Competitors take part in the Stage 1 of the 36th edition of the Marathon des Sables between Timgaline and Ouest Aguenoun n'Oumerhiout in the Moroccan Sahara desert, on March 27, 2022. A new study looking at ultramarathon runners sheds light on the relationship between running and the brain, from an evolutionary standpoint.JEAN-PHILIPPE KSIAZEK/Getty Images
The brains of ultramarathon runners are of particular interest to researchers because they offer a glimpse into our evolutionary past when humans had to cover long distances to find food and other resources.
A new study by University of Western Ontario anthropologist Jay Stock and colleagues found that long-distance running alters brain function in ways that would have helped early humans forage for their survival.
The study, published last month in the American Journal of Biological Anthropology, looked at how reaction time, episodic memory – the ability to recall information about specific events – and spatial working memory got better or worse among 48 male and female athletes who participated in the 2018 Jordan Ultra and the 2019 Sri Lanka Ultra, two races organized by Ultra X, both of which required runners to cover 250 kilometres over five days.
“You might imagine that your brain is just sort of flatlining when you’ve finished an event like that,” Prof. Stock said.
Researchers found that, compared to baseline tests conducted prior to the races, runners’ psychomotor speed, or reaction time, remained unchanged after reaching the finish line.
The study also found that episodic memory performance decreased by an average of 18 per cent in males and 7.5 per cent in females.
But contrary to the assumption that a person’s brain would be flatlining, the study found that performance in spatial working memory – the ability to store location information and better navigate landscapes – increased significantly.
In males, spatial working memory increased by 12 per cent, while for women the boost was even higher – 46 per cent.
“The only thing that’s pretty much on somebody’s mind when they finish a race like that is replenishing resources, and spatial working memory is essential for foraging and finding food and knowing where to get resources,” Prof. Stock said.
“It kind of fits what you might imagine from evolutionary theory as well,” he added. “We’re a species of ultra-endurance athletes, essentially.”
The study confirms researchers’ hypothesis that when under exertion the body makes decisions about energy trade-offs, sacrificing proficiency in some things, such as episodic memory, and directing scarce energy to fuel more pressing matters such as spatial working memory – the ability to store location information and better navigate landscapes.JEAN-PHILIPPE KSIAZEK/Getty Images
Interestingly, while changes in performance of both kinds of memory were seen in both races, the significant results were found following the Jordan race, where runners lost an average of two kilograms. Runners in the Sri Lanka race “finished, essentially, with the same body mass as they started,” Prof. Stock said.
The finding confirms researchers’ hypothesis that when under exertion the body makes decisions about energy trade-offs, sacrificing proficiency in some things, such as episodic memory, and instead directing scarce energy to fuel more pressing matters such as spatial working memory, he said.
Overall, the study sheds light on the relationship between running and the brain from an evolutionary standpoint, said David Raichlen, head of the Evolutionary Biology of Physical Activity Lab at the University of Southern California, who was not involved in the study.
“A hunting and gathering lifestyle, which is what we’ve engaged in for the last two million years, has a real need for high performance and spatial navigation and spatial memory,” he said.
In further research, Dr. Raichlen said he would like to see a more rigorous methodology to test the study’s findings.
“The next steps would be to do a randomized trial where you were able to isolate the impact of the actual endurance event on memory in a more controlled way,” he said.
The effect of running on the brain has become a fertile field of inquiry, especially over the past decade, in large part owing to advancements in brain imaging technology.
In a study published in May in the journal eNuero, researchers from Florida Atlantic University and Mexico’s National Polytechnic Institute found that running helps maintain memory and fight cognitive decline.
In 2020, researchers from the University of Calgary published the findings of a 10-year study that concluded increased blood flow to the brain explains why people who exercise regularly typically do better on cognitive tests compared to people who are sedentary.
Prof. Stock said his team’s study is the first of its kind to show a link between long-distance running and improved spatial memory.