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 high-intensity session starts to burn. Worth understanding properly before you either dismiss it or dump a spoonful in water and hope.
Here's what buffering actually does, what the evidence says on dose, and the trade-off nobody mentions.
The burn isn't lactic acid
First, clear up the myth. That deep ache in your legs on the sled push or the final run isn't "lactic acid" pooling in your muscles. Lactate itself is a fuel your body reuses. The burn comes from a rise in hydrogen ions and the drop in muscle pH that comes with hard anaerobic work.
As pH falls, your muscles' ability to contract forcefully drops with it. That's the fade. Your brain and body pull the brakes to protect you. So the real target isn't lactate, it's managing the acidity that builds alongside it.
That's where buffering comes in. If you can blunt the pH drop, you can hold intensity slightly longer before the fade sets in. We covered the broader 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 the working muscle, a higher level of bicarbonate in the blood helps mop them up and keep the gradient moving in the right direction.
Take extra bicarbonate beforehand and you raise that blood buffering capacity. The muscle can keep clearing acidity a little faster, and you hold power for a little longer. That's the mechanism, and it's well established.
What the evidence shows
Sodium bicarbonate has one of the stronger evidence bases in sports supplementation. The International Society of Sports Nutrition reviewed it and concluded it can improve performance in high-intensity efforts, particularly ones lasting roughly 1 to 10 minutes, and in repeated bouts with short recovery (ISSN position stand on sodium bicarbonate, PubMed).
That profile fits functional fitness and Hyrox well. Repeated high-intensity stations with running in between is close to the exact scenario where buffering earns its keep.
On dose, the research clusters around 0.2 to 0.3 grams per kilogram of body weight, taken roughly 60 to 180 minutes before exercise, with individual timing varying quite a bit (sodium bicarbonate dose-response research on PubMed). For an 80kg athlete, 0.3g/kg works out to around 24 grams. That's a meaningful amount, which brings us to the catch.
The trade-off nobody mentions
Bicarbonate at performance doses is famous for one thing: gut distress. Bloating, cramping, and in some people an urgent and unwelcome dash to the toilet. Take a big dose of baking soda in water an hour before a race and there's a real chance you spend that race managing your stomach instead of your splits.
This is why it stays niche despite the evidence. The performance benefit is real but small, and the gut risk is real and sometimes large.
There are ways to reduce it. Splitting the dose over 30 to 60 minutes, taking it with a carbohydrate-rich meal, and using smaller doses closer to 0.2g/kg all tend to lower the gut hit. Enteric-coated forms that bypass the stomach also help some people. Whatever the method, the rule is the same: never test it for the first time on race day. 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.
Where it earns a look is when you're already well trained, chasing marginal gains, and your event is full of exactly the short, repeated, high-intensity efforts bicarbonate suits. That's a specific athlete. If that's you, it's worth trialling carefully.
We're building products in this space because buffering is genuinely useful for our audience, but only when it's dosed properly and used by the right person. That's the standard we hold anything to. Most supplements are underdosed and oversold. Buffering deserves better than that.
FAQ
Is sodium bicarbonate the same as baking soda? Yes, chemically they're the same thing. The difference is dose, timing, and knowing what you're doing, not the ingredient.
How much sodium bicarbonate should I take before exercise? Research clusters around 0.2 to 0.3 grams per kilogram of body weight, taken 60 to 180 minutes before. Start at the low end, take it with food, and trial it in training first because gut distress is common.
Does it help with Hyrox specifically? The evidence is strongest for repeated high-intensity efforts of around 1 to 10 minutes, which overlaps with Hyrox stations. It's a marginal gain for well-trained athletes, not a fix for aerobic fitness or pacing.
Will it upset my stomach? It can, at performance doses. Splitting the dose, taking it with carbohydrate, and using the lower end of the range all reduce the risk. Test it in training, never for the first time on race day.
Evidence first, honest about the trade-offs. That's how we'd want anyone to talk about a supplement, including us.