Bicarbonate Without the Gut Bomb: Does It Work for Long-Course Racing?

Sodium bicarbonate has been one of the few supplements with solid evidence behind it for decades. It also has a reputation, well earned, for sending athletes running to the toilet. For most triathletes, that combination made it easy to ignore: the proven benefits were in short, very hard efforts, and the side effects seemed especially risky in a race lasting many hours.

Two things have changed that conversation. First, new delivery systems, such as bicarbonate mini-tablets in a carbohydrate hydrogel, appear to cut the gut problems sharply. Second, researchers have started to test bicarbonate in longer and more fatiguing exercise. On 2 October 2026, World Athletics published a news story on a Liverpool John Moores University study in which bicarbonate was taken with carbohydrate during three hours of moderate exercise, followed by high-intensity efforts.

This article explains what bicarbonate does, what the best evidence shows, what the new formats change, and whether there is a realistic case for using it in long-course triathlon. Spoiler: the case is interesting but not yet made.

What sodium bicarbonate does

When you work hard, especially above your threshold, your muscles produce hydrogen ions faster than they can be cleared. The resulting fall in pH is one of several contributors to fatigue during intense exercise.

Your blood contains bicarbonate, a natural buffer that mops up some of that acid. Taking sodium bicarbonate raises blood bicarbonate, which increases the blood's buffering capacity. The theory is that a larger buffer lets hydrogen ions move out of muscle more easily, delaying the point where acidity limits performance.

That mechanism tells you something important straight away. Bicarbonate is most likely to help when acid build-up is a major limiter, which means hard efforts above threshold, not the steady, mostly aerobic work that makes up most of a long-course race.

The ISSN position stand: what's well established

The most useful summary of the evidence is the International Society of Sports Nutrition (ISSN) position stand on sodium bicarbonate, published by Grgic and colleagues in 2021. It reviewed the research across a range of sports and set out ten position statements. The key ones for triathletes are:

• What it helps: doses of 0.2 to 0.5 g/kg improve performance in muscular endurance, several combat sports, and high-intensity cycling, running, swimming and rowing.
• How long the effort is: the effects are mostly established for efforts of about 30 seconds to 12 minutes, both single and repeated bouts.
• Who it helps: the benefits apply to both men and women.
• How much: for a single dose, about 0.3 g/kg is the minimum effective dose and appears optimal. Doses of 0.4 or 0.5 g/kg may not add benefit and may increase side effects.
• When: take a single dose 60 to 180 minutes before exercise.
• Multi-day loading: 0.4 or 0.5 g/kg per day for 3 to 7 days, split into smaller doses with meals, is another option that may reduce side effects.
• Side effects: the most common are bloating, nausea, vomiting and abdominal pain. They vary between individuals, and the position stand describes them as generally low in incidence and severity.
• Placebo: part of the effect appears to be placebo.

Notice what isn't on the list. The position stand doesn't make a claim for long, steady endurance events.

The bigger picture: a meta-analysis of 189 studies

A 2022 systematic review and meta-analysis in Sports Medicine by de Oliveira and colleagues pooled 189 articles with 2,019 participants, covering sodium bicarbonate, sodium citrate and lactate supplements. The main findings were:

• Blood bicarbonate rose by about 5.2 mmol/L on average after supplementation.
• The overall effect on exercise capacity and performance was positive but small, with an effect size of 0.17.
• Sodium bicarbonate was more effective than sodium citrate.
• By duration, effects were found for efforts of 0.5 to 10 minutes (effect size 0.18) and for efforts longer than 10 minutes (0.22).
• Bigger rises in blood bicarbonate (above about 4 mmol/L) were linked to bigger benefits than small rises.

That result for efforts over 10 minutes is worth noting, because it's often assumed bicarbonate only helps short sprints. But "longer than 10 minutes" in this literature mostly means time trials and tests lasting tens of minutes, not five to fifteen hours. The meta-analysis's abstract doesn't break results down by sex.

