How to Optimize TikTok's "12-3-30" Cardio Workout

Of the many viral workouts to emerge from TikTok over the years, perhaps the most popular is the “12-3-30” cardio workout, a treadmill endurance challenge.

Here’s how it works:

Elevate the treadmill to a 12% incline
Set the speed to 3.0 mph
Walk for 30 minutes

Invented by a content creator named Lauren Giraldo, the workout has racked up millions of views and supportive comments, with followers claiming that the regimen helped them gain focus and lose weight in the gym. One person wrote: “Has actually changed my life and body!!” Another shared: “Yes!! This is how I manage to stay in shape while working 12-14 hour days. I do this three times a week.”

Strong testimonials, both. Is 12-3-30 all you need to get into the best shape of your life? We’d say…not really. But it is an excellent place to start. Here’s what works about the workout, and how to make it even ~~harder~~ better.

Why We Like It

Reading that workout prescription, it seems a little…simple, no? But that’s probably why the regimen took off in the first place. Fitness thrives on clear-cut packaging.

(Sidebar: I sometimes wonder if this is why track workouts struggle to find a footing with casual runners. Even the not-so-nuts iterations have titles that look like math problems: 3200@10K + 1600@5K + 600@maxHR w/ 400m rest in between each.)

At the ed of the day, 12-3-30 is a memorable brand with a straightforward conceit. For treadmill newbs, it saves you the time of sifting through the machine’s pre-set workouts, or toggling up and down on the controls until something feels right (or, you know, something that feels comfortable).

This challenge is a half-hour uphill walk at a decent clip. I don’t care who you are — that’s going to elevate your heart rate and push you towards your lactate threshold. The time allotment guarantees you’ll hone your oxygen intake, while the elevation functions as added resistance, giving you a chance to tone your glutes, quads, hamstrings and calves. (Check out this chart for more on that point.)

The Best Practices for Improving Your “Cardio Recovery”

Plus, a primer on what the biometric even means

How to Tinker With It

How often should (or could) you do a workout like this? I wouldn’t recommend performing 12-3-30 more than four times per week, or every other day. Ideally, this is a sort of “back-pocket workout” that everyone should have handy on a bad-weather day, or a busy day where they need to smuggle a workout into the schedule.

If you perform 12-3-30 five times a week, you’re either A) going to get sick of it (mental burnout), or B) going to get used to it (physical plateau).

That being said, it’s a fantastic foundational piece for building cardio and strength. Just last week, I was walking through the gym when I saw a guy chugging up the StairMaster and hoisting two five-pound kettlebells above his head. That’s what I’m talking about. Add a weighted vest, for instance, or a backpack with a 25-pound plate inside of it, and all of a sudden you’re rucking. Up the elevation or speed and cut back to timed, short-burst interval in order to create a circuit workout.

It’s understandable, when a workout arrives this turnkey, that online users declare it a “lifestyle” and vow to perform it as often as possible, for as long as possible. But these simple workouts are best used as an on-ramp to more ambitious and, quite frankly, more fun fitness schemes.

If you build strength with your legs inside in winter, perhaps you’ll feel more confident tackling a real hill workout — as in, one outside, with rocks and roots — in the spring and summer. Or, upon building up your VO2 max in a predictable setting, you might be inspired to get back into running, cycling or rowing. The 12-3-30 workout is just the first lily pad back to the active lifestyle you deserve.