Bundle up, Runners: A Peloton Coach Says You Should Log Miles Outside *At Least* Once a Week

"It's so different running outside and inside," Gentry explains. While neither one trumps the other, in her opinion, braving the elements on a regular basis will provide an extra challenge for your bod. "Subtract one of those [treadmill workouts] and take a 45-minute outdoor session. Just take it outside so you can run with the wind, and rain, and outdoor resistance," she says.

Jenny Hadfield, a coach and author of Marathoning for Mortals, told Runner's World that pushing against a headwind will make you work way harder. Yes, that may mean your pace will go down, but the level of effort you're exerting throughout the run will increase—kinda like when you put the incline up on the tread.

The more extreme outdoor temperature also puts an added strain on your body, says David Siik, creator of Equinox's Precision Running program. That said, he notes that cold-air quality is actually worse than warmer air, so try to plan your outdoor winter runs for the warmest day of the week.

Yes, it will take some major willpower to battle it out with Jack Frost. But according to the experts, you'll be better for running outside come spring—and so will your PR.

If you're wondering how long your runs should actually be, here's your answer. Plus, why logging your miles helps build muscle.