12-3-30 is a treadmill walking routine made popular by TikTok. It involves walking on a treadmill at an incline of 12 and speed of 3 miles per hour for 30 minutes.Healthcare providers recommend walking in general as a way to improve health and physical fitness.I tried the walking routine for a month, doing 12-3-30 three times a week, and found that I not only saw improvements in my body, but also my motivation to work out.
It’s seemingly impossible to scroll through TikTok or Instagram without seeing someone doing 12-3-30, the ultra-popular treadmill walking routine invented by influencer Lauren Giraldo—and sharing their results.
The gist of the routine is this: Walkers get on a treadmill and set the incline to 12 (very steep!) and speed at 3 miles per hour. They proceed to walk on that treadmill for 30 full minutes, typically emerging drenched in sweat but glowing with accomplishment.
If you consult any of the videos tagged with the #12-3-30 hashtag on TikTok—which, combined, have garnered over 430 million views and counting—you’ll see that sweat isn’t the only result of the treadmill workout. Walkers boast weight loss, improved fitness, and even a refreshed desire to exercise.
But are all of these claims true? Could doing 12-3-30 for 30 days really make me more fit and renew my vigor for working out? Surprisingly, yes—after my first day of 12-3-30, I left the gym feeling shockingly sweaty and mostly excited to see where the month would take me.
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Before You Get Started
First things first: Exercise is so important for maintaining overall health, reducing your risk of chronic disease, improving mental health—you get the gist.
For your best shot at optimal health, the U.S. Department of Health and Human Services' Physical Activity Guidelines for Americans suggests all adults get 150 minutes of moderate-intensity physical activity each week, plus two days of muscle strengthening activities.
Exercising for just 30 minutes a day—like 12-3-30 suggests—five days a week, will help you hit that 150-minutes goal.
However, while physical activity is recommended for most everyone, there are certain conditions that can make exercise difficult or potentially dangerous, especially for those who don't regularly move their bodies. As with any new fitness routine, if you have health concerns or are new to physical activity, talk to your healthcare provider to make sure you are physically able to up your daily movement.
Additionally—because 12-3-30 takes place on an inclined treadmill—people with a history of leg, knee, or back pain or problems may also want to get the OK from the healthcare provider before giving it a try.
12-3-30 Basics
All you need to do 12-3-30 is a treadmill. After whatever warm-up you've decided to do (I recommend some light stretching, and in my case, a brief walk from the apartment to the gym), set your treadmill to the following:
Incline: 12Speed: 3Timer: 30 minutes 12-3-30 Treadmill Safety Checklist
While the treadmill may be a basic piece of workout equipment, experts agree there are "right" and "wrong" ways to use the machine, whether for 12-3-30 or another treadmill workout.
Emi Gutgold, CPT, a group fitness trainer and certified Pilates instructor, advises people to remain aware of the space between them and the front of the treadmill, keeping a distance where you’re able to see your feet when you glance down.
The clip attached to the majority of treadmills also provides an additional element of safety should you slip and fall. "No one is above wearing the safety clip, even if you are just walking," Gutgold told me.
Nikki Pebbles, MS, a special populations personal trainer in NYC, noted four key things she often sees people doing incorrectly on the treadmill:
Leaning too far forward:Leaning too much on the handrails can strain your lower back. It’s important to maintain an upright posture.Holding onto the handrails tightly:Gripping the handrails too tightly can affect your natural arm swing and balance. Use the handrails for balance if needed, but don’t rely on them to support.Using excessive incline or speed:Starting with too steep an incline or too fast a speed can strain your muscles and joints, especially if you’re not accustomed to it. You should gradually increase the intensity as your fitness level improves.Not engaging your core:Neglecting to engage your core muscles can lead to poor posture and an unstable walking gait. Focus on keeping your core muscles lightly engaged throughout the workout.Wearing inappropriate footwear:Choose proper athletic shoes that provide support and cushioning for your feet. Wearing the wrong shoes can lead to discomfort and even foot or ankle issues.
There's more that goes into a simple treadmill walk than you might think. But after 12 treadmill sessions in 30 days, I can see how these tips make a difference.
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I already maintain an active lifestyle: I attend three group fitness classes a week and average at least 10,000 steps a day—but I made a few slight changes to add 12-3-30 into my schedule. I opted to do the workout three days a week for an entire month. I also cut down on the amount of group fitness classes I took.
After trying 12-3-30 on my own (and speaking to fitness experts), I realized that the benefits of the routine hinge on three things: consistency, accessibility, and an elevated heart rate—specifically zones 2–4, which is sustainable but challenging for cardio activity.
Heart Rate Zone Training
Heart rate zones monitor the intensity of your workouts (or daily activities), and are typically split into five different zones, based on a person's maximum heart rate (HRmax).
