Running a marathon

This Sunday, she participated for the first time in the New York City Marathon. An experience that serves as a starting point to discuss the science behind the 42.195 km. A physical milestone—and an emotional one, at least in New York, where it has been dubbed "the best day of the year" in the city—that also offers a scientific window to better understand the physiology and limits of the human body.

Some general statistics about the marathon: more than 90% of marathon participants reach the finish line; the average finishing time is 4 hours 21 minutes for men and 4 hours 48 minutes for women—with the fastest times belonging to Kenyan Kelvin Kiptum (Chicago 2023; 2:00:35) and Ruth Chepngetich (Chicago 2024; 2:09:56); And, despite its growing popularity, only 0.17% of the world's population participates in a marathon each year. Now, let's get to the science.

A recent study published in Nature Metabolism It has been shown that, after running a marathon, the myelin content is temporarily reduced in specific areas of the brain related to motor, sensory, and emotional coordination. Fortunately, this alteration recovers spontaneously within two months (lucky us!), but it demonstrates how extreme physical activity can directly affect neurological structures.

If we talk about extreme physical activity, Kilian Jornet surely comes to mind, who a few days ago completed the ascent of all 72 peaks over 4,000 meters in the United States in just thirty-one days, a project he called States of ElevationBut, despite achieving extraordinary goals, even (surely) Jornet operates within the limits imposed by physiology.

Science has revealed—with varying degrees of accuracy—the limits of physiological endurance. According to recent researchHumans cannot sustain an energy expenditure greater than 2.5 times their basal metabolic rate, the minimum amount of energy the body needs to maintain its vital functions at rest. In fact, this metabolic ceiling has been observed in both marathon runners and ultra-endurance athletes. Population and individual differences must also be considered. Studies suggest that Women may have specific advantages In long-distance races: a better capacity to metabolize fats, a more consistent pace, and greater resilience to exhaustion.

Nutrition is also a fundamental piece. Both pre-race strategies—for example, carbohydrate loading before exercise—and intake during the race are crucial to avoid sudden exhaustion, known as "hitting the wall." Research shows that many runners do not adequately meet their energy and hydration needs, which limits their performance and increases the risk of injury.

As I was saying, the New York City Marathon is a special and emotional day in the city. There's a festive and celebratory atmosphere. A sense of community and camaraderie among the runners who, spurred on by the crowds cheering them on from the sidewalks, give their all in the 42 kilometers (and then some) that take them from Staten Island, through Brooklyn, Queens, Manhattan, and the Bronx, back to Manhattan, and finally to Central Park.