Fitness experts dissect the viral fitness trend.

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The treadmill—or as many people call it, the dreadmill—doesn't typically get a lot of love. But thanks to a recent viral TikTok trend, this fitness tool is receiving tons of hype.

The trend, known as the "12-3-30" workout, is soothingly straightforward: You set your treadmill to an incline of 12 and a speed of 3 miles per hour and then walk for 30 minutes. The concept originated from social media influencer Lauren Giraldo, who shared it on YouTube in 2019 and again on TikTok in November 2020, where a video explaining the workout racked up nearly 12 million views and more than 2.7 million likes (and counting).

"I used to be so intimidated by the gym and it wasn't motivating," Giraldo explained in the 37-second TikTok video. "But now I go, I do this one thing, and I can feel good about myself." The 12-3-30 workout, Giraldo said, helped her lose 30 pounds.

As for the origin of this routine? "I'm not a runner, and running on the treadmill was not working for me," Giraldo told TODAY.com. "I started playing around with the settings, and at the time, my gym's treadmill had 12 incline as the max. The three miles per hour felt right, like walking, and my grandma had always told me that 30 minutes of exercise a day was all you needed. That's how the combination started."

Giraldo isn't the only one who swears by this routine. Search "12-3-30 workout" on YouTube, and you'll see tons of rave reviews praising it as a great way to lose weight, boost fitness, and feel excited about exercise. But is 12-3-30 really worth the hype? We asked three fitness experts to weigh in.

Is 12-3-30 a good workout?

The 12-3-30 workout centers on walking, and walking, in general, is a great form of lower-impact exercise, says exercise physiologist Janet Hamilton, CSCS and running coach with Running Strong in Atlanta. Regularly walking at a brisk pace offers a ton of health benefits, including strengthening your bones and muscles, boosting your balance and coordination, and preventing or managing conditions like heart disease, high blood pressure, and type 2 diabetes, according to the Mayo Clinic.

For most people, walking is typically a moderate activity, says Hamilton. But walking briskly at a steep incline—which is what the 12-3-30 workout entails—will probably feel more like a vigorous activity for most folks. "You have to be in pretty decent shape to go at that pace and that incline for 30 minutes," exercise physiologist DeAnne Davis Brooks, EdD, associate professor in the department of kinesiology at the University of North Carolina Greensboro and USATF Level 1-track coach, tells Health. That's because when you walk at an incline compared to flat ground, there's more gravity resistance trying to pull you back down, and your muscles—particularly the muscles in your butt and the backs of your legs—have to work extra hard to overcome that added force. As a result, your heart will automatically work harder, making the activity a cardio challenge, too.

By that measure, the 12-3-30 can be a good way to ramp up the intensity of regular ol' walking, says Brooks. It may be a solid pick for people who can't do high impact activities like running, but still want a more vigorous routine, she says. Moreover, the 12-3-30 is very straightforward. You can simply hop on the treadmill, set it to the correct incline and speed, and then you're good to go.

Another plus of the workout: If you do it five times a week, which is the frequency Giraldo does (according to her TikTok video), you'll meet the recommendations laid out in the government's Physical Activity Guidelines, says Brooks. These guidelines urge adults to get at least 150 minutes of moderate-intensity activity a week, or at least 75-minutes of vigorous-intensity activity a week.

Now, about those weight-loss claims: Weight loss is a little bit more complicated than just a single workout. If your goal is to lose weight, you need to burn more calories than you consume, and a healthy weight loss program will ideally combine exercise with diet modification, Selina Shah, MD, board-certified sports medicine and internal medicine private practice physician with Bass Medical Group in Walnut Creek, California, tells Health.

In that case, the 12-3-30 workout could be part of a healthy weight loss program, but Shah points out that any type of exercise can fulfill that role. Also worth noting: Research reported by The New York Times suggests that if you want to lose weight with exercise, you should aim to work out for 300 minutes a week. The 12-3-30 workout, unfortunately, doesn't quite meet that standard—even if you do it every day (which the experts don't recommend; more on that in a minute).

