What's the 12-3-30 Workout, and Why Is Everyone (Still) Obsessed? I Tried It to Find Out

When I first heard about the 12-3-30 workout — an incline walking workout you do on a treadmill — I was only mildly intrigued. I prefer walking in the quiet, hilly woods near my house with my dogs since it's a great workout and essential for my mental health. But sometimes the weather doesn't cooperate, so the 12-3-30 workout seemed a great indoor workout option.

Not to mention, it's all over social media: videos captioned with 12-3-30 have raked up nearly 135 million views on TikTok alone. So I also wanted to see what all the fuss was about.

What Is the 12-3-30 Workout?

The 12-3-30 workout is a treadmill workout where you set the incline to 12 percent, the pace to three miles per hour, and you walk for 30 minutes. Yes, it's that simple.

Influencer Lauren Giraldo first introduced the 12-3-30 workout on YouTube in 2019, but it didn't become popular until Giraldo posted a TikTok about it in late 2020, crediting it for helping her lose 30 pounds and keep it off for two years. The workout has since gone viral — and stuck around for years. People all over social media call are calling themselves "12-3-30 girlies" or "12-3-30 babes" — sharing their love for the workout, how they've modified it, and also their 12-3-30 results.

12-3-30 Workout Benefits

Social media users love the workout because it's straightforward — no interval timer or further instruction needed — and because it offers a challenging yet low-impact way to get in some cardio. That's right: the 12-3-30 treadmill routine is great for your cardiovascular health, as it gets your heart rate up as much as going for a jog, without the impact on your joints. In fact, research shows that incline walking may even help strengthen the knee joints.

The steep, 12-percent incline makes your body to work harder than walking on a flat surface, explains registered dietitian and NASM-certified personal trainer Nicole Rodriguez. This places more demand on your body, forcing it to expend more energy and getting your heart rate up. For example, a small 2015 study found that the metabolic cost (aka calorie burn) of walking increased by 17 percent when set at a 5-percent incline, and by 32 percent when set at a 10-percent incline when compared to walking on flat ground.

The 12-3-30 workout also has muscle-building benefits: that same 2015 study found that incline walking increases activation in many of the muscles in the lower body compared to walking on flat ground. Specifically, walking on an incline strengthens your glutes, quadriceps, hamstrings, and calves more than walking on a flat surface.

12-3-30 Workout Risks

All workouts come with some level of injury risk, and the 12-3-30 workout is no different. "I would deem this safe with physician's clearance," Rodriguez says, but if you're struggling with knee pain or injuries of any kind, this workout may not be right for you — and that's OK!

To help prevent injury while incline walking, experts at Texas Health recommend keeping your posture in mind: stand up tall, engage your core, and avoid slumping forward or leaning your weight onto the handrails.

The 2015 study found that adding an incline changes your walking gait, so your muscles may not be ready for this movement if it's new to you. If you're new to steep-incline walking workouts, you should ease into it to avoid injury or strain on your muscles. Doing too much too soon can put you at risk of an overuse injury (when tissue is damaged due to repetitive demand over a period of time), according to the Hospital for Special Surgery. It's best to gradually build up the incline, speed, and time as you're ready, taking several weeks or months if you need.

What Happened When I Tried the 12-3-30 Workout

I decided to try the 12-3-30 workout for two weeks, doing the workout five times a week, per Giraldo's recommendation. I wanted to see how this walking workout compared to the HIIT workouts, running, and rowing I'd been doing in the past few months. Could a walking workout really be as effective? Keep reading to hear about my 12-3-30 workout results.

— Additional reporting by Lauren Mazzo

My 12-3-30 Workout Warmup
Getty | Emilija Manevska

My 12-3-30 Workout Warmup

Before trying the 12-3-30 workout, I had been rowing 10,000 meters regularly (which takes about an hour). I didn't want to lose my rowing endurance completely, so I cut my rowing workout in half (5,000 meters), and I'd do that before this walking workout. I found it helped to warm up my lower back, glutes, and hamstrings for the steep 12 percent incline. After getting off the rower, I did a couple of minutes of stretching before getting on the treadmill.

Then I'd hop on the treadmill and warm up a little. I'd walk with no incline at a pace of 2.0 mph for a few minutes, then I'd increase the incline to 12 for a few minutes (still walking at 2.0 mph), and then I'd officially start the 12-3-30 workout.

