What’s the difference between walking or running outside versus on a treadmill? Is one better than the other?
The short answer is: “it depends.”
Running on a Treadmill
By no means is treadmill running bad for you—especially if the alternative is being sedentary—but there are a couple of cons to keep in mind when running on the treadmill.
Let’s start by talking about treadmill momentum. Anyone who has spent time walking or running outside and on a treadmill will tell you that there’s a difference between the two. One crucial reason why walking or running on a treadmill is easier is because the treadmill belt moves to propel you backward.
The backward movement of the belt creates treadmill momentum and allows you to walk or run on a treadmill even though you’re stationary. You have to take alternating steps forward with your legs to stay on the treadmill.
The problem with the treadmill belt constantly moving backward is that you don’t have to provide as much push-off with your glutes, hamstrings, and calf muscles (the muscles on the back of your hips and legs).
Instead, most of the work comes from your hip flexor and quad muscles (the muscles on the front of your hips and legs). Too much mileage on the treadmill can contribute to muscle imbalances, pain, and injuries.
One way to compensate for treadmill momentum is to add 1% or more incline because it simulates running outside. BUT, just because adding an incline makes walking or running on a treadmill more challenging, it doesn’t make your glutes, hamstrings, and calves work harder because it doesn’t change treadmill momentum. Adding incline continues to make the front of your legs work harder.
Another con of running on a treadmill is that the machines max out incline and speed and cannot simulate downhill running, which is essential if you’re training for a race, and treadmills can be tedious and monotonous.
Runners notoriously deal with impact and overuse injuries. Treadmills absorb ground reaction forces, and running on a cushioned belt is more forgiving than running on a hard surface.
A treadmill is an excellent option if you’re looking to log a few miles to keep up your cardio as part of a well-rounded fitness routine. If you’re a regular outdoor runner, the treadmill is a great option for situations where running outdoors can be impractical or dangerous, like extreme weather and running in the dark. And if you’re training for a race, the treadmill is an excellent tool for the structured speed workouts in your training plan.
The treadmill can also be great for runners returning from injury (and runners who want to prevent injury). If you’re not ready for the ground reaction forces of running on concrete or asphalt, I recommend slowly transitioning into running on a treadmill before running out on the road.
There is a difference between running outside versus on a treadmill. Even though running outside is often more challenging, whether it’s better than on a treadmill depends on the person and these factors:
- The weather – if it’s 10 degrees or 100 degrees outside, using the treadmill would be a good choice.
- Convenience – if you have young children like me, exercising before your kids wake up or while playing or watching tv might be the only option.
- Outdoor environment and safety – a treadmill might also be a good choice if you live in an area with a high crime rate, a lot of smog, or many busy streets you have to cross.
A treadmill belt lacks uneven terrain, so you’re activating more muscle running outside. Your feet have to grab the ground to propel you with every step—think about dodging people on the sidewalk or hopping over curbs. The interesting thing is that the uneven terrain doesn’t need to be extreme to stimulate your muscle fibers to work harder.
The slight unevenness of an asphalt road surface with an occasional pebble is enough to make you notice the difference between running outside versus on a treadmill.
And research repeatedly shows that running outside delivers a bigger energy boost and results in less tension, anger, and depression than running inside.
The Bottom Line
There are pros and cons to running outside and running on a treadmill. A treadmill is an excellent option if you are interested in cardiovascular benefits. But if you’re training for a race, you will benefit more from running outside (for at least part of your training). Figure out which option works best for you and try to do both as much as possible.