Inference: an effect size of around 0.2 is small. It can matter in a close race, but it's the kind of gain that a poor night's sleep, a mistimed gel or a few minutes of gut distress could easily wipe out.

The gut problem

For many athletes, the real question isn't whether bicarbonate works but whether they can tolerate it. A dose of 0.3 g/kg is a lot of powder. Taken as capsules or dissolved in water, it reacts with stomach acid and releases gas, and the large sodium load draws water into the gut. The result for some people is bloating, cramping, urgent bowel movements or vomiting.

The ISSN position stand suggests four ways to reduce side effects:

1. Use smaller doses, such as 0.2 or 0.3 g/kg rather than higher.
2. Take it about 180 minutes before exercise, or adjust timing to your own response.
3. Take it with a high-carbohydrate meal.
4. Use enteric-coated capsules, which are designed to pass through the stomach before dissolving.

It also notes that, in the studies reviewed, side effects didn't generally appear to harm performance. That is reassuring for a short time trial in a lab. It's less reassuring for a triathlete who needs to keep eating and drinking for hours afterwards.

The hydrogel approach

The most talked-about recent development is delivering bicarbonate as small tablets inside a carbohydrate hydrogel, a thick gel that forms when the drink mixes with a little water. The commercial product is sold as a "Bicarb System". The idea is that the gel carries the tablets through the stomach with less contact with stomach acid, so less gas is released there.

Gough and Sparks tested this in a 2024 study in Sports Medicine – Open. Twelve well-trained male cyclists took 0.3 g/kg of bicarbonate, either in the hydrogel system or in vegetarian capsules, each with about 40 g of carbohydrate, in a randomised, double-blind crossover design. They stayed at rest for five hours while blood and gut symptoms were measured every 30 minutes.

• Peak blood bicarbonate was 0.95 mmol/L higher with the hydrogel.
• The peak came earlier, at 117 minutes on average versus 156 minutes with capsules, and bicarbonate stayed raised for longer.
• Aggregated gut discomfort was 79 arbitrary units lower with the hydrogel, a large difference. Stomach cramps, bowel urgency, diarrhoea, belching and stomach ache were all reduced.

The authors were clear that the study didn't test performance, and that it was done at rest. Exercise itself changes how the gut behaves.

Does it improve longer time trials?

A second 2024 study, by Shannon and colleagues in the European Journal of Applied Physiology, took the next step. Fourteen trained male cyclists completed 40 km time trials after taking 0.3 g/kg of bicarbonate or a placebo in a carbohydrate hydrogel. The timing of each dose was individualised to when that athlete's blood alkalosis peaked. The trial was randomised, double-blind and crossover, with a familiarisation ride first.

• Time trial performance improved by about 54 seconds with bicarbonate compared with placebo. The standardised effect size was small (0.22).
• Blood bicarbonate was about 5.6 mmol/L higher before exercise and stayed higher throughout.
• Total gut symptoms didn't differ significantly between bicarbonate and placebo, before or after exercise.

A 40 km time trial lasts roughly an hour for trained cyclists, which is far longer than the classic 1 to 10 minute window. It's still a single, hard, continuous effort, done fresh, by men only. It's closer to an Olympic-distance bike leg than to the back half of an Ironman.

The October 2026 World Athletics study

The news that prompted this article came from World Athletics on 2 October 2026. Its story described a study led by Bernardo Norte, a PhD student at the Research Institute for Sport and Exercise Sciences at Liverpool John Moores University, supervised by Dr Julien Louis, in collaboration with the World Athletics Health and Science Department.

According to the World Athletics page:

• The study tested a new energy gel combining sodium bicarbonate and carbohydrate.
• Participants exercised at moderate intensity for three hours, then performed a series of high-intensity efforts to test performance under fatigue.
• The comparison was carbohydrate alone versus carbohydrate plus bicarbonate.
• Adding bicarbonate improved performance after the prolonged exercise, compared with carbohydrate alone.
• Taking bicarbonate during exercise helped limit acidosis, measured from fingertip blood samples.
• Gut discomfort was mild.

