The Science of Endurance: How Nutrition is Revolutionizing Marathon Running
When Kenyan runner Sebastian Sawe crossed the finish line of the 2026 London Marathon in 1 hour, 59 minutes, and 30 seconds, the world celebrated a historic achievement. However, behind this record-breaking performance lies a transformative shift in sports nutrition that is redefining the limits of human endurance. Modern marathoners are consuming unprecedented amounts of carbohydrates during races, with elite athletes surpassing 90 grams per hour—a practice that has evolved from a controversial experiment to a scientifically backed strategy.
The Evolution of Sports Nutrition
For decades, the focus of endurance training centered on cardiovascular and muscular development. However, recent advancements have shifted the paradigm to include the gut as a critical component of performance. “We’ve moved from a ‘more is better’ mindset to a nuanced understanding of how the body adapts biologically,” explains Reyes Ródenas, a pharmacist and nutritionist at Nutripure. “A marathon isn’t just run with your legs—it’s a full-body metabolic process.”
Studies published in the Journal of Applied Physiology (2025) confirm that the human body can absorb up to 1.2 grams of carbohydrates per minute during prolonged exercise, provided they are formulated with a mix of glucose and fructose. This combination leverages different intestinal transporters, maximizing absorption and delaying fatigue. “The difference between 2.5 hours of running and 2.5 hours of running with optimal fueling is measurable in seconds,” says Ródenas. “It’s about sustaining energy and preventing the ‘wall’—when glycogen stores collapse.”
Training the Gut: A New Frontier
Elite athletes now spend months training their digestive systems to tolerate high-carb intake during races. This includes experimenting with gels, isotonic drinks, and supplements to identify the most effective combinations. “The gut is like a muscle—it needs to be conditioned,” Ródenas notes. “If you don’t train it, you risk gastrointestinal distress, which can