Sodium bicarbonate for endurance: what buffering actually does
Sodium bicarbonate is baking soda. It's also one of the most researched performance aids in sport, and it sits right at the heart of what happens when a Hyrox or a hard session starts to burn. It's worth understanding properly before you either write it off or tip a spoonful into water and hope.
Here's what buffering does, what the evidence says on dose, and the trade-off people tend to skip over.
Where the burn really comes from
First, let's clear up a myth. The deep ache in your legs on the sled push or the final run comes from a rise in hydrogen ions and the drop in muscle pH that goes with hard anaerobic work. Lactate itself is a fuel your body reuses.
As pH falls, your muscles lose the ability to contract forcefully. That's the fade. Your brain and body pull the brakes to protect you. So the real target is the acidity that builds alongside lactate.
That's where buffering comes in. Blunt the pH drop and you can hold intensity a little longer before the fade sets in. We covered the bigger picture in our lactic acid buffer guide.
How sodium bicarbonate works
Bicarbonate is an alkaline buffer that lives mainly in your blood, outside the muscle cell. When hard exercise pushes hydrogen ions out of working muscle, more bicarbonate in the blood helps mop them up and keeps them flowing out of the muscle.
Take extra bicarbonate beforehand and you raise that blood buffering capacity. Your muscles clear acidity a little faster, and you hold power a little longer. That mechanism is well established.
What the evidence shows
Sodium bicarbonate has one of the stronger evidence bases in sports supplements. The International Society of Sports Nutrition reviewed it and concluded it can improve performance in high-intensity efforts, especially ones lasting about 1-10 minutes, and in repeated bouts with short recovery (ISSN position stand on sodium bicarbonate, PubMed).
That suits functional fitness and Hyrox well. Repeated hard stations with running in between is close to the exact situation where buffering earns its keep.
On dose, the research clusters around 0.2-0.3g per kilo of bodyweight, taken roughly 60-180 minutes before exercise, and the best timing varies a lot between people (sodium bicarbonate dose-response research on PubMed). For an 80kg athlete, 0.3g/kg is around 24g. That's a lot of baking soda, which brings us to the catch.
The trade-off nobody mentions
At performance doses, bicarbonate is famous for gut trouble. Bloating, cramping and, for some people, an urgent dash to the toilet. Take a big dose in water an hour before a race and there's a real chance you spend the race managing your stomach instead of your splits.
That's why it stays niche despite the evidence. The performance benefit is real and small, and the gut risk is real and sometimes large.
You can reduce it. Splitting the dose over 30-60 minutes, taking it with a carb-heavy meal and using smaller doses nearer 0.2g/kg all tend to ease the gut hit. Enteric-coated forms that pass through the stomach help some people too. Whatever you try, the rule's the same: trial it in training several times before you trust it in a race.
Does it belong in your kit?
Honest answer: for most recreational athletes, it's optional. The gains are modest and the downside is annoying. If your Hyrox time is limited by aerobic fitness, pacing or strength, fix those first. They matter far more.
It's worth a look when you're already well trained, chasing marginal gains, and your event is full of the short, repeated, hard efforts bicarbonate suits. That's a specific athlete. If that's you, trial it carefully.
Buffering is useful for the athletes we make products for, which is why we made Lactic Acid Buffer: 1600mg lactate (as calcium lactate), 1500mg citrulline DL-malate and 1000mg taurine per serving, taken as one scoop a day. Most supplements are underdosed and oversold. Buffering deserves proper doses and honest advice.
FAQ
Is sodium bicarbonate the same as baking soda? Yes, chemically they're the same thing. What changes is the dose, the timing and knowing what you're doing.
How much sodium bicarbonate should I take before exercise? Research clusters around 0.2-0.3g per kilo of bodyweight, taken 60-180 minutes before. Start at the low end, take it with food and trial it in training first, because gut trouble is common.
Does it help with Hyrox specifically? The evidence is strongest for repeated hard efforts of about 1-10 minutes, which overlaps with Hyrox stations. It's a marginal gain for well-trained athletes. Aerobic fitness and pacing still come first.
Will it upset my stomach? It can, at performance doses. Splitting the dose, taking it with carbs and using the lower end of the range all lower the risk. Test it in training well before race day.
Evidence first, honest about the trade-offs. That's how we'd want anyone to talk about a supplement, including us.