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Two personal trainers weigh in.

Dozens of buzzy, new workouts have found their home on TikTok. From viral dances to push-up challenges, there seems to be no end to the fitness videos that pop up on millions of users' For You Pages. Even celebs are getting in on the fun—like Hilary Duff and Carrie Underwood, just to name a few.

But now, there's a brand new sweat session making the rounds: the 12/3/30 challenge. Created by social media star and actress Lauren Giraldo, the challenge is a simple treadmill workout that promises major results.

Not to mention, the views! Already, #12330 has over 70 million views on the app, while #12330challenge has over 18 million.

Some popular TikToks featuring users trying or talking about the challenge are getting millions of likes—and it's easy to see why. The challenge only has three "rules," or steps, but it can apparently revolutionize almost anyone's fitness routine.

Many TikTokers are claiming that the workout is kickstarting their motivation to work out on a regular basis. Supposedly, it also burns hundreds of calories in under an hour and has even helped some users lose weight. With thousands of transformation videos to watch, the evidence is almost overwhelming.

So, does it really work—or is the 12/3/30 method just too good to be true? WH tapped two personal trainers to unpack the risks and potential benefits of the challenge. Here's everything you need to know.

The steps are easy. First, set the treadmill to an incline of 12, and set the speed to 3 miles per hour (MPH). Then, walk for 30 minutes—and yes, that's really all there is to it! Users also recommend doing the workout five days a week.

For starters, the 12/3/30 method is a total lower-body workout, says Haley Gott, a certified personal trainer. "It's a great way to activate multiple muscle groups in your legs," she adds, including your quads, your hamstrings, your glutes, and your calves.

It's also good for cardiovascular health. So if your current cardio routine needs a shake-up, the 12/3/30 workout could be a helpful addition. And, Gott confirms those claims that the method burns hundreds of calories are true—anywhere between 400 and 800 to be specific, although the exact number will vary depending on your current activity level.

Plus, exercise in general, including this workout, can help support your immune system and help you sleep better, says Gail McGhie of Gail McGhie Fitness.

Possibly, Gott says, although she stresses that any weight loss from doing the 12/3/30 method would vary from person to person. (It's also important to note that weight loss mostly requires eating healthy foods in a calorie deficit.)

"Everyone's heart rates are different," she says, "so ultimately, if you're trying to lose fat, then you should be paying attention to your personal heart rate zones." Heart rate zones represent how fast your heart should beat during different kinds of exercise for the most efficient workout. (You can find out how to calculate yours here if you're curious about this type of training style!)

Regardless, Gott says, "I think incorporating it into your weekly routine could be beneficial."

This workout isn't for everyone. "Walking on a steep incline can really aggravate your lower back," Gott notes. "So paying attention to your posture is really important." She also says it's crucial to hold on to your core strength.

Because the incline is cranked up so high and a treadmill is a flat surface, McGie confirms that this isn't a low-impact workout. "It just really stresses the body in some good ways and some bad," she says.

Gott also mentions that the method could lead to injuries for anyone with hip, knee, or ankle issues. "If you have those issues, or you experience low back pain, you should start this workout at a lower incline," she says. You can always work your way up, "but you can still challenge your cardio and your legs at a lower incline."

And, it's important to pay attention to your body as you walk. "When we start to get tired, our bodies will naturally start to compensate," Gott says. As you get tired, your body might start relying on other muscles to help you power through (like the ones in your lower back, Gott explains). She says this can put stress on those muscles and cause discomfort or a change in your stride.

"You don't even notice it, but when you're tired, your body just does its own thing," she adds. So, if you're feeling any aches and pains beyond your usual post-workout tiredness, consider lowering the treadmill's incline, taking a break, or stretching your muscles out.

Afterward, Gott encourages stretching. "Because you're exhausting your legs for 30 minutes in the same exact fashion, a deep stretch afterwards is really important," she says. She recommends focusing on your hip flexors by moving through some lunges and static stretches.

It can, "depending on what your fitness goals are," Gott concludes. But five days a week might be a little over the top. Both Gott and McGie say that doing the 12/3/30 method for two or three days a week, when combined with other types of training, is plenty.

So, what to do on those days off? McGie suggests interval training, weight training, or even swimming. Look for exercises in the lateral plane, she says, since the treadmill only pushes your body to do one type of motion.

"I don't think there's anything wrong with this workout," Gott adds. "But it is very repetitive and it's very steep." But, "anything that gets people moving is a great thing," McGie points out. "The important part is to just really go into it gradually." (And stay hydrated!)