Human bodies are perfectly adapted for endurance running. How far can we go? (Image credit: Golser via Getty Images)
Many people have trouble running even a mile; others can easily cover 10 km. Some brave souls try their hand at “ultramarathons” – races over 26.2 miles (42.2 km). But how far can a person run before they just have to stop?
To answer that question, we first need to figure out what exactly it means to “stop.” Dean Karnazes holds the unofficial record for the longest run without sleep: 350 miles (563 km), which he completed in three and a half days in 2005. In 2023, ultramarathoner Harvey Lewis set a new record for a long-distance race known as a backyard ultra. In this competition format, competitors run a 4.17-mile (6.7 km) loop every hour until only one runner remains. Lewis completed 108 such loops in as many hours (4.5 days total), covering 450 miles (724 km), with a few minutes of rest at the end of each hour before moving on to the next one.
Because ultrarunners often take short breaks to walk, eat, tie their shoes, use the bathroom, or, depending on the type and length of the race, even sleep, there is no official record for the longest run without stopping. But if there were, the call of nature would likely be the most significant limitation.
“I think the need to urinate will be the limiting factor,” said Jenny Hoffman, a Harvard physicist and ultra-distance runner who holds the world record for the fastest woman to cross America on foot (she achieved the feat in 47 days, 12 hours, and 35 minutes).
Beyond the brief pauses needed for biological needs, humans have a number of characteristics that make them good at endurance running, said Guillaume Millet, an exercise physiologist at Jean Monnet University in Saint-Etienne, France. Humans have relatively large gluteal muscles that help with forward propulsion, the ability to store elastic energy in tendons and muscles, and strong neck ligaments that keep the brain stable while running.
Humans are also well-adapted to running in the heat because we can regulate our body temperature through sweating. “Even in fairly hot external temperatures, we’re able to keep our core temperature fairly low, which is a significant advantage compared to most other species,” Millet told Live Science.
Despite these adaptations, humans never evolved specifically to run such extreme distances. “For most of our existence, until recently, humans had to work very hard to survive,” Lieberman said. “If you run correctly, avoid injury, and watch your nutrition, it’s amazing what the body can do, but that’s not what we evolved for. It’s maximizing normal adaptations to the limit.”
A number of physical factors, such as injuries, muscle fatigue, or lack of sleep, can cause a runner to stop and recover. However, mental toughness is also important in endurance running. Ultramarathoners must be able to push through pain and exhaustion to keep going for days on end.
“We have evolved an extraordinary ability to push ourselves to perform a variety of exceptional tasks. It has to be a desire,” said Daniel Lieberman, an evolutionary biologist at Harvard University. “So I think the most important limiting factor in human endurance is psychology.”
Those who truly push themselves to such extremes require extensive training to avoid injury. Before her transcontinental run, Hoffman trained to run 200 miles (322 km) a week to build both the aerobic endurance for long workouts and the bone strength to withstand repeated impacts from the pavement.
Sourse: www.livescience.com
