Sodium Bicarbonate: What It Actually Does, How Much, and Whether It's Worth It

What sodium bicarbonate actually does to fatigue, the dose per kilogram that works, how to avoid the gut problems, and when you should skip it.

Sodium bicarbonate is plain baking soda, the same thing sitting in your kitchen cupboard, just taken in a dose roughly ten times bigger than the spoonful you put in a cake. It belongs to a very short list of supplements with genuinely solid evidence behind them, but only for one narrow type of effort. Here is what it does, how much to take, and whether it is worth anything to you.

What it actually does

When you push an effort lasting from about half a minute to a few minutes at high intensity, your muscle produces energy mostly through glycolysis and accumulates hydrogen ions along the way. Rising acidity interferes with contraction and with enzyme activity, and it is part of that burning sensation right before you fail.

Bicarbonate does not enter the muscle cell and does not neutralise acid inside the muscle directly. It raises bicarbonate concentration in the blood, which creates a bigger gradient between muscle and blood, and that means faster export of hydrogen ions out of the working cell. In practice: you hold pace a couple of seconds longer, or you squeeze out one or two more reps at the end of a set.

The average effect in the research is roughly 1.5 to 2 percent on performance in efforts lasting 1 to 10 minutes. That does not sound spectacular, but in a two-minute race it is two to three seconds, which is the difference between making a final and watching one.

Who it helps and who it doesn't

It makes sense for:

Efforts of 30 seconds to 8-10 minutes: 400 m and 800 m running, 100-200 m swimming, 2000 m rowing, track cycling, combat sports, CrossFit metcons.
Resistance training in the hypertrophy range: 4-5 sets of 8-12 reps at 70-80% of 1RM with 60-90 second rests. This is where people typically get 1-2 extra reps in the third, fourth and fifth sets.
Repeated-sprint sports where recovery between efforts shrinks as the match goes on.

It does not make sense for:

Maximal strength: a single rep at 90-100% of 1RM is not limited by acidity.
Pure alactic sprints under 10 seconds.
Long aerobic efforts over 60 minutes, where glycolysis is not the limiting factor.
Training where technique or motivation is your real ceiling, not metabolism.

Dosing: the actual numbers

The working dose is 0.2 to 0.3 grams per kilogram of body mass. For an 80 kg person that is 16 to 24 grams. The 0.3 g/kg dose gives the strongest effect, and 0.2 g/kg is the lowest dose shown to reliably do something. Going above 0.3 g/kg buys you no extra benefit, only more gut trouble.

Single dose before the effort

Take it 60 to 180 minutes before competing. At 0.3 g/kg most people peak in blood bicarbonate somewhere between 90 and 150 minutes. Take it with 500-700 ml of water (roughly 7-10 ml per kilogram) and with a carbohydrate meal, say 80-120 g of dry rice or pasta for an 80 kg person. Split the total into 3-4 smaller portions spaced 15-20 minutes apart instead of swallowing it all at once.

Multi-day loading

The alternative: 0.4-0.5 g/kg per day, split into 3-4 doses with meals, for 3 to 5 days. Blood bicarbonate stays elevated for 24 hours or more after the last dose, so you do not have to time anything on race day, and the gut usually tolerates it far better. For an 80 kg person that is 32-40 g per day, so about 10 g per dose.

The gut is why most people quit

Drink 20 grams of soda on an empty stomach with a splash of water and there is a good chance you get nausea, bloating, belching or diarrhoea within 30-60 minutes. That outcome costs you far more than the two percent gives you.

What lowers the risk:

Take it with a carbohydrate-rich meal, never on an empty stomach.
Plenty of water, at least half a litre per dose.
Split it into several smaller doses across 45-60 minutes.
Capsules instead of powder stirred into water.
Start at 0.2 g/kg and only go up once you know it sits well.

How much sodium that really is

This is the part people skip. A 24 g dose of sodium bicarbonate carries about 6.5 g of sodium, which is equivalent to roughly 16 g of table salt. The general recommendation for daily sodium intake is around 2 g. For a healthy person taking it occasionally before a competition, this is not a crisis. For someone with high blood pressure, kidney disease or a salt-restricted diet, it is a serious matter.

How to test it on yourself

Pick a test you can repeat: 2000 m on the rower, 5 sets of 10 reps at the same load, or 800 m on the track.
Do it once with nothing, at the same time of day and after the same pre-session meal.
A week later repeat it with 0.2 g/kg taken 120 minutes before, with food and 600 ml of water.
Write down both the result and how your gut felt, on a scale of 1 to 10.
If the gut was quiet, try 0.3 g/kg next time. If it was not, stay at 0.2 or switch to multi-day loading.

One rule with no exceptions: never try it for the first time on competition day. You need at least 2-3 trial runs in training.

Combining it with beta-alanine has a logic to it, since they act in different places, inside and outside the cell, and the effects partly add up. Caffeine can be stacked too, but be careful, because it upsets some people's stomachs on its own.

When to see a doctor

Talk to a doctor before you take any of this if:

You have high blood pressure, heart disease or kidney disease.
You take diuretics, corticosteroids, lithium or heart medication.
You have a stomach ulcer, reflux or inflammatory bowel disease.
You are pregnant or breastfeeding.
You have been prescribed a salt-restricted diet.

Also see a doctor if a dose leaves you with severe or persistent diarrhoea, muscle cramping, swollen legs or an unusual heart rhythm.

The short version

Bicarbonate only helps in efforts of roughly 30 seconds to 10 minutes, by about 2 percent on average.
The dose is 0.2-0.3 g/kg, taken 60-180 minutes before, with food and 500-700 ml of water.
The gentler option is 0.4-0.5 g/kg per day for 3-5 days, with far fewer gut problems.
At 80 kg that means 16-24 g of soda, about 6.5 g of sodium, so be cautious with blood pressure or kidney issues.
Test it in training at least 2-3 times before you rely on it in competition.