The page also said the findings suggest bicarbonate's benefits may extend beyond high-intensity exercise done in a rested state.

What the page didn't report matters just as much. It gave no sample size, no information on participants' sex or training status, no doses or timing, no performance numbers, and no journal reference. TriForward wasn't able to locate the underlying paper, so this article reports only what World Athletics stated. Until the full study can be read, the right response is interest, not action.

Why this is closer to the triathlon question

Even with those caveats, the design is more relevant to triathletes than most bicarbonate research. Long-course races aren't run at a single steady intensity. There are hard moments late in the race: a climb on tired legs, a surge to stay with a group on the run, a final push to the line.

Inference: if bicarbonate taken during long exercise can preserve the ability to make hard efforts late on, it could matter for racing tactics, even if it does little for the steady pace in between. But that's a hypothesis, not a finding. The World Athletics study involved three hours of moderate exercise followed by a high-intensity test, not a full race in which you have to keep moving for the whole time and the outcome is your finish time.

Why long-course racing is different

Several features of long-course triathlon make bicarbonate a harder sell than in a 2,000 m rowing race or a track final.

• The intensity is mostly below threshold. For most of a 70.3 or Ironman, acid build-up isn't the main limiter. Fuel availability, heat, gut tolerance, muscle damage and pacing usually matter more. TriForward's "Why Watts Fade" covers the range of fatigue mechanisms in long events.
• The gut is already under pressure. Long-course athletes need to take in carbohydrate and fluid for hours. In a study of 221 endurance athletes in Ironman, 70.3 and other events, Pfeiffer and colleagues found that a history of gut problems was associated with gut symptoms during races. Adding a large sodium dose to an already stressed gut is a real risk.
• The timing doesn't line up easily. A pre-race dose peaks within a few hours. In an Ironman, the hard moments may come six to ten hours later.
• Heat and dehydration change the picture. No hydrogel or bicarbonate study described here was done in hot, humid race conditions.

The 2026 IRONMAN World Championship in Kona was a reminder of how fragile the gut can be in long, hot racing. TRI247's live report noted that Jelle Van Riel was seen vomiting on the bike on a day commentators described as "really, really humid". That had nothing to do with bicarbonate, but it shows the kind of conditions any new race supplement has to survive.

The sodium load

Bicarbonate isn't only a buffer. It's also a large dose of sodium.

Inference: sodium makes up roughly 27% of the weight of sodium bicarbonate (based on atomic weights). For a 70 kg athlete, 0.3 g/kg is 21 g of bicarbonate, which contains roughly 5.7 g of sodium. That's a large amount in one go, more than many athletes take in across a whole long-course race from drinks and gels.

That has two implications. First, it's a reason for caution for anyone with high blood pressure, kidney or heart problems, or a medical reason to limit salt. Second, it can interact with your race sodium and fluid plan. More sodium isn't automatically better: TriForward's "Salt Tablets Won't Save You" explains why sodium supplements don't prevent hyponatraemia on their own, and "Cramping at Kona" looks at why salt rarely fixes cramp.

Populations: who has been studied

The populations in the key studies are narrow:

• Gough and Sparks 2024: 12 well-trained male cyclists, at rest.
• Shannon and colleagues 2024: 14 trained male cyclists.
• World Athletics–reported study: participant numbers and characteristics not stated.
• The ISSN position stand concludes that the benefits apply to both men and women across the wider literature, but women are a minority in most individual studies.

There are no studies here in triathletes, no studies in a real race, and no studies of running off the bike after bicarbonate. Most participants were trained men in their twenties or thirties, so older age-groupers and women may respond differently, particularly in gut tolerance.

If you want to experiment

The following is drawn from the ISSN recommendations and the studies above. It isn't a protocol, and it isn't advice that you should use bicarbonate.