The simplest and most accurate way to find your HRmax is through what's known as the Tanaka formula: 208 – (0.7 x age) = HRmax. Using a 30-year-old woman for example, this formula would suggest that her HRmax is 187 BPM (beats per minute).
Once you've got that number, you can determine which heart rate zone you're in based on what your current heart rate is in relation to your HRmax. The zones are as follows:
Zone 1: < 57% HRmax (very light effort)Zone 2: 57%–63% HRmax (light effort)Zone 3: 64%–76% HRmax (moderate effort)Zone 4: 77%–95% HRmax (vigorous effort)Zone 5: > 96% HRmax (near-maximal or maximal effort)
Luckily, there are many devices like Apple Watches or Garmins that can tell you your heart rate zones during or after training, provided you give them accurate information.
Before stepping on the treadmill for each 12-3-30 workout, I opted to lightly stretch out my calves and hamstrings—admittedly not much, just some seated folds and downward facing dogs. I made sure to stretch after my workouts too. I can’t say for sure they improved my performance, but it’s certainly never a bad idea to stretch before exercising.
During the workout, even though I wasn't moving at a pace I'd consider "fast," I could feel my heart rate steadily rising, particularly for the first 10 minutes—after which I was dripping in sweat.
The average heart rate recorded by my Apple Watch during 12-3-30 was 164 BPM. Based on that number and my own HRmax, I hovered between zones 3 and 4—and I was winded and relieved when the treadmill clock reached 30 minutes and I could leave the 12 incline in the dust.
Though sweaty, 12-3-30 was also extremely easy to stick to and worthwhile: It doesn't take long—30 minutes is just about 2% of an entire day—it burns about 300 calories (according to my Apple Watch data), and it does (slowly and sustainably) contribute to physical fitness (shout-out to my newly toned calves).
Lily Moe
Does 12-3-30 Work?
The answer depends on what your definition of "work" is: While I wasn't tracking a specific aspect of my health (like weight loss), I still believe the challenge provided a few noteworthy results.
The 12-3-30 routine did wonders for my workout motivation. My mind tends to lean toward procrastination—but I very quickly found myself saying "You've just got to go walk on a treadmill," which made getting up and getting moving far easier than it is for a typical gym session.
The workout, though pretty difficult at first, also became easier throughout the course of my 30-day trial. Sure, I pretty consistently broke a sweat (sometimes profusely), but as time went on I felt my body adapt: My quads and calves were feeling less tight while walking on the incline, and the 3-mile-per-hour pace was tolerable.
I couldn't help but wonder: Am I a treadmill girl now?
Lily Moe
Challenges
Massive amounts of sweat aside, there were a few key challenges I experienced during 12-3-30.
The first is the pacing. I am notoriously bad at pacing myself. So while having the treadmill speed set to 3 mph helped me keep a tempo, I physically found it uncomfortable at the beginning. This did get easier over time—I found my body almost got into a rhythm.
I also found it very tempting to grab onto the handrails of the treadmill, even though I know it’s poor treadmill form. A modification to the workout at the beginning of the challenge—like lowering the incline or reducing the speed or time—would’ve been helpful.
While I was able to do the 12-3-30 challenge with sweat being my only main side effect, I'm not sure the original treadmill combination is ideal for beginners. Instead, I'd suggest starting slow and gradually increasing the incline or time (or both!) as you get more comfortable with the workout.
I'd also highly advise anyone looking to try the 12-3-30 workout to wear comfortable, reasonably cushioned athletic shoes. One day, I wore a pair of thinner sneakers that I usually wear for HIIT workouts and noticed my feet/shins were a little uncomfortable.
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Would I do 12-3-30 again or recommend it to others to try? Yes and yes—but scaling back a bit, I would recommend more walking in general, at whatever incline level and speed best suits your fitness level. Gutgold agrees: "It's walking that works, not 12-3-30 specifically."
As an active person who already walks a reasonable amount, 12-3-30 allowed me to experiment with a new workout. But I've also seen walking positively impact my fitness levels and overall well-being in the past.
Was it fun to change it up? Sure. Do I think 12-3-30 is a magic solution? No—but I think it provides the same benefits as the tried and true method of, as my dad says, walking it out.
"The 12-3-30 workout can be effective for those looking for a low-impact, time-efficient cardiovascular workout," Pebbles said. "However, like any workout, its effectiveness depends on how well it aligns with your goals and fitness level."
And if you do try it, don't forget your sweat towel!
Lily Moe is a News Editor at Health. As a former fitness coach, she has a lot of experience in trying out fitness trends, both new and old. With the popularity behind the new 12-3-30 treadmill walking routine, Lily wanted to see if it actually worked, or if it was all hype.