Hi,

Everything changed at the 2026 Boston Marathon. Some people attributed the fast times to optimal conditions, and that was certainly part of it. Then everything changed again at the London Marathon, with Sebastian Sawe running 1:59:30 and Tigst Assefa setting the women’s-only world record 2:15:41. There was no tailwind in London.

So what connects Boston and London? The equation is simple:

High carb + Bicarb = A New Era.

My prediction is that there will be astonishing feats at almost every major marathon with reasonable conditions in the future. The same goes for the performances of any athlete trying to see what they are capable of, in every endurance discipline.

Here’s what we know so far:

  • Sebastian Sawe (1:59:30 at London) consumed 115 grams of carbs per hour, plus a gel 5 minutes before the start (I’d argue that makes his effective rate 127.5 grams per hour) using Maurten Drink Mix and Maurten gels
  • Yomif Kejelcha (1:59:41 at London) consumed high-carb using Santa Madre products. That included the fascinating Reset Gel with tart cherry that is designed to delay central nervous system fatigue. I just ordered 2 boxes to try them.
  • Charlie Hicks (2:04:35 at Boston) consumed 320 grams of carbs (154 grams per hour) using Science in Sport Beta Fuel gels. I took 36 of those at the Leadville 100. 
  • Holly Archer (2:33 at London) released a case study with Science in Sport showing that her effort levels were lower at 90 and 120 grams per hour (relative to 60 grams per hour), and Louise Small (2:28 at London) consumed 121 grams per hour using Precision Fuel and Hydration gels (Precision has 90 gram big-a$$ gels for long days out). 


Many of these races also involve pre-race sodium bicarbonate (usually Maurten Bicarb, though I have heard of FLYCARB too). At the Glass City Marathon, which is apparently a race that exists, Vinny Mauri came out of nowhere to run a 2:05:53. I immediately went to his Strava, and his second photo is a cat licking a bicarb bowl. He also has a photo of Nomio on the counter.

Mauri doesn’t even have a “pro” badge on Strava. I expect that will change within a few days.

High carb improves performance on the day of the race, but the reason we’re seeing these breakthroughs is that athletes are training with high carb and adapting more readily. It’s such a powerful performance and health improvement in hard training that the signal from high carb is overtaking the signal from past eras where athletes were allegedly cheating (but without high carb). 

That adaptation benefit applies to every athlete in every endurance sport. In cycling, the power numbers of top-10 finishers in the Tour de France before high carb would now be off the back of the peloton. The winner of Paris Roubaix pre-2020 would be disqualified from the 2026 race for being behind the time cut-off. Talk to the coaches and athletes behind the scenes, and they will be honest: It’s (largely) the carbs.

It’s also bicarb. While bicarb is not as universal as high carb, it’s getting close (athletes are less open about using it in many cases). It provides a buffer that reduces acidity during hard training, improving adaptation too. I take it before 100 milers! 

Just try this experiment to see why bicarb is changing the game. Without bicarb, do 15 x 1 minute fast/1 minute float on a set loop. Note how far you get across 30 minutes. Then take bicarb the next time, and see how far you get (you could even randomize it and take bicarb the first time to avoid adaptation effects). I was a bicarb skeptic before accidentally doing this experiment in early 2024, getting 200 meters farther than I had before. You’re reading my writing now because I committed to bicarb then, which led to races that made people care about what I thought more than when I was considered “just” a coach.

I don’t know what every athlete is doing. But when I was at Boston for coaching this year, I wasn’t surprised to see almost every athlete with carbs every 5k and slurping bicarb on the pre-race shuttle. 

It’s a new world. I’d argue that it is a much healthier world too, where hard training and racing creates a build up stress rather than a break down stress. 

Any record more than a year or two old, at any race over 1 hour, across every discipline? High carb + bicarb = bye bye.

- David