1. Check that it's safe for you first, especially if you have blood pressure, kidney, heart or gut conditions or take regular medicines.
2. Start in training, not racing, and on a day with nothing important afterwards.
3. Use the lower end of the dose range. The ISSN position stand suggests 0.2 to 0.3 g/kg for fewer side effects, with 0.3 g/kg appearing optimal for performance.
4. Take it with carbohydrate, ideally as part of a meal or in a hydrogel system.
5. Track timing and symptoms. Note when you took it, what you ate, and how your gut felt over the following hours.
6. Repeat it. One good or bad trial tells you little. Responses vary between individuals and from day to day.
7. Match the test to the race. If your goal is a long-course race, test it during a long session that includes hard efforts late on, not just a short time trial.

A long-course scenario

The following is illustrative, not drawn from a case study. An age-group athlete is preparing for a hilly 70.3 and has heard that bicarbonate helps on climbs. They read that 0.3 g/kg works, buy capsules, and take the full dose with breakfast on race morning for the first time.

By the end of the swim, their stomach feels bloated. On the bike, they struggle to take in their gels, and they need two toilet stops in the first half of the run. Any buffering benefit on the climbs is lost many times over.

A better approach would have been to test the product in several long training rides, using the lowest effective dose and a format with better gut tolerance, and to decide honestly whether the gain was worth the risk. For many athletes, the answer will be that a well-practised carbohydrate and fluid plan matters far more.

Common mistakes

• Trying it for the first time on race day.
• Assuming more is better. Higher doses mostly add side effects.
• Using evidence from sprints to justify it in an Ironman.
• Forgetting the sodium. Bicarbonate adds to your race sodium intake.
• Stacking it with other new products, such as caffeine or a new gel, on the same day, which makes it impossible to know what helped or hurt.
• Ignoring your fuelling plan. Bicarbonate isn't a substitute for carbohydrate. See TriForward's "Gut Training" and "90–120g of Carbs an Hour".

What we don't know

• Whether it improves finish times in long-course triathlon. There are no trials in real 70.3 or Ironman races.
• The details of the 2026 Liverpool John Moores study, including sample size, doses and the size of the effect, until the full paper is available.
• How women and older athletes tolerate the new formats. The hydrogel studies described here were in men.
• How it interacts with heat, dehydration and running. Most studies are in cycling, in temperate lab conditions.
• Whether repeated doses during a race are practical, and how they fit with high carbohydrate intakes.

References

• Grgic J, Pedisic Z, Saunders B, Artioli GG, Schoenfeld BJ, McKenna MJ, et al. International Society of Sports Nutrition position stand: sodium bicarbonate and exercise performance. Journal of the International Society of Sports Nutrition, 2021;18(1):61. doi:10.1186/s12970-021-00458-w
• de Oliveira LF, Dolan E, Swinton PA, Durkalec-Michalski K, Artioli GG, McNaughton LR, Saunders B. Extracellular buffering supplements to improve exercise capacity and performance: a comprehensive systematic review and meta-analysis. Sports Medicine, 2022;52(3):505–526. doi:10.1007/s40279-021-01575-x
• Gough LA, Sparks SA. The effects of a carbohydrate hydrogel system for the delivery of bicarbonate mini-tablets on acid–base buffering and gastrointestinal symptoms in resting well-trained male cyclists. Sports Medicine – Open, 2024;10(1):17. doi:10.1186/s40798-024-00684-x
• Shannon ES, Regnier A, Dobson B, Yang X, Sparks SA, McNaughton LR. The effect of sodium bicarbonate mini-tablets ingested in a carbohydrate hydrogel system on 40 km cycling time trial performance and metabolism in trained male cyclists. European Journal of Applied Physiology, 2024;124(12):3671–3682. doi:10.1007/s00421-024-05567-3
• Pfeiffer B, Stellingwerff T, Hodgson AB, et al. Nutritional intake and gastrointestinal problems during competitive endurance events. Medicine & Science in Sports & Exercise, 2012;44(2):344–351. doi:10.1249/MSS.0b013e31822dc809
• World Athletics. Nutrition study highlights performance benefit of sodium bicarbonate and carbohydrate co-ingestion. News, 2 October 2026. worldathletics.org
• TRI247. IRONMAN World Championship Kona 2026 live updates. 10 October 2026. tri247.com