How fast is the backyard ultra craze growing, you ask? Last month, Dan England wrote a great feature for RUN detailing the rise of the quirky race format, which was introduced by Barkley Marathons founder Gary Cantrell in 2012 and involves completing one 4.167-mile loop every hour on the hour (adding up to 100 miles per 24 hours) until you give up. At the time, the world record was Harvey Lewis’s 108-lap performance, which works out to 450 miles in four and half days.
Now, just a few weeks later, Lewis is down to fourth in the rankings after three Belgians notched 110 laps to win the Backyard Ultra World Team Championships, which featured teams from 61 countries. Cantrell estimates that at least 25,000 people have run official backyard ultras this year alone. What started out as a novelty race is now a surprisingly popular way of testing your limits—which makes the format intriguing to scientists seeking to understand what defines those limits.
Sure enough, the first study of backyard ultra racers was recently published in the European Journal of Applied Physiology. It’s from a team of Belgian…
