Running is one of the most popular (and beneficial) ways to get your cardiovascular exercise: It strengthens your heart and bones, improves your mood, and even boosts your confidence. But while the benefits are well-known, some other aspects are a bit more hazy—like whether running outside is just as effective as running on a treadmill, or vice-versa.
Ultimately, “the miles are miles, and running is running,” Amanda Katz, CPT, a certified running coach and host of The Running Explained Podcast told Health.
A persistent myth in the running community is that running on a treadmill is easier—you’re on a moving belt, you can keep the surface completely flat, and you don’t need to worry about air resistance. In fact, a longstanding belief is that you would need to bump up the incline on a treadmill to 1.0% to mimic more difficult conditions outside.
But that’s not the case for the vast majority of runners. According to a 2019 meta-analysis published in Sports Medicine, runners would need to be hitting roughly 6- to 7-minute miles or faster for that incline adjustment to be necessary.
In reality, running on a treadmill can often feel harder than running outdoors for a number of reasons. For one, when you run outside, your body can slightly speed up or slow down, often without you even realizing it. That means you’re not holding the same exact pace throughout your entire run, which can be fatiguing.
“There’s more fluidity in your movement patterns when you are running outdoors,” said Katz. “You can kind of run more by effort.”
Then there’s the mental part: Staying in one spot, without the change in scenery or conditions, can be a mind slog. “To run on a treadmill requires a different level of mental toughness,” said Katz.
Whether you’ve got your eye on a 5K or an ultramarathon, outdoor running and treadmill running can prepare your body to take it on. “Both can get you to the same goal,” Katz said.
The most important part in reaching that goal, though, is putting in consistent training. So that means whichever type of running will help you do that might be the better choice for you.
You may benefit most from running on a treadmill if:
- You run when it’s dark outside: If your schedule only allows for pre-dawn or post-sunset runs, sticking to running inside on a treadmill may be safer.
- You’re experiencing hazardous weather conditions: If snow, sleet, or ice (or dangerously hot or humid temperatures) would make you cancel your outdoor run, having an indoor option can help you work out as planned.
- You’re a caregiver: Having a treadmill in your home (or access to a gym with childcare options) can allow you to stay close by while training.
- You’re training for a specific terrain: If you’re preparing for a race in an area that’s different from what you’re used to (say, training for the hilly Boston Marathon when you live in the Midwest), the incline feature on treadmills can help you get used to that effort.
- You’re a fan of speed training: According to Katz, treadmills are great tools for experimenting with paces and seeing what certain efforts feel like in your body. (However, access to an outdoor track or flat stretch of road would work here, too).
Similarly, you might choose to run outside if:
- You need to train in certain weather conditions: Treadmills are usually indoors in climate-controlled environments, but training outside (in heat and humidity or cold and wind) can help your body acclimate to race-day conditions.
- You’re looking for mental health benefits: Compared with exercising indoors, physical activity outside was linked to greater feelings of revitalization, more energy and engagement, and less tension, anger, and feelings of depression, according to a review published in Environmental Science & Technology.
All in all, when looking at which modality is more effective, you have to take your circumstances into account. “Neither is better,” said Katz. “It’s whatever you need to do to accomplish the training you need.”
If you’re new to running—whether outdoors or on the treadmill—a gradual start can help your body acclimate to the high impact of running, so your muscles, ligaments, and tendons don’t become overstrained by too much too soon.
Beginning with a walk-run is a great intro, said Katz. By interspersing periods of running with walking—say, a 30-second walk and 30-second run—you can get used to what the higher effort feels like without becoming gassed. “Walking allows folks to go further and they can recover better,” Katz said.
Shoot for two or three sessions a week at first; each should be about 20 to 30 minutes. Slot in at least one rest day between each of those efforts, according to Katz. “I think that would be a really great place to start,” she said.
