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There are, however, benefits to running on the treadmill, running coaches and exercise scientists say. The record-breaking temperatures and the poor air quality from the Canadian wildfires this year have made running outside risky or outright dangerous at times. Treadmills allow runners to keep training despite inclement or hot weather.
“Treadmills are misunderstood by a vast majority of the people,” said James McKirdy, a running coach. “Having that option is important and can be pivotal in the success of someone’s goals.”
We asked running experts about the effectiveness of treadmill running and how to get the most out of those workouts.
Is running on the treadmill as effective as running outside?
There are subtle differences with running on the treadmill, but it is largely as effective as training outside, experts say.
While energy consumption is “very, very slightly lower,” in treadmill running, the differences are minor, said Bas Van Hooren, a competitive runner and researcher at Maastricht University in the Netherlands. At speeds of up to 16 kilometers per hour, which is roughly a six-minute per mile pace, treadmill running results in similar oxygen costs and heart rate compared to outside running, he said.
The slight difference in energy consumption, though, can add up if you do the majority or all of your training on a treadmill, Van Hooren added.
The treadmills themselves may also have limitations. Some can only go up to a certain speed, and others, whether because of quality or wear and tear, can display inaccurate paces on the screen, McKirdy said.
Do I have to use the incline?
Some runners put treadmills at a 1 percent incline in an effort to match the energy costs of running outdoors, but that isn’t necessary, said Van Hooren, who has been a co-author on reviews on treadmill running. Keeping your treadmill at a zero percent incline is fine.
Increasing the incline on treadmills can be useful, though, for hill repeats or to mix up your workouts.
“Hill workouts might be easier on treadmills, because if you’re doing it outside, it might take a long time to get down the hill,” said Olympian Kim Conley, a running coach. “But on a treadmill, you can go as long as you want or short as you want on your recovery.”
How does the treadmill affect my running form?
Experts recommend taking at least a few minutes to familiarize yourself with running on a treadmill.
Unlike outdoor runs where you’re propelling yourself off the ground, the belt is moving under you on a treadmill, said Andrew Schille, a clinical research coordinator at the Emory University Sports Performance and Research Center.
People who are not accustomed to treadmill running may adopt a slightly higher step frequency and land a bit more toward the front of their foot compared with the heel of their foot, Van Hooren said.
The stiffness of the treadmill makes a difference. It may affect how you run and even your foot strike, Van Hooren said. The stiffer and less springy treadmills are more comparable to running outside on pavement.
To measure the stiffness of a treadmill, bounce a ball on the concrete and measure the bounce height with a camera — try the slow motion mode on your phone, Van Hooren recommends. Then bounce the ball on a treadmill and compare the height.
You can also base it on how much you feel you’re sinking into the treadmill, said Sarah Dillon, an assistant professor in physiotherapy at the University of Limerick’s School of Allied Health.
On a very stiff treadmill, runners typically will adopt more of a heel strike, which may take a bit more load off the Achilles’ tendon but increase the load on the knee, Van Hooren said. Conversely, on a bouncier treadmill, runners will use more of a forefoot strike, which puts more load on the Achilles’ tendon but less load on the knee, he said.
The science suggests, however, that it doesn’t matter if you’re adopting a forefoot or heel strike, Van Hooren said. “At least for energetics, you’re using the same energy cost, regardless of whether you are adopting a heel strike or forefoot strike,” he said.
Why does treadmill running feel harder than running outside?
The physiological demands of running on the treadmill and outside are similar, but the perceived effort of treadmill running can be higher, experts say.
In a 2019 review, Van Hooren and his co-authors speculated on the reasons runners prefer outdoor running.
It could be partly because runners have greater control over their speed and the ability to stop moving, they wrote. They also have a lower risk of falling than on the treadmill. It might also be because, the authors wrote, our body temperature during treadmill running increases because of less air flow.
What types of workouts should I do on the treadmill?
Conley, who has an online coaching service and competes at an elite level, recommends workouts that may be easier on a treadmill, such as speed or hill workouts.
Kelly Walsh, a 37-year-old marathoner and ultramarathoner based in Nashville who is coached by Conley, got into treadmill running during the pandemic. When her area gym shut down, Walsh bought a treadmill and would use it when it got cold outside.
Treadmill running allows her to take the mental strain out of speed work or hill repeat sessions, she said. The treadmill, with its set speed, also prevents her from running too fast on easy runs, said Walsh, who has a personal best of 3 hours 56 minutes 3 seconds in the marathon.
Here is one workout Conley suggested to Walsh:
- 15-minute warm-up at 6 mph (10 minutes per mile)
- 10 repetitions of 90 seconds at 7 mph (8:34 per mile pace) with a 4 percent incline, followed by 90 seconds at 6.3 mph (9:31 per mile pace) with no incline
- 15-minute cooldown at 6 mph
How can I make treadmill running less boring?
Focusing on something else can help make treadmill running more enjoyable.
Put a shirt or towel over the clock on the treadmill. Watch a movie or TV show. Take a virtual class. Listen to a podcast or music that matches the tempo that you’re running.
You can also use treadmill runs as a way to test different types of fuel without worrying about being outside and not having access to a restroom. Walsh experiments with different gels and breakfast before running on the treadmill “just to make sure it sat well with my stomach,” she said.
Just remember, treadmill running counts as part of your training. “Miles are miles, and we all have to do our best to get them in when we can,” Walsh said.
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