What Is the "12-3-30" Incline Walking Workout?

Here's what fitness experts want you to know about the trendy treadmill workout before you try it.

Whether it's keto and Whole30 or CrossFit and HIIT, there's no denying that wellness lovers are always on the lookout for a new food or fitness trend. One trendy workout you may have heard about is incline walking, specifically the "12-3-30" treadmill workout created by lifestyle influencer Lauren Giraldo. Giraldo credits the simple incline walking routine with helping her feel more comfortable at the gym. Don't mistake simplicity for ease, though — this exercise still packs a punch.

The social media personality first shared the incline walking workout on her YouTube channel in 2019, but it didn't go viral until she posted it on her TikTok in November 2020. The concept of the workout is simple: You hop on a treadmill, set the incline to 12, and walk for 30 minutes at 3 miles per hour.

Giraldo came up with the formula by happenstance, she told TODAY. "I'm not a runner, and running on the treadmill was not working for me," she said during an interview with the news outlet. "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." (

But it took a while for Giraldo to do the workout at full capacity, she continued. "I definitely had to work up to the 30 minutes," she said. "I couldn't get through it without losing my breath and started out by taking a break after the 10- or 15-minute mark."

After building her stamina and doing the workout about five days a week, Giraldo lost 30 pounds and has been able to keep the weight off for two years, she revealed in her TikTok video. "I used to be so intimidated by the gym and it wasn't motivating, but now I know I do this one thing and I feel good about myself," she said in the clip. "And I look forward to it. It's my me time."

The simplicity of Giraldo's "12-3-30" workout sounds enticing, but is it right for you? If you live a relatively sedentary lifestyle, it's probably not a good idea to jump on the treadmill and tackle such a steep incline for such a long period of time right off the bat, says Beau Burgau, C.S.C.S, founder of GRIT Training.

"Walking on an incline can be very taxing on your body," explains Burgau. "And doing it on a level-12 incline for 30 minutes straight is a lot. You have to make sure that you're building up to such intensity in order to avoid injury and overstraining your joints and muscles." (

This is especially important for people who are new to fitness, says Burgau. "You should be able to walk on flat ground for 30 minutes straight before adding any kind of incline on the treadmill," explains the trainer. Once you've mastered that and it starts to feel easy, you can progress, but conservatively, he says.

Beginners should start at a level-3 incline and walk for a short period of time — maybe even as little as five or 10 minutes, based on your fitness level, recommends Burgau. "Slowly build up to that 30-minute mark, if that's your goal, before upping the ante." This gradual progression could take you anywhere from several weeks to a few months, he adds. "It's going to be different for everyone." (

Another way to build up to the "12-3-30" incline walking workout is to increase your incline on the treadmill by about 10 percent each week, suggests Duane Scotti, D.P.T., Ph.D., a board-certified orthopedic clinical specialist and founder of SPARK Physical Therapy.

As with most workouts, form is also key. When walking uphill, you're naturally in a forward flection, explains Burgau. "It shortens your chest and pec muscles and lengthens your upper back and scapular muscles," he says. Meaning, your posture is probably going to be jeopardized after a while. "You have to make sure your shoulders are back, your core is engaged, and that you're not arching your back," says Burgau. "If at any point you feel your lower back straining, stop." (

Even though incline walking workouts are a great way to rev up the heart rate, they're not necessarily something you should do every day, adds Burgau. "Just like with any workout, you really shouldn't be doing it back-to-back-to-back every single day for weeks on end," he says. "Variety is so important." Scotti agrees, recommending that beginners aim for doing the workout no more than two or three times per week.

While doing the 12-3-30 workout (or the aforementioned modifications), you can expect to predominantly work the muscles along the back of your legs, as well as your back muscles, explains Scotti. These include your erector spinae muscles (which run alongside the spine), gluteus maximus, hamstrings, and ankles. "If you strain those same joints and muscles repeatedly, especially when you're doing a high-intensity, incline-based workout, you're putting yourself at risk for all sorts of injuries, like Achilles tendonitis, plantar fasciitis, general knee pain, and shin splints," warns Scotti.

That's why it's important to switch things up, he adds. Even Giraldo told TODAY that she's started supplementing her treadmill workout with weight training and other exercises since she now feels more comfortable in the gym.

The best way to avoid injury is to stretch, stretch, stretch, says Scotti: "It's so important to warm the body up and activate [your muscles] before doing a workout like this." Given how taxing this exercise can be, consider doing at least five minutes of dynamic stretching beforehand and five minutes of lower-body static stretching afterward, suggests Scotti. "Make sure you're holding the stretches for at least 30 to 60 seconds each," he adds.

At the end of the day, if your goal is to lose weight, there are plenty of other ways to get there, says Burgau. "I struggle recommending going all the way up to a level-12 incline for 30 minutes," he says. "It's just unnecessary when there are so many other lower-impact workouts that are equally effective."

"I'm a huge proponent of doing whatever it is that motivates you," adds Burgau. "Doing anything is better than sitting on the couch. But it's important to be informed and make sure you're being safe. The key to weight loss is consistency, so find something that you enjoy doing that doesn't jeopardize your long-term health."

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