How Sebastian Sawe Used Bicarb at London Marathon 2026

Everything that can be said about Sebastian Sawe’s Adidas shoes has probably been said. But when it comes to his performance, improvements in super shoes aren’t the whole story.

London Marathon, 2026

Sebastian Sawe crossed the line at the 2026 London Marathon and made history.

Around six hours before that moment when Sawe started his day, he ate a light breakfast, and later started sipping an isotonic drink. But, wedged between those two sources of nutrition, he chugged down a strange goo — something called the Maurten Bicarb System 15 (with the 15 being based on the athlete’s weight).

This gooey “Bicarb” is the very same sodium bicarbonate you’d use for baking a cake, and over the next five hours, it was working through his system. By the time he crossed the finish line, it had given him whatever performance boost it could.

How exactly did it boost Sawe’s performance, if at all? And if it is really just bicarb from the kitchen cupboard, why was he using the special Maurten Bicarb 15 — and why on earth does it cost so much?

A Quick Caveat

At the 2027 London Marathon, I’ll be attempting a world record for the fastest marathon in a suit. Yes, in a suit.

Before diving into the science of bicarb, let’s be clear: bicarb alone isn’t going to get me that world record.

Like shoes, bicarb is just one piece of the puzzle. Sawe didn’t run a sub-2 marathon just because of the shoes, and certainly not because of bicarb.

His performance started with solid training and high mileage, boosted by a multitude of innovations and minor improvements, of which bicarb is just one.

To set a world record, however, I need every little boost I can get. And bicarb may indeed be one of those boosts.

The Science Behind Bicarb

To find out more about what bicarb is and how it potentially helps us run faster, we spoke to Beau Smith from VOOM Nutrition:

"It's been found that bicarb can reduce that acidity in the muscles, which is what kind of gives you that burning sensation if you sprint up a hill or something like that. So, by supplementing with sodium bicarb, essentially you reduce the acidity build-up so you can push that little bit harder."

There are a bunch of potential factors, and it likely has something to do with fatigue buffering, but scientists are still debating the exact mechanisms. All we know for sure is that it does seem to work.

To what extent it works largely depends on the type of activity:

"Rowers were the first kind of to really get on board with it, and their racing's for like sort of five to seven minutes, so it's quite lactic. You've developed quite a lot of lactic acid."

The key point here is duration: 5 to 7 minutes. Research has suggested that supplementing bicarb for efforts raced above lactate threshold from 45 seconds to 8 minutes may produce benefits of a few percentage points, similar to that of caffeine.

One leading coach calls bicarb "gold dust," and it is used by athletes across the board, including world-record 800m runner Keely Hodgkinson, Canadian 800m runner Marc-André Érop — and of course, Sebastian Sawe and world-record half marathon holder Jacob Kiplimo.

Why Are Marathoners Using It?

If the benefits are applicable to shorter-distance anaerobic, lactate-heavy efforts, why are marathon runners bothering with bicarb?

While the benefits on shorter-distance efforts are well documented, more research is needed when it comes to endurance events like the marathon. As it stands, it’s unclear whether there is any benefit at all. However, there are two ways in which it may be helpful:

• In Training: Bicarb can help push harder in VO2 max and threshold workouts, which might improve fitness in training and translate to race day.

• On Race Day: Depending on how fast you are, bicarb can potentially still be in your system to give you a boost in the “last push” of the marathon — say, the last 10K — when the race sways into anaerobic, lactate-heavy territory.

That is undoubtedly the logic that has driven Sawe, Kiplimo, and other marathoners to try out bicarb on race day.

Kitchen Bicarb vs. Commercial Systems

Why buy these special products like the Maurten Bicarb system? Isn’t this just the same cheap bicarb you can buy at the supermarket? Beau Smith explains:

"It could be quite similar, yeah. You know, raid your mother's baking cupboard or something like that... the thing we've done slightly different here is we've put it in a capsule. So that’s time-released; it'll take about two hours to break down in the body, so into the stomach and towards the small intestine.

Because one of the downsides to sodium bicarb is it can, in some people, cause a bit of gastro upset—bit of feeling a bit bloated or feeling a bit sick. The capsules get that further into the body and towards the small intestine before they break down and release the bicarb."

Athletes have been experimenting with bicarb as a supplement since at least the 1980s, but it was largely sidelined due to these stomach issues. Then came Maurten’s Bicarb System in 2023, using a proprietary “hydrogel” that lets the bicarb pass through the stomach without reacting to stomach acid, avoiding gastro problems.

Risking an upset stomach on race day isn’t worth it, so biting the bullet on a specialized product is usually the safer choice.

Should You Use It on Race Day?

Bicarb has a limited performance window — roughly 4 to 4.5 hours — with peak effect around 45 to 60 minutes after ingestion. The question isn’t whether it works, but whether it is still in your system when you actually need it.

• Short, High-Intensity Events (45s – 8m): The benefits are well-supported by science and anecdotal evidence.

• Marathons (Under 4 hours): If you are finishing in under 4 hours, there is a realistic chance the effects overlap with late-race surges and the hardest part of the race, offering a marginal edge in the final push.

• Marathons (Over 4 hours): The timing window likely passes before you reach that critical high-intensity phase over your lactate threshold, making a practical benefit much less likely.

For those planning to try it, general dosing guidelines recommend 300 mg per kg of body weight, taken 1–2 hours before exercise (ideally after a light meal or snack), or using structured options like Maurten where portions are pre-measured.

That’s the strategy for race day at the 2027 London Marathon, suited and booted. Hopefully, the bicarb does its job without any unwanted side effects. Stay tuned for more updates on the suit world record attempt as training progresses.