IE 11 is not supported. For an optimal experience visit our site on another browser.

What is '12-3-30'? The walking treadmill routine helped 1 woman lose 30 pounds

Social media personality Lauren Giraldo lost weight with her viral treadmill workout. A sports medicine doctor weighs in on how to try it safely.

Welcome to the Start TODAY Walking Challenge sponsored by Easy Spirit. Sign up for our free Start TODAY newsletter to join the challenge with Al Roker and receive daily inspiration sent to your inbox. Then, join us on the Start TODAY Facebook group for tips and motivation, to connect with others following the plan — and to get real-time advice from trainer Stephanie Mansour!

Walking has been having major moment. Spurred by its accessibility and ease, many of us rediscovered our love for the most basic of movements during the pandemic. Although indoor restrictions and lockdowns seem to be a thing of the past, walking is here to stay. It even inspired us to create a whole community around walking called Start TODAY.

Walking has many proven health benefits — from boosting your mental health, to reducing your risk of dementia, to improving cardiovascular function. So it's no surprise that one woman's treadmill walking routine quickly went viral in 2019 and continues to make the rounds on social media to this day. The fact that it helped her lose 30 pounds doesn't hurt either.

Social media personality Lauren Giraldo originally posted her “12-3-30 workout” — which she credits with helping her feel less intimidated by the gym — to YouTube in 2019, but the workout continues to gain followers as a viral TikTok video posted in November 2020 garnered more than 2.7 million likes and 12.6 million views.

“I’m not a runner, and running on the treadmill was not working for me,” Giraldo told TODAY via email. “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.”

Anyone who has ever walked an incline on a treadmill knows that it’s much harder than it looks. “It was definitely a struggle at the beginning, and it took me a couple of months to really start to enjoy the workout,” Giraldo said. “I found that just focusing on myself for 30 minutes a day was not only great for my body, but also great for my mentality. Now, it’s something I look forward to doing every morning.”

Clearly it has worked for others as well: In April 2021, Giraldo posted a video on TikTok featuring before and after pictures of other women who have lost weight by doing her workout. Since then, TikTok users continue to post impressive before-and-after results and claim that the workout not only helped them lose weight, but also tone their core and legs.

"I felt like I ran freaking 5 miles after!! I hate running so I’m happy I found this," commented one user. "My shirt is drenched when doing 12-3-30. It’s not drenched when I just plain walk w/no incline. My sweat speaks for itself," said another.

While it sounds promising for those of us who want to get the best workout we can in the shortest amount of time on the hamster wheel, it also begs the question: Is it safe? And what should we know before giving it a try?

What is the “12-3-30” workout?

Giraldo’s workout is guided by three settings on the treadmill:

  • Incline: 12
  • Speed: 3
  • Time: 30 minutes

According to Giraldo's TikTok video, she does the workout approximately five times per week and it helped her drop 30 pounds. “I obviously noticed the changes in my body, but I was most happy with the changes that I felt mentally,” she said. “I was proud of myself every day for getting on the treadmill and having my ‘me time’ for 30 minutes. I feel accomplished every time I do it.”

For Giraldo it served another important purpose: getting her comfortable stepping foot in the gym. “The thing about 12-3-30 is it made the gym so much less of a scary place. I feel confident in the gym now, and I sometimes incorporate weights and other exercises into my workout,” she said.

Is Lauren Giraldo’s '12-3-30' workout safe? What are the benefits?

At first, Giraldo couldn’t make it the full 30 minutes. “I definitely had to work up to the 30 minutes. I couldn’t get through it without losing my breath and started out by taking a break after the 10 or 15-minute mark,” she said.

Dr. Dennis Cardone, osteopathic sports medicine specialist and chief of primary care sports medicine at NYU Langone Health, told TODAY that this isn’t a workout you should jump right into.

“If someone is working that hard with this workout and they are a 20-something, young and healthy, and they are struggling, you see it was a pretty significant workout. It’s just too much too soon and it should really have a recovery day as well,” says Cardone.

That’s not to say that there can’t be benefits to adding an incline to your workout. “It certainly adds more stress to a workout in the sense that people are getting more of a workout in a shorter period of time; the muscles are working harder,” said Cardone.

