Where Performance Becomes System: Engineering, Physiology, and the Slow Dissolution of the Two-Hour Wall

Michele Fossi:

For Maurten, that historical moment must have felt something like being inside NASA's Mission Control when Apollo 12 landed on the Moon. I can only imagine the atmosphere in the company's office the moment it became clear one of their athletes had broken the two-hour barrier!  Were you there on Sunday?

Josh Rowe:

I wasn't in the office, actually — but I heard it was insane there! For me, the day was its own kind of insane. I'd flown in to London on the Wednesday before, the moment Sabastian landed, to be on hand through the build-up. Maurten wasn’t a partner of the London Marathon, which meant we didn’t have the same access this time; at Berlin and other races we partner with, I'd basically shadowed Claudio Berardelli, Sabastian's coach, right up to the start gun. Here, that wasn't an option.    

So my wife and I walked down to the finish line, sat in the park with our laptops, and watched the race unfold. A colleague joined us, then a small crowd gathered around us — and it turned into this magical moment. I'm still processing it. Honestly, I couldn't tell you exactly what happened in the race itself, because I was too busy taking splits, recording each kilometre, doing data science in real time as the numbers came in. The last 10K — really from 30K onwards — is a blur in my memory.   

MF:

London delivered three extraordinary performances in a single race — Sawe's record, plus Kejelcha and Kiplimo. How do you explain that?

JR:

Several things came together. London is a fast course — Paula Radcliffe set the women's world record here — but what makes it special is the quality of the field. It's a real race. We had Sawe, Kejelcha, Kiplimo, Kipruto, and Tola — the full elite roster.

As in boxing, where the best often don't face each other for reasons unrelated to the sport, marathon's top runners don't always end up at the same start line. London makes it happen — and that's why these extreme performances become possible.   

The weather cooperated — last year it was hot, this year stable — and the pacers, Andrew and Dennis, executed beautifully. They went through halfway in 60:28, two seconds inside the projected 60:30. Textbook. The plan was to reach 30K, at which point Sabastian moves into his best phase. We expected Kiplimo to push him at the end, but Kejelcha had an extraordinary race, and the two fed off each other. There's a London saying: when you wait for a bus, they all come at once. Two men under two hours, Kiplimo under the previous world record, plus a women's world record. A perfect storm.

MF:

In an interview published in our issue #2, your colleague Herman Reuterswärd — Maurten's Chief Brand Officer — walked me through what he called the

  "marginal gains era": the moment, around 2017, when running stopped being about "just training hard" and became a science of accumulating small technological gains. Nike's carbon-plated shoes and Maurten's first hydrogel drink were, in his telling, the twin pillars of that shift — the carbon plate alone showing that a 4% improvement in marathon times was possible from technology, not training. Two years on, with Sawe now under two hours, what slice of this victory does Maurten claim?

JR:

Nutrition plays a big role, both on race day and in training. Take it back to 2016-2017 — when Maurten first appeared, around Nike's original Breaking2 attempt — nutrition was beginning to be recognised as important, but scientific recommendations for runners were extrapolated from cycling research. That created a paradox: when athletes tried to hit those high-carb intakes, they got severe GI issues. They knew they needed to fuel, but at very high risk of stomach problems compromising performance.

MF:

 That window — 2015 to 2019 — was the exact focus of your PhD. How did you stumble into Maurten?

JR:

I was studying carbohydrate metabolism strategies for marathon and endurance runners. My data confirmed that high-carb intake could deliver significant performance gains, but the GI risk cancelled out most of them. I was about to start a third study — a gut training protocol — when I watched the Breaking2 attempts. A few days later, I heard about a small Swedish company called Maurten. No real product yet, just a flimsy website and some bold claims about a high-concentration carbohydrate drink that mitigated GI issues. To me, it sounded like the holy grail. I assumed it was clever marketing. But once I spoke with athletes already involved, and looked into the hydrogel mechanism, I realised there was something real there.

MF:

And once you went into hydrogel research yourself, what did you find?

JR:

It confirmed everything: yes, you can reach those aggressive carbohydrate intakes, and yes, you can reduce GI issues. The technology was real. In that post-Breaking2 period, we saw a big influx of fast marathon times — Kipchoge, Bekele's 2:01, just two seconds off the world record. But Maurten arrived alongside the carbon-plated shoes, and while they definitely played a big part, the shoes got the glory. Maurten was small, with no voice. Over the last ten years, though, there's been a quiet transition — within the elite performance community and among coaches, nutrition advances are now recognised as a significant factor. Without the hydrogel technology and how athletes now consume carbohydrates, the fuelling strategy we built with Sabastian would have been almost impossible. 

MF:

Quickly for readers: the core idea of the hydrogel is to encapsulate the carbs and bypass the stomach. But you also pair sugars — glucose with fructose. Why?

JR:

Exactly. We use multiple transportable carbohydrates — glucose plus fructose, or maltodextrin plus fructose. They allow high intakes without saturating the absorption transporters. Think of a funnel: pour glucose alone in fast enough, and it overspills. That's where GI issues come from — carbs stay in the stomach, and the body either expels them through vomit or rushes them out as diarrhoea. By combining glucose and fructose, you use two separate transporter pathways. You're effectively widening the funnel.    

