Is Running Outside Really Better Than Miles on the Treadmill?

Running on the spot has never been so productive.

It’s lower-impact

Runners tend to have shorter stride lengths and higher stride rates on a treadmill than when they’re running outside. According to a 2014 review, that can translate to less impact on weight-bearing joints like the ankles, knees, and hips.

But that review was conducted several years ago. Now, slat-belt treadmills (like Woodway machines and the new Peloton Tread) are on the scene, and they provide even more cushioning.

And get ready to put the whole “running is bad for your knees” argument to rest.

Authors of a 2017 study analyzed the exercise habits of more than 2,500 people throughout their lifetimes and found that those who ran regularly were less likely than nonrunners to report frequent knee pain or have symptoms of osteoarthritis.

You’ll probably burn more calories

A bunch of factors determine whether you’ll burn more calories on a treadmill or outside. For starters, the calorie burn depends on the type and duration of the run.

But on average, it’s likely you’ll torch more calories on the tread, says David Siik, program and content director of Precision Run at Equinox.

“Because many people are now interval training on a treadmill, there’s a much higher level of focus and workload, and they are seeing a much bigger calorie burn,” he says.

That said, if a high calorie burn is your main goal, don’t sleep on outdoor runs. Wind and resistance can force you to work harder, and your body burns extra calories to regulate body temperature when you’re out in hot or cold weather.

“Outdoor running also forces your legs to create turnover and use the ground as resistance, which is harder than tackling miles on a moving belt,” Kennedy says. The trick is to make sure these variables don’t impact your pace. “If you slow down because of them, then the tread wins.”

It’s efficient and effective

If you don’t have a ton of time to sweat, the treadmill wins. Not only is it easy (simply hop on and press start), but it’s also completely under your control.

Plus, you don’t have to think about all the variables outdoor running can present, like getting stuck at crosswalk after crosswalk or stopping to coo at a cute pupper (it happens).

There’s zero concern about weather

Weather is something you always have to think about and prepare for before hitting the trails, road, or track.

“In the summer, you need to run outdoors when it’s not as hot and the sun isn’t directly overhead. And in the winter, it’s best to get out there when the sun is out,” Kennedy says. All of that goes away on the treadmill — hello, flexibility!

By the way, if it is crappy outside, you don’t become more badass by forcing yourself to stay out there. (But it is completely safe to run outdoors in the cold, unless it’s super icy.)

Yes, it’s important to run in potential race-day conditions if you’re training, but Kennedy says quality workouts should be done on good weather days. “There’s always good weather indoors!” she says.

There’s less risk of injury

Yes, you could fly off the back of the treadmill (YouTube stardom will no doubt await), but that’s why the little red safety clip is there (yep, you really should use it).

And, well, no such clip exists (either the safety clip or the YouTube clip) when you run outdoors, where the odds of getting hurt go up, says Siik. “Outdoors running poses the risk of getting hit by a car, rolling an ankle on uneven ground, even causing sun damage (people often forget this can be an issue),” he explains.

Or accidentally seeing a cute pupper, getting distracted, and running into the ocean. Look, it happens, OK?

Something else to consider is how safe you feel while running alone. “If you need to do your workouts before the sun comes up or after it sets and you don’t feel comfortable running outside, the tread is the best pivot,” notes Kennedy.

There’s easy access to help

If you run at a gym, there are trainers, first aid kits, and staff members on hand in case something goes awry.

Plus, there’s quick access to water (that you don’t have to carry), which isn’t always feasible for outdoor runners.

Feel the wind in your hair and the burn in your thighs.

You can still go low impact

Yes, treadmills have less impact than most surfaces found outdoors, but that doesn’t mean you can’t have a low impact run outside.

Light-colored concrete is the hardest to run on, Siik says, so avoid that whenever possible.

“If you can, opt for a dirt trail, short grass, the beach, or your local high school track to reduce impact,” he explains. “Even blacktop is softer than sidewalk concrete, especially when the sun warms the tars and oils and creates a softer surface.”

It can support better bone growth

The softer surface of a treadmill produces less impact on bones and connective tissue, but that also means you won’t stimulate quite as much bone growth.

Over time, a lack of bone growth could result in injury due to bone loss, which is what happens when old bone breaks down faster than new bone is made.

That said, running on a treadmill doesn’t mean all these things are going to happen. A 2019 study found that long-distance runners showed increased levels of bone formation markers without signs of harmful effects on bone growth.

However, the outdoors may have a slight edge in this category, thanks to harder surfaces. Impactful or what?

Your butt can get stronger

Siik suggests that unless you’re on a self-powered treadmill, you’re probably not engaging your hamstring muscles as much on a treadmill as you would outdoors.

That’s because the belt is already moving underneath you, and every time your foot lands in front of you, the treadmill belt brings it back — an action that your hammies and glutes usually oversee.

When you’re outside, those muscles don’t get a break, meaning you’ll build that booty faster.

…as will your lateral movement

Runners are notorious for having weak lateral muscles because running predominantly requires you to move in one direction — forward.

That’s even more prevalent in treadmill-only runners, since there’s never any change in direction. But if you head outside, Siik says, you’ll naturally work in sideways movement when you turn and move around unexpected objects.

Another benefit: Lateral movement improves coordination and helps build stability around your ankles and feet, Siik adds.

You’ll reap more mental benefits

You can’t breathe fresh air, feel a gentle breeze blow through your hair, or bask in the sun warming your skin when you run on the treadmill. Being in nature can contribute to a better state of mind.

A 2011 review of studies found that when people hit the open road, they experience a greater energy boost along with a drop in tension, anger, and depression as compared to an indoor run.

You learn to adapt

“Outdoor running conditions the body to make unexpected physical changes, like stepping over a curb, turning a hard left, or maneuvering around people,” Siik says. “These things are important to keep a strong and stable body.”

Kennedy says that if you’re training for a race, outdoor running also prepares you (both mentally and physically) for elements that are out of your control.

Constantly changing terrain and weather can have a big impact on your mental game come race day, but if you prepare for them with outdoor training runs, they’re less likely to throw you off when it counts.

There’s no clear winner in the debate between running outside and hitting the treadmill. It all depends on your fitness goals, preferences, and lifestyle. And you’ll get the biggest boost from doing a mix of both.

Just make sure you lean on a form of running you enjoy. You’ll get the most from your running lifestyle when you keep it consistent.

Samantha Lefave is a freelance writer who is living, eating, and sweating her way around the world. You can find her Instagramming her favorite destinations, squeezing a “Friends” quote into every conversation she can, or — when there’s downtime — eating peanut butter straight from the jar.