try it, do so first in a hard training session, as you would with gels (see train your gut), and check the sodium precautions in the guide. Adding caffeine has not shown an extra benefit, according to this year’s caffeine and bicarbonate meta-analysis.
Limitations
These were 21 women with a specific profile: around 34 years old, lean and trained. We do not know whether the effect holds in less fit women, in recreational men or over the half marathon. The abstract reports group averages and does not say how many runners improved, and the time trials were run solo on a track, without the nerves of a race with a bib.
The full text is behind a paywall, so only the official abstract could be reviewed here, on PubMed and on the journal website. The other two papers cited are the 2021 ISSN position stand and the 2025 meta-analysis on continuous running.
Frequently asked questions
Does sodium bicarbonate work for a 10K?
According to this trial, yes: 21 recreational female runners were 32 seconds faster over 10K on average. Other studies still need to repeat it with more runners and other profiles.
Does sodium bicarbonate work the same in women and men?
The 2025 meta-analysis found a larger effect in men, but 84% of its participants were men. This trial, with women only, did find a significant improvement.
What protocol did the runners use?
0.3 g of sodium bicarbonate per kilo of body mass, 90 minutes before running, with a meal of 1.5 g of carbohydrate per kilo, in the same phase of the menstrual cycle for both trials.
