Year-end fitness trend reports are in, and one workout is a clear winner: Pilates.

For the second year in a row, the non-cardio system of body conditioning exercises was the No. 1 workout of the year with Class Pass, according to its 2024 Look Back Report, which showed an 84% rise in Pilates bookings over 2023.

A year-end report by fitness tracker Whoop also found a “significant rise” in Pilates (while HIIT fitness was down by 21%), and a recent report from Technavio found that Pilates home equipment like the Reformer could soon replace living-room treadmills, projecting the global Pilates equipment market size growing by $146.3 million from 2024 to 2028.

Gen Z, which values mind-body connection—something organic to a Pilates workout—has been a significant driver of the trend, say many in the business. “The difference now is the young women, which is very exciting for those of us who have been in the industry a long time,” Zayna Gold, a Boston-based master instructor and longtime studio owner who has been teaching Pilates for 30 years, tells Fortune.

And with all the known health benefits of the decades-old workout—from increasing core strength to decreasing back pain—it’s no wonder so many people are finally catching on.

First, what is Pilates?

Created by German physical education advocate Joseph Pilates, who immigrated to New York in the 1920s and set up the first Pilates studio in New York City in 1926, the workout first attracted dancers recovering from injuries.

A series of about 50 structured, repetitive exercises done either on a mat—as Joseph originally created them—or on the bed-like Reformer, which he created to assist with the workout, focus on controlled breathing, core strength, alignment, and muscle engagement.

All Pilates exercises flow from the “five essentials”—breathing, cervical alignment, rib and scapular stabilization, pelvic mobility, and utilizing the transversus abdominis (deep side abdominal muscles).

What are the health benefits of Pilates?

A 2023 systematic review of randomized controlled trials found a slew of likely benefits for women: that Pilates may improve quality of life while lowering pain and disability, and also increase flexibility, strength, mobility, respiratory rate, and balance. Below, five highlights.

Improved cognitive function and sleep quality

A 2020 study found that Pilates may improve cognitive function in post-menopausal women, while and earlier study discovered it did something that could indirectly improve cognitive function: improve sleep quality.

Decreased pain

Pilates has been shown to decrease hip pain in pregnancy (not to mention better birth outcomes) and also decrease menstrual pain and joint pain.

“It works your back body muscles just as much as your front body muscles, and improves spinal health, joint health, and can reduce pain from arthritis,” says Gold.

Increased strength and posture

“Pilates really puts an emphasis on alignment and posture, and your muscles and joints are going to be healthier when you stand up straight rather than stooping over—as happens with age and with using devices,” says Gold.

Various studies have found Pilates to be effective on posture, and in the prevention of neck-shoulder disorders. It’s also been found to improve strength—of the pelvic floor and of the core, the muscle groups in your trunk responsible for posture and stability.

Mental-health benefits

Finally, Pilates has been shown to have psychological benefits in addition to physical. There is some evidence that the workout helps to decrease stress, which Gold says can help you feel centered throughout the day.

“You learn that you can have control over your ability to center yourself—and how you can find your center and take that with you when you leave the studio,” she says.

And while yoga might be the workout that’s most widely known for emphasizing mindfulness, the precision of Pilates does that, too.

“We go all in on being present with your body and your mind—serenity, centering, and really feeling in your body,” says Gold. “What I hear over and over is, ‘I have always felt like I needed to look beautiful, but I feel beautiful when I do Pilates.’ You feel beautiful from within.”

More on fitness:

This story was originally featured on Fortune.com