Last week, Sabastian Sawe made marathon history by smashing the two-hour barrier in London. The 31-year-old Kenyan completed the 26.2-mile course in just one hour, 59 minutes, and 30 seconds, clocking in a blistering average speed of 13.2 miles per hour (21.2 km/h). While the sporting world is reeling from this momentous achievement, experts caution that Sawe's record might not stand for long.
Scientists say athletes haven't hit the ultimate limit
Scientists say that athletes still haven't reached the ultimate limit for the marathon, and runners could clock faster times before the next Olympics in 2028. In the past, scientists calculated that the absolute fastest time in which a human could physically complete a marathon was one hour, 57 minutes, and 58 seconds. However, massive advancements in strategy, training, nutrition, and shoe technology could see athletes blasting through the human threshold.
Dr. Olivier Roy-Baillargeon, running expert at The Running Clinic, told the Daily Mail: 'Nothing tells us that this theoretical limit is an actual one. Of course, no one will ever run a marathon in 1:30. But could we see a 1:56, or even a 1:55 someday? I wouldn't bet against it.'
Marathon times have been getting faster at a staggering rate
In the last few decades, marathon times have been getting faster at a truly staggering rate. Since Morocco's Khalid Khannouchi set the world record at 2:05:42 in 1999, subsequent athletes have shaved more than five minutes off his time. By 2019, Kenya's Eliud Kipchoge had become the first person to ever run a marathon distance in less than two hours, setting the time outside of competition conditions. Less than a decade later, two athletes – Sabastian Sawe and second-place finisher Yomif Kejelcha – finished in under two hours in race conditions during the London Marathon.
Super shoes: a game-changer in running
Dr. Peter Lamb, a biomechanics expert from the University of Otago, New Zealand, told the Daily Mail: 'Marathon times are getting faster, for a large part because of the carbon-plated super shoes.' So-called 'super shoes' feature an aggressive 'rocker' profile, extremely tall foam cushioning, and stiff carbon-fibre plates. These shoes return more energy from each stride into the runner's step, adding a springy bounce that improves running efficiency. This means runners burn less fuel and less oxygen for every step, enabling them to put more power into propelling themselves forward while keeping their legs fresh.
Studies have shown that super shoes can improve running efficiency by as much as four per cent, with elite runners potentially benefiting even more. Dr. Jean-Francois Esculier, clinical associate professor at the University of British Columbia, told the Daily Mail that super shoes also have a powerful psychological effect. In his research, Dr. Esculier found that runners performed better on race day if they simply believed their shoes were advanced technology. 'Runners could potentially be willing to push more if they believe they have the right tools to do it,' he explains. 'I believe the mental aspect of performance needs to be emphasised. In the world of performance, small details matter.'
After Kipchoge set his sub-two-hour marathon time wearing a pair of prototype Nike Alphafly super shoes, World Athletics has put strict restrictions on shoe design. However, highly efficient super shoes are still race legal, provided they don't have a midsole that exceeds 40 mm in height or contain more than one carbon-fibre plate. The super shoes worn by Sawe during the London Marathon, the ADIZERO Adios Pro Evo 3, weigh less than 100g and pack in 39 mm of specialised high-energy foam for extra bounce.
Nutrition and training: the other pieces of the puzzle
But new shoes are only one piece of the puzzle when it comes to cracking ever faster marathon times. Surprisingly, experts say that the 'biggest breakthrough' for modern athletes has been the astonishing amount of food they manage to eat during the race. David Roche, an ultramarathon runner and running coach, told the Daily Mail: 'What we thought was an endurance limitation was largely a fuelling limitation. Athletes are taking over 100 grams of carbohydrates per hour in hard training and racing, compared to 60 or less in the previous generation.'
In 2025, during the Berlin Marathon, Sawe consumed 105g of carbohydrates per hour throughout the race, bumping this up to 115g for London. This volume of food, which would have seemed absurd to earlier runners, gave Sawe enough energy to push hard, deeper into the race. That improvement comes from a combination of better strategy and better food options like energy-dense gels. 'No one could have taken in these carb levels with the gels of 2010,' explains Mr. Roche.
While Mr. Roche thinks the absolute cap for carb consumption while running is probably between 120 and 150 grams per hour, this still leaves a lot of room for improvement. 'I think we'll see a 1:56 in the next 50 years, and I think that a large portion of that will come from tech advances in fuelling and performance science,' he says.
At the same time, runners are making big changes to their training strategy to help them maintain intense speeds for longer periods of time. Part of what made Sawe's performance in London so impressive was his 'negative split', meaning he ran the second half of the marathon faster than the first. Dr. Roy-Baillargeon explains that, physiologically speaking, modern athletes are right at the very limit of what is humanly possible. The big change has been a massive improvement in durability, technically known as physiological resilience.
'By far the most important difference between the current and previous generation of athletes is the emphasis on astronomical volumes of easy running,' says Dr. Roy-Baillargeon. Methods developed by the world-renowned Italian coach Renato Canova, who trains top athletes Emile Cairess and Amanal Petros, advocate for running massive distances at relatively gentle paces right up to race day. Dr. Roy-Baillargeon says: 'In the specific preparation phase, his marathoners can run 50km in one day, including up to 40km at marathon pace or slightly faster, on hilly courses around 2,200m above sea level. And that's to conclude around 240km running weeks.'
As these methods become more common, an even larger group of runners will be hitting sub-two-hour splits during their race. Professor Grégoire Millet, a marathon expert from the University of Lausanne, predicts that this will lead to even faster times. 'We are getting close to a plateau, but with more runners – a higher density – we expect better drafting effect between them,' he explains.
Professor Millet suggests that marathon running may soon see a 'Roger Bannister effect' – named for the sudden increase in runners setting four-minute miles after Roger Bannister's record run – in which multiple runners break the two-hour barrier in the coming months. If this happens, it might not be long at all before Sawe's record is broken, with Professor Millet predicting a 1:58 marathon before the 2028 Olympics in Los Angeles.
