For people unfamiliar with it, the Pilates exercise routine may conjure up images of twisting torsos and gym junkies, but a local fitness instructor says those notions may be misunderstandings.

Reed Flanagan, a physical trainer and owner of St. Simons Pilates & Yoga on St. Simons Island, said the routine is gaining popularity, and people just starting out at the gym, as well as veteran athletes, can benefit.

“The essential premise of Pilates is that it’s a neutral spine exercise that activates the core muscles while moving the arms and legs,” Flanagan said Monday at his studio on Union Street on St. Simons Island. “It’s a resistance exercise, so it’s low-impact, works every muscle group and can help with balance, coordination and even breathing.”

Pilates, while gaining popularity, has been around for almost a century. The exercise regime was created by Joseph Pilates, a German who immigrated to the United Kingdom in 1912. Pilates worked as a self-defense instructor for detectives at Scotland Yard, but with the outbreak of World War I, he and other German nationals were labeled “enemy aliens” and sent to internment camps.

During his internment, Pilates worked as a physical therapist at a hospital. He found a way to rig springs to hospital beds for patients to use in regaining their strength.

When the influenza epidemic of 1918 hit the U.K., Pilates noted that none of the patients using his spring-bed device died, and pointed to that as proof of its effectiveness.

“A lot of the patients couldn’t move their arms, so he was doing a lot of training,” Flanagan said. “When he figured out he could attach springs with handles at the ends, that allowed the patients to work themselves out.”

The innovative device eventually became known as a Pilates reformer — a machine widely used in the practice today. Pilates moved to New York City in the mid-1920s, and brought with him his reformer machine. As fate would have it, he opened a studio in a space shared with the New York City Ballet.

Soon, the dancers started using the machines, and later Hollywood actors helped propel its use nationwide.

“Today, there are a lot of NFL players and baseball players that use them,” Flanagan said, mentioning Chicago Cubs’ pitcher Jake Arrieta’s frequent use of Pilates reformers.

The machines look similar to a rowing machine, but work differently. The user lays on his or her back and pushes against a bar at the end of the machine to exercise the legs. A network of springs can add resistance and tailor the difficulty of the routine to each user. At the top of the machine, stirrups for the hands can give a workout to the arms.

Primarily, the machines work the body’s core muscles, Flanagan said.

“When most people think of the body’s core, they think of the abs, but really it’s the whole way around,” he said. “Think of the core like a Coke can: The diaphragm is the top of the can, the middle is the abs and the muscles around your back, and the pelvic floor is the bottom.”

There are various routines and ways to use the machines, but the greatest benefit, Flanagan said, is it teaches the user control.

“A lot of exercise accidents happen because there’s almost no control at the end of the motion,” Flanagan said. “When people are lifting weights in a bench press, for example, there’s not a lot of control as people are lowering the weight, and that’s what leads to things like shoulder injuries.”

With Pilates reformers, the springs allow for a more fluid control, particularly at the end range of motion, he said.

The machines can also be modified to give the user a more cardio-heavy workout. Most sessions on a Pilates reformer last about an hour, and can be specific to the user’s fitness needs.

While there aren’t many gyms that offer Pilates reformers in the Golden Isles, their popularity has grown in cities like New York, Miami and Los Angeles, Flanagan noted. He expects to see more cities catch on to the trend.

“They’re getting more and more popular, and I think in the next few years you’ll probably see an explosion of people using them,” he said.