The news desk
On October 1, 2026, Runner's World reported on a small study published in PLOS One comparing differences in energy expenditure between outdoor running and treadmill running. The study included 12 highly trained male runners who ran 5 days per week with a weekly mileage of about 40 to 50 miles, and the results showed that these runners had higher energy expenditure and oxygen consumption when running on an outdoor track than on a treadmill at a 1% incline, with worse running economy, and the difference was most pronounced near the second ventilatory threshold (around 7:10 to 7:22 pace). Currently, there is only this one report on the event, and no follow-up studies or differing conclusions have emerged.
A small PLOS One study found that 12 highly trained male runners who ran at least five days a week, averaging about 40 to 50 miles, had higher energy and oxygen costs and worse running economy outdoors than on a 1 percent incline treadmill, with differences most apparent near the second ventilatory threshold (about a 7:10 to 7:22 pace).