Sodium Bicarbonate for Endurance Sport: Marginal Gain or Unnecessary Risk?

Sodium bicarbonate—better known as baking soda—has become increasingly visible in endurance sport (at the elite level). It is not a new supplement, but improved delivery systems and renewed research interest have made more athletes curious about whether it can improve performance.

The short answer is that sodium bicarbonate can help in the right type of event, but it is not a universal performance enhancer and it needs to be tested carefully.

How does sodium bicarbonate work?

Hard exercise increases the production of hydrogen ions within the working muscles. As these accumulate, the environment within the muscle becomes more acidic and the ability to sustain high-intensity work begins to fall.

Sodium bicarbonate increases the blood’s extracellular buffering capacity. In simple terms, it helps the body move and manage some of the acidity produced during intense exercise, potentially allowing an athlete to maintain a demanding effort for slightly longer.

It does not eliminate fatigue or replace good training. It may simply delay one of the factors contributing to fatigue when the intensity is sufficiently high.

Where is it most likely to help?

The strongest evidence supports high-intensity exercise lasting approximately 30 seconds to 12 minutes, together with repeated hard efforts. This includes track intervals, hard cycling efforts, rowing, swimming and repeated surges.

For endurance athletes, the most relevant applications may include:

• Short running, cycling or swimming races

• High-intensity interval sessions

• Repeated climbs or attacks during cycling

• A hard finish after a longer endurance event

• Short-course triathlon

• Events involving repeated changes of pace

The benefit during a steady Ironman or long-distance endurance effort is less certain. However, sodium bicarbonate may still be useful when an athlete needs to produce a hard surge, climb or finishing effort after prolonged exercise.

A 2024 study involving trained male cyclists found that bicarbonate mini-tablets delivered within a carbohydrate hydrogel improved 40-kilometre cycling time-trial performance. This is encouraging, although it does not mean the same result will occur for every athlete or event.

Dose and timing

Research commonly uses approximately 0.2 to 0.3 grams of sodium bicarbonate per kilogram of body mass. For a 70-kilogram athlete, that represents 14 to 21 grams—a substantial amount.

It is normally taken between 60 and 180 minutes before exercise. The best timing varies between athletes because blood-bicarbonate response and gastrointestinal tolerance are highly individual.

More is not necessarily better. Doses above 0.3 grams per kilogram may increase side effects without providing an additional performance benefit.

The biggest problem: gastrointestinal distress

Traditional sodium-bicarbonate loading can cause bloating, nausea, stomach pain, diarrhoea, vomiting and a feeling of excessive fullness. These problems can easily outweigh any potential performance benefit, particularly during running.

Taking bicarbonate with a carbohydrate-rich meal, dividing the dose, using capsules or allowing more time before exercise may improve tolerance. Newer hydrogel and encapsulated products are designed to deliver bicarbonate while reducing stomach discomfort, although they tend to be considerably more expensive than standard bicarbonate.

Test it—never guess

Sodium bicarbonate should never be used for the first time on race day.

Begin by testing it before a controlled training session. Record the dose, timing, food consumed, gastrointestinal response and session outcome. A second or third trial may be needed before deciding whether it is genuinely useful.

The important question is not simply, “Does bicarbonate work?” It is: “Does this protocol provide a repeatable benefit for this athlete, in this type of session, without creating unacceptable side effects?”

It is not suitable for everyone

Sodium bicarbonate provides a very large sodium load. Athletes with high blood pressure, kidney disease, heart problems or other medical conditions should seek medical advice before using it. It may also interact with some medications.

Athletes should use a reputable, batch-tested sports supplement where possible and avoid assuming that ordinary household baking soda is automatically an appropriate race-fuelling product.

Coaches take:

One to watch - a potentially useful marginal gain, not a shortcut.

WIth the current available data, Sodium Bicarbonate appears to support clearance or buffering of lactate, so I see the likely benefit (after testing) in short course racing (< 1 hour). There also appear to be benefits during longer course racing in the elite / professional field, where surges and reactions to attacks and breakaways are more relevant, but less so in the age group racing at a (hopefully!) steady state well below threshold levels. I would argue that it is less important than consistent training, sensible pacing, carbohydrate availability, hydration, sleep and recovery.

Once those fundamentals are in place, bicarbonate may be worth testing within a structured programme. As with every performance strategy, the protocol should be individualised, practised and judged by the athlete’s response—not by marketing claims.