The 12-3-30 Workout Is All Over TikTok, So We Asked a Trainer If It Really Works

For the uninitiated, TikTok is a digital treasure trove full of tips, tricks and I-tried-its galore. The most recent trend to take over our feeds is the viral treadmill routine known as the 12-3-30 workout. The popular cardio sweat sesh involves setting your treadmill incline to 12 percent and then walking at 3 mph for 30 minutes straight. (12-3-30, get it?) On TikTok alone, the hashtag #12330 has garnered more than 182 million views and counting. Back in the real world, you’ve probably seen one or two gym-goers making the climb to nowhere as well. But when you get past the hype, can this simple—albeit catchy—formula really help us build strength, lose weight and increase our overall fitness? We reached out to Anna Victoria, Fit Body App founder and certified personal trainer, for her honest thoughts and expert advice.

And she’s not the only one. A quick scroll through TikTok or YouTube and you’ll find hundreds of reviews singing its praises (more on that later).

If you’re curious how this formula came to be, you’re not alone. Back in 2020, Giraldo told today.com that she wanted a routine that made her break a sweat but didn’t involve any running. "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."

A little random in design? Yes, but not totally off base with the basics of exercise science. In fact, most fitness professionals already know the 12-3-30 workout by another name entirely: low-intensity steady-state cardio or LISS.

At its core, the 12-3-30 routine is a walking workout, and walking (as we now know) is a form of low-intensity steady-state cardio. “There are immense health benefits of doing consistent LISS for all fitness goals like weight loss, strength training and just maintaining cardiovascular and overall health,” Anna Victoria tells us. According to the Mayo Clinic, other physical and mental benefits include increasing your cardiac and respiratory function, improving your balance and endurance and boosting your mood and sleep quality.

Walking—on a treadmill or outside—is one of the most simple and effective workouts we can do to remain healthy throughout our lives. Upping the incline from 0 to 12 simply adds resistance, helping you increase your heart rate and muscle engagement (particularly in your calves, glutes, quads and hamstrings) without changing your speed.

“One of the things I love most about LISS cardio is that it’s easy on the joints,” Victoria says. “And you can do LISS several times a week with minimal injury risk when compared to high intensity or high impact cardio.” She cautions, however, that to maintain the low impact nature, your heart rate needs to stay within 50 to 65 percent of your maximum BPM (beats per minute)—to find your max heart rate, simply subtract your age from 220.

Though the benefits are there, Victoria cautions that the 12-3-30 workout shouldn’t be the only form of exercise in your routine. “Low impact strength training would be a great addition for those who love the 12-3-30 workout,” she explains. “Not only will it be great for their joints and strengthening the muscles around them, but strength training itself helps to improve bone density, something cardio does not do.”

Of course, too much of a good thing can have the opposite effect. “While there are minimal risks with LISS cardio, any repeated exercise day after day can contribute to overuse injuries,” Victoria says, “especially when it involves walking on such a high incline.” And that 12 percent incline is no small jump. Rather than diving in headfirst, Victoria suggests slowly working your way up to an incline that feels challenging but doable. “I don’t think the steep incline of 12 percent is necessary,” she explains, “but it also isn’t harmful. You can do a lesser incline and still achieve the same LISS heart rate zones and get an amazing cardio workout in.”

Slowly working your way up the proverbial hill will also help you avoid potential muscle strains in your feet, calves and shins. A pulled calf could leave you sidelined for weeks, and if you have limited ankle mobility or are recovering from a past injury, you could be at greater risk for a strain. Easing your way in (as well as incorporating a daily warm-up and cool down) will better help you reach your goals while staying healthy.

Almost as ubiquitous as the workout itself are the accompanying "before and afters" users post online to share their 12-3-30 results. Innocent as they may seem, these types of videos typically end up being more harmful than helpful, leading viewers down a toxic path of anxiety and comparison.

By design, the "before and after" posts imply that one outcome is more desirable than the other. In addition to facilitating unhealthy comparisons, they also set misleading and unrealistic expectations—in this case, associated with the 12-3-30 workout. Though it's true our physical appearance is inherently tied to fitness, that's only one component of our overall health, and a 15-second video flashing a toned tummy and perky butt doesn't give you the whole story. A lot can happen between those two moments in time, and our bodies are constantly changing. The 12-3-30 workout is not a miracle pill, so take those clips with a grain of salt (or, honestly, avoid them altogether).

The 12-3-30 workout offers up some serious health benefits. It increases your cardiovascular endurance while building strength and may even help contribute to weight loss if paired with a well-balanced diet and lifestyle. But is it the messiah of all exercises here to change how we work out forever? Not so much. “My honest opinion is that it’s nothing new,” Victoria says. “It’s simply LISS cardio being repackaged as a new, trendy workout. But that’s often how fitness trends happen,” and we are all for anything that gets people up, out and moving their bodies. Thanks to TikTok, the 12-3-30 workout has opened the door to the fitness world for many who thought they’d never find a way in.

It may be a social media buzzword, but the one thing we can’t deny? It sure is catchy.