Running Outside vs. On a Treadmill: Which Is More Effective?

Running is one of the most popular (and beneficial) ways to get cardiovascular exercise: it strengthens your heart and bones, improves your mood, and even boosts your self-confidence. But while the benefits are well known, other aspects are a little more unclear, such as whether running outside is as effective as running on a treadmill, or vice versa.

Ultimately, “miles are miles, and running is running,” said Amanda Katz, CPT, certified running coach and host of The Podcast Explained Running said 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 have to worry about air resistance. In fact, it has long been believed that you should increase a treadmill’s incline by up to 1.0% to mimic harsher conditions outdoors.

But this is not the case for the vast majority of runners. According to a 2019 meta-analysis published in Sports medicinerunners would need to complete miles around 6-7 minutes or faster for this incline adjustment to be necessary.

In reality, running on a treadmill can often seem more difficult than running outside for several reasons. For one, when you run outside, your body may speed up or slow down slightly, often without you even realizing it. This means you don’t maintain exactly the same pace throughout your run, which can be tiring.

“There’s more fluidity to your movements when you run outside,” Katz said. “You can kind of run more with the effort.”

Then there’s the mental part: staying in one place, with no change in scenery or conditions, can be a real headache. “Running on a treadmill requires a different level of mental toughness,” Katz said.

Whether you have a 5K or ultramarathon in mind, outdoor running and treadmill running can prepare your body for it. “Both can get you to the same goal,” Katz said.

However, the most important part of achieving this goal is consistent training. So this means that whatever type of running will help you do this could be the best choice for you.

You may benefit more from running on a treadmill if:

• You run when it’s dark outside: If your schedule only allows you to run before dawn or after sunset, it may be safer to run indoors on a treadmill.
• You are experiencing dangerous weather conditions: If snow, sleet or ice (or dangerously hot or humid temperatures) force you to cancel your outdoor run, having an indoor option can help you train as planned.
• You are helping: Having a treadmill in your home (or access to a gym with childcare options) can keep you nearby during your workout.
• You are training for a specific terrain: If you’re preparing for a race in a different area than you’re used to (for example, 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 are a fan of speed training: According to Katz, treadmills are great tools for experimenting with cadences and seeing how certain efforts feel in your body. (However, access to an outdoor trail or flat stretch of road would work here too).

Likewise, you can choose to run outside if:

• You need to train in certain weather conditions: Treadmills are typically set up indoors in air-conditioned environments, but training outside (in the heat and humidity or in the cold and wind) can help your body acclimate to race day conditions.
• Looking for mental health benefits: Compared to indoor exercise, outdoor physical activity was linked to greater feelings of revitalization, more energy and engagement, and less tension, anger and feelings of depression, according to a study published in Environmental science and technology.

Overall, when researching which modality is most effective, you need to consider your situation. “Neither one is better,” Katz said. “That’s all you need to do to accomplish the training you need.”

If you’re new to running, whether outdoors or on a treadmill, starting gradually can help your body acclimate to the high impact of running, so your muscles, ligaments, and tendons aren’t overworked too soon.

Starting with a walk-run is a great introduction, Katz said. By interspersing periods of running and walking (say 30 seconds of walking and 30 seconds of running), you can get used to the feeling of higher effort without feeling gassed. “Walking allows people to go further and recover better,” Katz said.

Photograph two or three sessions per week at first; each should last about 20 to 30 minutes. Allow at least one day of rest between each of these efforts, according to Katz. “I think that would be a really good place to start,” she said.