But, he adds, the risks may outweigh the benefit when it comes to adding a significant incline to your workout.

“The problem is people don’t think that walking is a stressor. They think ‘what’s the big deal using an incline? I’m only walking.’ But it really is a big stressor: low back, hamstring, Achilles tendon, knee, plantar fascia … these are the areas where we see some significant injury related to inclining a treadmill,” he said. “As a general observation, anytime anybody begins or changes a workout or adds something like an incline, they have to follow the rule to do it slowly, otherwise they are certainly at significant risk for an overuse injury.”

Want to give it a try? Follow these guidelines for a safe and effective workout

“(Giraldo) did well, but most people never make it there because they will get an overuse injury and will be taken out of the game. It’s a great goal, but it’s just not realistic for most of the population," said Cardone. "If you just do one activity — we don’t have to bash just this one — but whatever activity, if you keep doing it day in and day out, it's just a set up for injury.”

So instead of jacking that incline way up, here is the safe way to try Giraldo's workout:

  • Don’t be fooled by the treadmill: “People think the treadmill is so safe; it’s not outdoors, it’s a soft, forgiving surface. But it’s not that different from walking up a hill; you’re not protecting yourself that much more by being on a treadmill as opposed to being out on a road,” warned Cardone. “Thirty minutes walking up a mountain, it’s pretty tough when you think about it. People feel a little overconfident about the treadmill.”
  • Adjust the numbers to meet you where you’re at. “Don’t incline so rapidly, maybe don’t even start at 30 minutes; 3 mph is reasonable, but maybe slow down your duration of workout and incline to work up to that," suggested Cardone. "Start flat on a treadmill, and do 0-3-30. Once that is comfortable for you, then start inclining, don’t go to 12 right away. Over 3 weeks start slowly progressing your incline, maybe 10-20 percent per week.”
  • If you're new to fitness, start on flat ground. “If someone is outdoors and starting their workout program, whether it’s walking, jogging, interval training, don’t look for a hill," said Cardone. "First, tolerate flat and once you’re doing that then you if you want to add some hills into your workout fine, but don’t go looking for hills at the start of a program.”
  • Gradually increase incline: “Slowly progress your incline, start at the lowest setting and it’s a gradual increase, like any other workout in terms of increasing mileage or intensity,” said Cardone. “This workout starts at a 12-degree incline, so I’d say go at 4-degree intervals. So gradually increase it over a 3-week period to get to that 12 degrees.”
  • Don’t do it every day. “Almost whatever the routine is, the general rule is there should be a recovery day or at least alternating with some other activity in order to try to avoid overuse injuries," said Cardone. "I wouldn’t discourage people from doing some sort of activity most days of the week, just not the same activity. Have a recovery day where you are doing some sort of alternate activity, maybe that might be the elliptical trainer, a bicycle or in the swimming pool, whatever you have available."
  • Supplement with strength and stretching. The bent posture of walking uphill places stress on your low back, Achilles tendon, calf muscles, plantar fascia and hamstring muscles, said Cardone. “Those are stubborn problems and people don’t want those kind of injuries, once they kick in, they are tough to treat," he said. He suggested doing core-strengthening exercises as well as stretching those areas specifically to help reduce your risk of injury while walking or running.
  • Consider something lower impact. If you are just getting into fitness, Cardone advised starting with lower-impact workouts. “Bicycling, elliptical trainer, swimming, cross-training type activities, are even safer. Those are great activities to start a workout routine and build up your cardiovascular endurance; you’re not doing a lot of impact, it’s a little more forgiving on the joints and also on muscle tendons," he said. "So maybe do the treadmill 2 or 3 days a week and the other days these other activities; that is going to keep people out of trouble.”

Bottom line

Even if you’re following these guidelines, the workout should still be done at most, every other day, alternating with other lower-impact activities.

In order to get the benefits you seek from any exercise — whether that be weight loss, toning or overall health — the key is to find a program you can stick with, said Cardone. Which means it not only needs to be safe, so you’re not sidelined by an injury, but “it has to be something they enjoy, and if they are only doing one activity they are going to burn out, not just physically, but mentally,” he said.