A personal trainer gives insight on the viral treadmill workout and if you should try it.
Smiling senior lady walking on treadmill at gym
Credit: Getty Images / InnerVisionPRO

If you've scrolled social media recently, you've probably seen someone raving about the "12-3-30" workout. This viral cardio routine requires just 30 minutes and a treadmill—and no running. The hashtag #12330 now has over 145 million views on TikTok, and thousands of fans giving it a whirl every day. Its simple formula touts many potential benefits, like building strength, increasing stamina and aiding weight loss. Almost sounds too good to be true, right? To get the scoop on if it actually works, we consulted Julie Floyd Jones, a personal trainer and wellness specialist.

What Is the 12-3-30 Workout?

The 12-3-30 workout was coined by 24-year-old social media maven and YouTuber Lauren Giraldo. It consists of setting a treadmill to a 12% incline and walking at 3 miles per hour for 30 minutes. Sounds easy enough. Well, according to hundreds of commenters, it's actually "a lot harder than it seems." Giraldo first shared the treadmill routine in a 2019 YouTube video, but it wasn't until she posted it to Instagram and TikTok in 2020 that it gained traction. In a 37-second TikTok video, she claims this routine helped her lose 30 pounds and overcome gym intimidation.

What Are the Potential Benefits of the 12-3-30 Workout? 

Walking has many benefits of its own—like keeping blood sugar in check, strengthening the heart, boosting mood, contributing to weight loss and even helping to reduce risk of dementia. Plus, it's more gentle on the joints than other cardio exercises, like running. "[The 12-3-30 workout] is an easy formula to remember," Floyd-Jones says. "It only takes 30 minutes, and while it is challenging because of the incline and duration, it is simply walking—which is attractive to those who don't enjoy running or who are unable to run."

Adding the 12% incline intensifies this treadmill routine and drives up heart rate, mimicking an uphill hike. "When we have to climb a hill it intensifies the workout—increasing heart rate, respiratory rate and potentially caloric expenditure," Floyd-Jones says. "You are definitely going to improve cardiovascular health and cardiovascular endurance and strength. Due to the incline, you should also improve strength in your lower body." Working against gravity on an incline makes you winded faster than, say, a walk in a park. So, short answer: Yes. This workout does have its benefits, but it shouldn't be your sole source of physical activity—more on that later.

How Do You Do the 12-3-30 Workout?

First things first, fuel up. A general rule of thumb is to eat 45 minutes to an hour before you start a workout—especially when it comes to cardio. Or, wait until afterward, if your body prefers it. Either way, opting for a snack that wields a combo of carbohydrates and protein is best.

The old adage, "Slow and steady wins the race," rings true with the 12-3-30 workout, too. Resist the urge to jump in too quickly, and take time to ease in. Floyd-Jones recommends beginning with pre-workout stretches to activate your glutes, calves, hamstrings and hips. Then, gradually work your way to the treadmill. "When I do any type of treadmill work with my clients, I always have them do the first couple of minutes flat–at 0% grade–to acclimate to the treadmill and begin to warm up," she says. "Then, I start to adjust the incline, and potentially the speed." It's good to push yourself, but also make sure you're listening to your body—duration and pace can always be adjusted.

You're not off the hook once the 30 minutes are up. Allotting time to recover after a good sweat optimizes benefits and lowers risk of potential injuries. "Any time you're going up an incline for that prolonged period of time, you need to take time to undo it," Floyd-Jones says. "Your muscles are working, tightening and strengthening, so then you need to go back and make sure you're lengthening them again." She suggests doing basic foam-rolling exercises and calf and hamstring stretches.

No Treadmill? Don't Sweat It.

The 12-3-30 is difficult to replicate on other machines due to the lack of incline. But upping resistance and stride on ellipticals and Arc Trainers is a good lower-impact alternative way to intensify your workout—and may even be a better option for some. "I would tell my clients to be cautious doing prolonged incline if they are dealing with plantar fasciitis, tight calves or hamstrings or low back pain," Floyd-Jones says. Or, if you don't have access to a gym or machines, simply hitting the hills outside is also a great way to get your heart pumping.

Can You Do the 12-3-30 Workout Every Day?

The Physical Activity Guidelines for Americans recommends adults get at least 150 minutes of aerobic activity per week, meaning knocking out this 30-minute uphill workout five days a week hits that requirement. Feasible, right? Although the 12-3-30 workout has its benefits, adding other elements of physical activity is necessary for a more well-rounded routine. Many fitness fans are going all-in on 12-3-30—with some even doing it every day. Floyd-Jones warns against this and recommends sticking to the 12-3-30 workout two or three days a week max. Intervening days are better spent building up other muscles—like those of your core and back—by doing resistance- and mobility-based training or body-weight exercises at home.

The Bottom Line

The 12-3-30 treadmill workout is an effective aerobic routine that gets your heart rate up, builds strength and endurance and may even contribute to weight loss when paired with a balanced diet. It's memorable and requires one piece of equipment only, making it feel achievable for many. However, it's no magic solution. For best results, stick to 12-3-30 a couple of days a week and use the remaining days to engage other muscles through strength and mobility training, a fitness class you enjoy or a walk around the block. You know your body best, so stay in tune with yourself and go at your own pace.