America's greatest fitness success story

You may be surprised to learn that the treadmill was invented as a prison torture device in 19th-century England. Or maybe you're not surprised, depending on your feelings about huffing and puffing as you trod along on an automatic belt to nowhere. Still, it's a little wild to realize that upward of 50 million Americans willingly use a device each year that was conceptualized to make criminals suffer. A lot of people are gluttons for punishment, though.

Exercise fads constantly come and go. In 2025, that means spin classes are out, Pilates and strength training are in, and the Thighmaster is probably sitting somewhere in your great aunt's basement. Americans tend to treat fitness as a consumer product to be used and, once we get bored or something better comes along, tossed aside. Yes, exercise science evolves, and doctors' recommendations on the best ways to stay fit change over time, but not nearly as fast as whatever Hot New Thing the cool kids are into cycles through.

If there is an exception to the fadification of fitness, it is the humble treadmill. Both literally and figuratively, it doesn't go anywhere.

Data from the Sports & Fitness Industry Association, a trade association for the sporting goods industry, shows 56.8 million Americans used a treadmill in 2024. That is a … 0% change from 2019. People use the treadmill at about the same rates as they jog or lift free weights. The only sporting activity that's more popular is walking.

"We've been tracking participation trends for 38 years, and in the current iteration, we've been tracking it since 2008, and treadmill has always been one of the most participated sports," says Alex Kerman, the senior director of business operations and research at SFIA.

According to SFIA's research, 18.4% of the US population ages 6 and up use a treadmill at least once a year, a small uptick from 17.2% in 2014. Treadmill use cuts across ages, demographics, geographies, and income levels, though it tends to skew female, higher-income, college-educated, and white. Given their mainstay status, it's perhaps not a surprise that treadmills are the most lucrative piece of gym and exercise equipment in the US, generating about $1.1 billion in revenue in 2025, according to data from IBISWorld.

"The treadmill endures because it really delivers on the essential basics: accessibility, convenience, and proven effectiveness," says Cedric Bryant, the president and CEO of the American Council on Exercise. "The most basic element to maintaining an independent lifestyle, typically, as we mature, is to be able to ambulate and move on our own. Treadmills help to maintain that quality."

The treadmill's hold on our society started in the late 1960s and 1970s. Aerobic fitness started to take off as people realized and publicized the cardiovascular benefits of moving and shaking. Jogging took off as an easy, cheap way to get your heart rate up. While plenty of people partake in outdoor running and walking, others prefer to do it inside.

"The treadmill sticks around because running and jogging stick around," says Natalia Mehlman Petrzela, a history professor at The New School who's the author of "Fit Nation: The Gains and Pains of America's Exercise Obsession." "Most people can put one foot in front of the other and walk or jog, and it's that much easier to not have to deal with the elements or the time of day."

Treadmills are versatile — they can be used by beginners starting out walking or more advanced athletes doing interval training and playing around with elevation. A treadmill can be a place to do a little (careful) multitasking. In terms of improving cardiovascular health, increasing endurance, and helping with weight management, it delivers bang for your buck, whether at the gym or in your basement.

"There's millions of people that have health club memberships, and the treadmill is right there, free to use," Kerman says. "They've made models now that are affordable for at-home purchase as well."

Treadmills can deliver the mental health benefits of exercise, be a space for zoning out or getting in a good think, though the endeavor can, admittedly, be pretty boring. Luckily, treadmill technology has improved, so maybe that device that wasn't for you 10 years ago would be now. Many of them have TVs, and some offer interactive classes. A lot of modern-day treadmills also have less of that "might fall off of them with any wrong move" feeling.

"We pay big bucks for fancy connected treadmills," Mehlman Petrzela says. "As we want more out of our workouts, we want more out of less time. Running is both old school and basic, but it's kind of hard to beat that."

Of course, exercise trends have come for the treadmill, too. There's the 12-3-30 "hot girl" workout that's popular among a certain type of, well, hot girl, or the Zone 2 cardio focus. Boutique studios such as Barry's and Orangetheory also incorporate pretty tough treadmill work.

Carmine Ciliento, a fitness manager at Crunch Fitness, tells me he's not always in love with some of the treadmill-based workout trends that come from social media influencers. "If the person looks the part and talks in a convincing way, people will be like, 'All right, let me try that," he says. The 12-3-30, where you walk 3 miles per hour at a 12% incline for 30 minutes, has a "very arbitrary rationale," he says, and while Zone 2, a moderate-intensity workout, has become popular, it's not a "magic pill" either.

But if an influencer or some flash-in-the-pan fad gets people to move, so be it, Bryant says. "That can generate even more interest and excitement around this product that's been around forever," he says. There is research to support the benefits of the 12-3-30.

Ciliento himself got into running in 2019 and mainly uses the treadmill for tempo work, but he understands that running may not be for everyone. It generates a lot of impact, which can be tough on joints and could increase the risk of injury, and many Americans, especially those who didn't play sports growing up, mainly remember dreading that timed mile in high school gym class.

"As much as I've invested my time into running over the last couple of years, I don't tell people they need to run," Ciliento says. "That being said, the more resilient someone becomes physically, emotionally, and mentally, the more you could kind of start to reintroduce things that they might've strayed away from at one point or another."

Fitness crazes tend to grab the headlines and, for some of the fitness fiends out there, their hearts and wallets. Tae Bo, Jazzercise, and hula hooping are just some of the once hot modalities that have fallen by the wayside. It's tempting to laugh at how weird some of them were, but the fact of the matter is, the best exercise is the one you'll keep coming back to. If it takes a Zumba class to get you moving, or if you fall back in love with that Gazelle machine, whatever. The problem is, a lot of these fads are not ones people stick with once the novelty wears off.

The treadmill is, for many people, a consistent friend. It's simple, familiar, and incorporates movements we evolved to do. Sure, it's not the most entertaining piece of exercise equipment in the world. But maybe that's part of its lasting appeal: It wasn't designed to be fun in the first place.

Emily Stewart is a senior correspondent at Business Insider, writing about business and the economy.

Business Insider's Discourse stories provide perspectives on the day's most pressing issues, informed by analysis, reporting, and expertise.