Are there any risks or drawbacks of the 12-3-30 workout?

The 12-3-30 workout offers some legit benefits, but is it a miracle workout? No, believes Brooks. There are plenty of other workouts you can do that will deliver a similar metabolic demand, says Hamilton, including bicycling at a moderate effort, playing a game of singles tennis, or swimming at a moderate pace.

Plus, the 12-3-30 is not without risks. "Any time you walk up that steep of a grade, that's a lot of load on your lower back," explains Hamilton. The workout also demands a lot of your hamstrings and calves, she says, so you could potentially strain these muscles if you jump into the routine without properly preparing your body. People with knee problems would likely struggle with the 12 percent grade, adds Shah. And if you don't have strong enough muscles in your hips, thighs, and core, you could aggravate underlying issues in your knees or ankles, or increase your risk of injuring these joins, she adds.

There's also the simple fact that walking inside on a treadmill set at a fixed incline doesn't deliver the same benefits as walking outside on varying terrain. For example, walking on uneven ground—say, a trail with rocks and roots—will challenge your balance and work the muscles in your lower legs more than if you were walking on the predictable surface of a treadmill, says Hamilton. Moreover, walking outside provides doses of fresh air, sunlight, and changing scenery—perks you definitely won't get on the treadmill.

Lastly, though the 12-3-30 can be part of a workout routine, Shah doesn't recommend it as your only form of exercise. "It's important to develop and use different muscle groups," she says, as that will reduce your risk of overuse injury and enhance your overall fitness. Mixing up your fitness routine will also help you maintain motivation and decrease boredom, adds Brooks.

How to safely try the 12-3-30 workout

Interested in trying the 12-3-30 workout? Ease yourself into it, the experts say. Otherwise, you could increase your risk of injury.

To start, Hamilton recommends making sure you're able to walk 30 minutes a day on normal terrain without any pain in your muscles or joints. Once you can comfortably do that for two to three weeks, incorporate rolling inclines several times a week. After one to two weeks at that level, gradually incorporate longer and steeper inclines. A good rule of thumb, according to Shah, is to increase the intensity of your workouts by about 10 percent each week. If, at any point, you're sore or experiencing pain, you should not progress to the next level, advises Hamilton. Instead, wait until the soreness or pain subsides (and if it doesn't, see a doctor).

When you're ready to try the 12-3-30, pay attention to your form. Walk with your arms swinging opposite your legs, and do your best to keep your hands off the rails or the front display of the treadmill, says Brooks. [If you're struggling to balance, you can hover your arms over the rails or lightly rest your fingertips on top, says Brooks—just don't support your bodyweight on the rails.] "The more you can mimic actually walking on your own power, the greater the fitness benefits will be," explains Brooks. "Your heart rate increases, the intensity increases, you're burning more calories that way."

As you do the 12-3-30, listen to your body. If you feel like you can't catch your breath or maintain good form, dial down the intensity. And if 30 minutes feels too long, try 10-minute bursts three times a day, suggests Hamilton. If the 12-3-30 becomes a regular part of your routine, make sure you pencil in other forms of exercise and regular rest days so that you reduce your risk of overuse injury. Hamilton also suggests regularly doing gentle stretches to help maintain flexibility in your calves, glutes, quads, low back, and hamstrings.

The bottom line

The 12-3-30 treadmill workout is all the rage right now on TikTok, and there are some legit benefits to it. It's not, however, a magic pill for weight loss or general fitness, so if you want to give it a go, it's important to stay grounded with your expectations and ease into it safely.

Also important: Though Giraldo—and many of her followers—seem to love the 12-3-30, it might not be your cup of tea. And that's OK. "Not everyone is gonna get that emotional high from the activity," says Brooks. The good thing is that there are plenty of other exercises out there you can try.

"If somebody asks me, what's the best exercise? My answer is always whichever one you will do on a regular basis," says Hamilton. "Find something you enjoy and do it."

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