Even if you're not going to do something like rowing beforehand, it's a good idea to do a full-body warmup before hopping on the treadmill. Then spend a few minutes walking on flat ground before gradually increasing the incline to 12 percent.

What Is the 12-3-30 Workout Like?
POPSUGAR Photography | Jenny Sugar

What Is the 12-3-30 Workout Like?

When I tried the 12-3-30 workout, I'd already been rowing five to six times a week, and before that, I was used to running, strength training, and walking my dogs in the woods a few times a week. So, frankly, I thought this walking workout would be really easy.

I was so wrong. The first day, my heart rate increased much higher than it does when I'm rowing or running (as reported by my Apple Watch), which made me realize I could push myself harder for both. Walking on an incline actually felt harder than running on a flat surface, because I couldn't just use momentum to bounce off the balls of my feet to keep my pace. There were several minutes when I had to hold on to the treadmill handles, and I even had to hop off a couple of times because my calves were getting so tired. It was humbling to get my butt kicked by a walking workout that I assumed would be easy. By the third day, I was able to walk without stopping, but on the fourth day, I had to stop just short of 30 minutes because my foot started to hurt. (This is exactly why Rodriguez recommends talking it slow at first!) I talked to my physical therapist, who told me to make sure I wasn't heel-striking (stepping and landing on my heel instead of the ball of my foot).

I took two days off to rest and then was able to finish off the week without any foot pain. The following week, I did the 12-3-30 workout four days in a row, rested for one day, then did two more days of the workout. After my foot started to hurt again on day four, I switched to my most supportive running sneakers, took more time to warm up with actual walking, and was more mindful about how my feet landed with each step. Taking a few extra minutes to stretch my calves and feet after the workout also helped.

By the second week, the 12-3-30 workout was still feeling intense, but in a fun way. I loved how I could swing my arms harder to elevate my heart rate or hold the handles if I wanted to tone down the intensity. I also loved how I could set the treadmill and just forget it, allowing this to be a very meditative form of movement.

I noticed that when doing these walking workouts, setting the pace to 3.0 mph forced me to keep that speed up. When I'm rowing, I'm in charge of keeping my pace, and on the Apple Watch, I could see that my heart rate range was about 20 BPM (beats per minute) lower than during the 12-3-30 workouts.

How Many Calories Does the 12-3-30 Workout Burn?
POPSUGAR Photography | Jenny Sugar

How Many Calories Does the 12-3-30 Workout Burn?

Warning: some things discussed in this slide may be triggering to those with a history of disordered eating or compulsive exercise.

Everyone's body is different, so the number of calories you burn during the 12-3-30 workout will vary from my experience. However, when I did the 12-3-30 workout, the treadmill readout said I burned about 195 calories. But I also tracked each workout over the two weeks with my Apple Watch, which noted that I burned a range between 210 and 230 total calories each time. For comparison, for me, a 30-minute rowing workout at a moderate pace burns around 205 calories, a 30-minute outdoor run burns about 240 calories, and a 30-minute, chill-paced outdoor walk around the block burns about 140 calories.

It's important to remember that workouts are important for so much more than burning calories. Exercise imparts so many benefits for your physical and mental health that make it an invaluable part of living a healthy lifestyle. While a lot of people come to the 12-3-30 workout because of its touted weight-loss benefits and because they're curious how many calories the 12-3-30 workout burns, it's also helpful to remember how strong it makes your legs and heart, and how great the endorphins feel.

My 12-3-30 Workout Results
POPSUGAR Photography | Jenny Sugar

My 12-3-30 Workout Results

Over the course of the two weeks, I definitely started to notice results from the 12-3-30 workout. Doing this walking workout inspired me to use my treadmill desk a little more. And because of the freezing temps in Vermont (where I live), I wasn't doing any outdoor walks, so the 12-3-30 workout also felt like a good replacement for that activity. And just like my outdoor walks, I loved the meditative aspect of walking at a consistent pace without having to think about it.

I also noticed that walking on a 12 percent incline really targeted my glutes and hamstrings. Rowing also majorly works those muscles, so I was shocked to notice my legs and glutes felt stronger after incorporating the 12-3-30 workout into my routine. The 12-3-30 workout also made me feel stronger overall, which I noticed when walking hills in the woods by my house, backcountry skiing, pulling my kids up a hill in a sled, or when doing dumbbell squats and lunges.

Who knew a simple walking workout would have this many benefits? Considering my 12-3-30 results, I'll definitely continue to throw the workout into my weekly fitness plan to keep my muscles guessing.