MF:

And the hydrogel itself — what's it doing that traditional sports drinks didn't?

JR:

JR: The hydrogel is pH-sensitive, and the technology comes from medicine — it's a drug delivery system. The stomach is the most volatile environment in the body, designed to destroy bacteria and process whatever you ingest. Traditional sports drinks are acidic, so when you pour one into an already acidic stomach, you get a volcanic reaction. Maurten's drink hits the acidic stomach and forms a three-dimensional structure — the hydrogel — that encapsulates the carbohydrates. The stomach doesn't recognise carbs are inside, so the hydrogel passes through to the small intestine, where the pH shifts, the gel degrades, and the carbs are released for absorption. Pre-Maurten, every major marathon had sick buckets prepared at the finish line. They're gone now. 

MF:

Now we're inside the human body — let's go inside Sabastian's specifically. You've been observing him in Kenya for years. How did it start?

JR:

Three years ago. We have routine visits to Kenya at Maurten — once or twice a year, to spend time with selected groups and run testing during sessions. I remember the first time I really met Sabastian. We did a 30K run with Claudio's group, measuring heart rate, core temperature, and blood data pre- and post. Sabastian gave me his heart rate monitor back, and it was completely dry. I was confused — had he even worn it? All the other monitors were soaking wet, dripping. I checked the data on the laptop — yes, he'd worn it. I went to Claudio and asked, "Who is this guy?" Claudio gave me his big smile and said, "That's Sabastian Sawe. He's special."                    

MF:

And what have you been seeing since?

JR:

My involvement has grown — from one or two visits a year to six visits last year. Sabastian trains in a group that includes Benson Kipruto (Olympic bronze in Paris, sub-2:02 in Tokyo, bronze in Boston a few weeks ago), Cyprian Kotut, Amos Kipruto, Andrew Rotich, and Evans Chebet — world-class athletes, several with major marathon wins. And Sabastian, in every dataset we collect — heart rate, core temperature, you name it — is the outlier. A step above the rest. We're talking about athletes with Olympic medals. The last couple of years have been about trying to understand him: what are his limitations? How do we train and optimise an athlete whose numbers keep rewriting the data we already have?

MF:

Can you give a concrete example of how Maurten built Sabastian's specific protocol — something that goes beyond standard guidelines?

JR:

One of our key techniques over the last couple of years has been 13C stable isotope analysis. It tells us how much of the carbohydrate Sabastian is drinking his body actually metabolises. Normally, it's a lab technique — expensive, confined to controlled environments. But there's no proper lab in Kenya, so we developed protocols to take it into the field. We label carbohydrates with 13C — a rare isotope, still glucose, still fructose, but with a tracer signature, meaning we can trace it in the breath. Sabastian runs his long sessions with the labelled carbohydrate drink, we collect his exhaled air in small bags, and the CO2 analysis tells us exactly how much he's oxidised. That tells us how to optimise his intake — both for gut training and race day. We started gradually. On Sunday, he ran the marathon at 115 grams of carbohydrate per hour, plus bicarb. That's cyclist territory, not runner territory.

MF:

Are we reaching a point where we should be asking whether this is doping, or at least a grey area? You're playing with what the body can metabolise. Will regulators have to step in?  

JR:

 It's different. We're not adding any active intervention that could cause harm, or that counts as a significant performance benefit on top. What we're doing is taking generic nutritional recommendations and personalising them to the athlete. It's like a training programme: take a generic one off a website to run a 3-hour marathon — it doesn't account for your physiology, your commitments, your individual needs. We do the same with nutrition, and not just on race day — we optimise his training nutrition as a whole. Training is about creating a stimulus; you want the maximum compound effect. Align quality nutrition

 with quality training, and that effect compounds over weeks, months, and years. After a day or two, nothing. Over months and years, it becomes a major performance gain. That's where we are.

MF:

So in 2026, training for the marathon also means training the gut. It's no longer just muscles and lungs.

JR:

 Exactly. Sabastian has to ingest carbs at race intensity — that's the priority. Most everyday runners take a couple of gels every 20-40 minutes on a slow long run; on race day, when intensity and intake frequency both jump, it's a complete surprise to the body. So we run a gut training protocol. When Sabastian runs at 2:50 per kilometre, blood diverts from the stomach to the working muscles — natural physiological prioritisation — and the stomach operates at lower capacity. Throw carbs into a stomach with reduced blood flow, and you trigger GI issues. The hydrogel helps deliver carbs through a low-capacity stomach, but you still need to practise ingesting at race pace. You don't go from zero to 40K in week one of a 12-week cycle — you build gradually. Same logic with nutrition: gut training shouldn't compromise the training stimulus itself.

MA:

Is this just an elite phenomenon, or is it trickling down to everyday runners?

