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When a heat wave hits, it’s time to move indoors, and doing a treadmill workout can be fun and effective. The 12-3-30 treadmill workout continues to be a favorite among workout trends since it went viral in 2020.
The workout is simple: Set the treadmill to an incline of 12 (or lower — choose a challenging incline for your fitness level) at a speed of 3 miles per hour and walk for 30 minutes.
The 12-3-30 is popular in part because there is no running required. Walking can lower your risk of heart disease, stroke and Type 2 diabetes, according to the Centers for Disease Control and Prevention.
The U.S. Department of Health and Human Services recommends moderate-intensity aerobic exercise for 150 to 300 minutes a week. Doing the 12-3-30 workout five times a week would get you into the low end of that range.
But don’t jump to five times a week all at once. Start slowly and work up to more frequent workouts if you’re just getting started, and begin at lower speeds and inclines until you know how your body will respond.
What Are the Benefits of 12-3-30?
Walking has many health benefits including improved cardiovascular health and blood pressure, reduced risk of diabetes, increased metabolism and improved mental health. It can even lower the risk of some cancers.
Since walking is lower-impact, it is less likely to cause injury than running, and walking on an incline engages your leg muscles more than walking on level ground, says fitness contributor Stephanie Mansour. “This will make for a more intense workout for your glutes, hamstrings and quads, while also increasing your heart rate.”
Is the “12-3-30” Workout Safe?
There are some risks to adding a significant incline on the treadmill, Dr. Dennis Cardone, osteopathic sports medicine specialist and chief of primary care sports medicine at NYU Langone Health.
“The problem is people don’t think that walking is a stressor,” Cardone says. But walking on an incline can be a big stressor to the lower back, hamstring, Achilles tendon, knee and plantar fascia. “These are the areas where we see some significant injury related to inclining a treadmill,” he says.
Cardone suggests starting slowly and having rest days, “otherwise they are certainly at significant risk for an overuse injury,” he says.
Physical therapist Vijay A. Daryanani, a certified personal trainer at Spaulding Outpatient Center, a hospital that partners with Harvard Medical School, says he recommends people pay close attention to their posture while walking on an incline.
“When I’m training someone, I will adjust the incline safely and with guidance to maintain posture, balance and stride. Inclining a treadmill is similar to walking up hills, which places different stresses on the musculoskeletal system,” he says.
Here’s what to know to prevent injury if you’re ready to try the 12-3-30 workout yourself:
- 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,” says Cardone. “First, tolerate flat. Once you’re doing that, then if you want to add some hills into your workout, fine. But don’t go looking for hills at the start of a program.”
- 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,” warns Cardone. “Thirty minutes walking up a mountain, it’s pretty tough when you think about it. People feel a little overconfident about the treadmill.”
- 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,” says 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.”
- Gradually increase incline: “Slowly progress your incline, start at the lowest setting and (gradually) increase, like any other workout in terms of increasing mileage or intensity,” says Cardone. Adjust the numbers to meet you where you’re at. “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.”
- Supplement with strength and stretching. The bent posture of walking uphill places stress on your lower back, Achilles tendon, calf muscles, plantar fascia and hamstring muscles, says Cardone. “Those are stubborn problems and people don’t want those kinds of injuries, once they kick in, they are tough to treat,” he says. He suggests doing core-strengthening exercises as well as stretching those areas specifically to help reduce your risk of injury while walking or running.
- Consider the impact. If you are just getting into fitness, Cardone advises 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 says. “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.”
When Did This Trend Start?
The 12-3-30 trend took off when health and beauty influencer Lauren Giraldo posted about it on YouTube in 2019 and then again on TikTok in 2020, sharing that the workout helped her lose 30 pounds and keep it off.
“I used to be so intimidated by the gym. It wasn’t motivating, but now I go do this one thing and I can feel good about myself,” she said on TikTok. “I look forward to it. It’s my me-time.”
The influencer, who is not a fitness expert, chose the numbers 12, 3 and 30 because the highest incline on the treadmill at her gym was 12, she didn’t enjoy running and three miles per hour felt like a good, brisk walking pace to her, and her grandmother always advised to exercise at least 30 minutes each day.
According to Giraldo’s TikTok video, she does the workout approximately five times per week. “I obviously noticed the changes in my body, but I was most happy with the changes that I felt mentally,” she said. The workout helped her get 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.
At first, Giraldo couldn’t make it the full 30 minutes. “I definitely had to work up to 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.
Can You Lose Weight With the 12-3-30 Workout?
Walking treadmill workouts can improve endurance and aid in weight loss if you do them consistently.
Gradual, steady weight loss of about 1 to 2 pounds per week is optimal for keeping the weight off, according to the Centers for Disease Control and Prevention.
“Generally to lose 1 to 2 pounds a week, you need to burn 500 to 1,000 calories more than you consume each day, through a lower calorie diet and regular physical activity,” according to the Mayo Clinic.
Walking for 30 minutes burns about 125 calories for a 150-pound person — and adding an incline will increase that calorie burn. So with healthy diet changes, the 12-3-30 workout has the potential to burn the calories needed for steady, gradual weight loss.
How Many Times a Week Should I Do the 12-3-30 Workout?
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.
Make sure your fitness routine is safe, so you’re not sidelined by an injury, and also “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 says.
