Danielle Friedman
The treadmill doesn’t get a lot of love. But with cold weather forcing people in the northern hemisphere indoors the past few months, it makes sense that one of the most popular workouts on TikTok right now features the machine.
The workout is known as 12-3-30, and the premise is simple: walk at an incline of 12 per cent and a pace of 3 miles per hour (around 4.8 kilometres per hour) for 30 minutes.
A Miami-based fitness influencer first posted about the workout in 2020, and it quickly started trending. In the years since, new waves of devotees have embraced it, and in recent months, it’s seen another uptick in interest.
While the workout’s creator originally promoted it for weight loss, its fans claim it’s an accessible, low-impact way to develop an exercise routine, improve cardiovascular fitness and build strength. People on social media often post about doing it daily, or several times a week, as part of a 30-day fitness challenge.
“The prescriptive nature” of 12-3-30 appeals to people who feel overwhelmed when trying to pick a workout, says Michael Wong, an assistant professor-in-residence of kinesiology at the University of Nevada, Las Vegas, who published a small study on the routine last year. They appreciate feeling like, “‘I know what to do when I go to the gym,’” he says. “‘I just set the treadmill at this, do it for 30 minutes, and then, boom, I’m done.’”
We asked sports medicine and exercise science experts what the workout’s benefits are and what to know before trying it.
Walking at an incline puts good stress on your heart
While going for a brisk walk on any terrain helps condition your cardiovascular system, walking on an incline is more beneficial than a flat surface, since it puts more stress on your heart and lungs, says Dr Eli Friedman, who directs the sports cardiology program at Cedars-Sinai Medical Centre.
The incline serves as a form of resistance, which requires your lower body muscles to work harder to propel your body forward.
This, in turn, elevates your heart rate and pushes your cardiorespiratory system to work harder to deliver oxygen to your muscles. “That’s why we may feel a little bit more short of breath” compared with walking on a flat surface, Friedman says.
Over time, incline walking can help strengthen your heart and improve your VO2 max, or how well your body can deliver oxygen to your muscles, he says.
It can also strengthen your lower body – to a point
Walking at an incline can help strengthen your glutes, hamstrings, quads, calf and ankle muscles, while putting less stress on your joints than higher-impact cardio.
It can also work your core muscles, especially if you make an effort to engage them as you walk, says Dr Carolyn Chudy, the director of physical medicine and rehabilitation at the virtual orthopedic care provider Vori Health.
You won’t build the same muscle as you would from progressive strength training, she says, and eventually, “you’re going to plateau.” Still, you’ll gain more strength from it than walking on flat terrain.
Aim for a variety of workouts
If you’re drawn to the simplicity of the 12-3-30 workout and don’t have any underlying health conditions, you can do it safely several times a week, the experts say. (Doing this workout five times a week would meet The American College of Sports Medicine’s recommendation of 150 minutes of moderate to vigorous aerobic exercise weekly.)
However, your heart and the rest of your muscles benefit from variety. Ideally, your fitness routine “should be ever-changing and adapting,” Friedman says. He recommended alternating the 12-3-30 workout with other forms of cardio and strength training, to keep challenging your body in new ways.
On the flip side, if you mostly walk on flat surfaces, incorporating incline walking into your routine may help to improve your overall fitness and performance.
Ease your way in
Before you dial the treadmill up to an incline of 12, experts suggested warming up on a lower grade, to give your heart and muscles time to acclimate.
You may also need to build up your fitness to tackle 12-3-30, says Hunter Carter, an exercise physiologist at Hospital for Special Surgery in New York. See how the workout feels at different inclines and paces, he said, and strive for a sweet spot of challenging but sustainable.
If you need to hold on to the handrails to support yourself, that’s a sign you should decrease the incline, the speed or both, Carter says. Otherwise, you’re “reducing the amount of work that you are doing and therefore the potential benefits”.
He also recommends leaning forward slightly when walking at a steep incline, both for balance and to generate more force. Pumping your arms can help you engage your core and work your upper body.
Ultimately, you’re most likely to stick with a workout if you enjoy it, Friedman says. If the 12-3-30 approach inspires you to move, you’ll benefit for as long as it’s challenging – and fun.
The New York Times
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