JR:

It's completely for the everyday athlete. Times across sub-elites and amateurs are dropping significantly — yes, shoes are part of that, but a big part is nutrition. It's now front of mind when people sign up for a race, whereas before they'd start thinking about gels at the Expo. It wasn't seen as part of training. Now amateurs see how the elites have used carbohydrates

to deliver performances, and they're applying it. The next stage is everyday runners moving from "I need a good plan for race day" to "I need to train nutritionally to execute that plan." Periodised nutrition during training elevates training itself: quicker sessions, greater volume, better recovery, and a stronger base. That's what we've been doing with the Kenyan teams —  professionalising nutrition. The same template can move down to the general population.

MF:

Is there a pleasure element to carb-based metabolism? Burning carbs is more oxygen-efficient than burning fat — does it also feel better?  

JR:

You literally just answered it. The body naturally prefers carbohydrates at intensities close to anaerobic, because they're more oxygen-efficient. Oxidising one molecule of glucose takes six molecules of oxygen; oxidising one molecule of fat takes 23. The body has to work significantly harder on fat. That's what "hitting the wall" is, around mile 18 — your glycogen stores are running out, the body transitions to fat oxidation, ventilation goes up, you need more oxygen, but you can only deliver so much. The runner maintains the same perceived effort but slows down because the body is working harder to produce the same output. With sufficient carbohydrate and a steady delivery during the race, you maintain blood glucose, preserve glycogen, and, crucially, the brain runs on glucose. Cognitive function stays sharper, you make better decisions, and the experience becomes more enjoyable.      

MF:

 And in training, not just on race day?  

JR:

Same logic. Athletes do a lot of intense training sessions, often in less-than-ideal conditions. Going into a hard session with low glycogen makes it psychologically and physically much harder. With the right intake during key sessions, you stay mentally alert and have the energy to execute.

MF:

Maurten has recently democratised this strategy through a digital tool — the Fuel Planner. It can't match isotope tracing, but it does suggest we're in an era where everyone gets a slice of the optimisation. How does it work?  

JR:

It's been a big project. The Fuel Planner gives athletes a personalised nutritional plan when they don't have a nutritionist or sport science team behind them. We take what we know from the elite world and translate it for any level. Behind the scenes, there's extensive modelling and simulation — hard science from elite athletes, complemented by data from everyday athletes. The user enters their target time, height, weight, and basic biometrics; we map that to performance and physiological attributes and generate a precise recommendation. Same architecture we use with Sabastian, in a user-friendly interface. We were never satisfied with the old static recommendations — "take seven gels in a marathon at these time points." Good for the population, perfect for nobody. The vision: give every individual simple access to a specialised nutritionist and physiologist.

MA:

What's coming next?    

JR:

Many features are in the pipeline. The next big one rolls out in the coming months: gut training — the same system we built with Sabastian, scaled for someone running a 4 or 5-hour marathon. Same logic, calibrated to their needs.   

MF:

You mentioned bicarb earlier. So far, we've spoken about glucose and fructose — is Maurten expanding the molecular toolkit beyond carbohydrates? 

JR:

We're always running internal research. On the carbohydrate side, we have a very effective delivery system — anything that is multi-transportable and can be packaged into a hydrogel works. But we're also developing other compounds. The Bicarb System, used during Breaking2, is a good example. Sabastian used it on Sunday; so do our female athletes. Traditionally, bicarb didn't fit the marathon model — it was designed for middle-distance athletes working anaerobically. But at 2:50 per kilometre, there's still an anaerobic component, however small. The Bicarb System unlocks those micro gains. Other compounds are in development.

MF:

And on the carbs themselves — is there still ceiling left to push? 115 g/h on Sunday is already remarkable.

JR:

There's potentially room to go higher — data from Ironman athletes and cyclists suggests a higher ceiling. But we're careful how we communicate this. Sabastian's intake doesn't mean someone running a 3 or 4-hour marathon needs the same. That's why we built the Fuel Planner: each person gets the right intake for them. Sometimes more isn't better. Sabastian's numbers are freakish; they're not a template for everyone.   

MF:

Have you spoken with Sabastian recently? How is he doing?  

JR:

We had breakfast the next morning. He's a chill guy — nothing really fazes him, which matters now: overnight, he's gone from a small niche to an international superstar. He'll take it in stride. He felt great after the race, super happy with what he'd achieved. But talk to him, and you realise — he knows he wants more, he knows he can run quicker. The crazy part of this project is that we did all this science to convince ourselves he could break the sub-2 barrier. But we never had to show him the data. He already knew. He knew that time was within him. The whole support team — coaches, scientists — has been learning from him along the way. He's been teaching us.  

MF:

There's a fairy-tale element to Sabastian's trajectory into running history. He has remarkable origins — born in a house without electricity, I read. That self-knowledge before fame is a hallmark of great people throughout history: they always knew where they were going, however far they had to travel to get there.   

JR:

Exactly. What's been most striking is realising that the science, the physiological exploration — all of that has been our journey of discovery, not his. He just went and did his own thing. My role in the end was relatively small to the scale of what Claudio and everyone at the camp contributed. Although we do the science, Claudio, Sabastian, and the team did all the hard work of applying it.

 As such an extreme outlier, Sabastian forces us — and academic physiology in general — to re-establish what we think we know. As a scientist, it's been a once-in-a-lifetime opportunity to observe such a unique body machine up close.