During World War One, a German man named Joseph Pilates, interned as an "enemy alien" in England, was rigging hospital beds with springs in the name of fitness.

Pilates, founder of the exercise system of the same name, was creating a means for bedridden patients to participate in his fitness regime. By attaching springs to the beds, Pilates gave these patients the ability to work against resistance.

And so the idea for his later equipment designs was born.

Almost 90 years later, I'm lying on a sliding plank, my legs are lost somewhere above my head and my feet are hooked into pulleyed straps.

This is the reformer, one of several pieces of equipment Pilates designed to both aid and challenge participants of his exercise system.

The apparatus is a bed-like frame raised a few inches from the floor. The carriage, a moving surface, is rigged to a series of springs and slides along the frame with resistance. On one end, straps are attached to two pulleyed cords, and on the other, a foot bar is elevated above the machine.

A whole new ballgame

Much like the traditional mat work, reformer classes consist of a series of exercises that work the body to the core. You start with the classic warmup - lateral breathing, pelvic, shoulder and neck placement, and deep abdominal muscle engagement - and then move on to familiar exercises.

But as I'm sliding, pushing, pulling and lifting my way through my reformer class, it's like I've never taken a Pilates class before. A new part of my body shakes with every exercise and I'm inhaling and exhaling with audible force.

What's the reason for my unfamiliar shakiness and exhaustion? It's quite simple: dynamic resistance and a moving surface. The springs that attach the sliding carriage to the reformer's frame, which are added and subtracted throughout the class, make Pilates a whole new adventure.

Beth Evans, the program director of education at STOTT PILATES®, says the reformer allows you to vary the resistance you're working against by adjusting the number of springs connecting the carriage to the frame. During a mat workout, the only resistance is your body weight. This can be manipulated by lifting up various parts of the body, but the reformer is more specific, she says. The dynamic resistance the springs provide also means you have to work that much harder.

"It prompts your muscular contractions to be very smooth, because otherwise, you'd get a jerky movement and you will notice that," she says. "You can also notice the symmetry or asymmetry of your body more on the reformer."

Wendy Johnston, who has been practicing Pilates for two years, started working on the reformer with instructor Christy Wade just under a year ago. Johnston says the reformer was tricky at first.

"It was just a little awkward until you got used to the spring movement and what you can and can't do with the springs," she says. "You have to think about what you're doing more."

"The reformer doesn't lie"

The reformer does something a little sneaky. It takes all those times you cheated during mat work - with our without knowing - and brings it to your attention. Because you're on a moving object that is attached to springs, if you don't do the exercise just right, you're in for a not-so-smooth ride.

"You cheat on the mat a little bit and you don't know," says Wade, the owner of Halifax's Studio In Essence. "And the reformer doesn't lie. It moves or it doesn't move, or it moves really fast. So you have to articulate through your body and be more controlled."

The resistance from the springs also allows you to isolate specific muscle groups. On the mat, where the only resistance is often your own body, exercises like bicep curls and tricep extensions aren't in the workout. But with the straps, you can target small muscle groups in the arms, for example; or with the foot bar, you can work out all parts of the leg.

Evans says the reformer's versatility means the participant is in for a full-body workout.

"You can get into many, many different positions on the reformer," she says. "You can lie supine, you can lie prone, you can sit facing any direction, you can kneel, you can stand, and you can lunge. So with that in mind, you can target any of your muscle groups."

And with all those directions and parts, Pilates on the reformer requires your mind to work just as hard as your body. Not unlike every other form of Pilates, you must focus on your muscles - and concentrate.

"It brings your attention to what you're doing," says Evans. "You can't do it mindlessly."

Anyone can do it

Despite the reformer's complicated nature, both Evans and Wade assure me it's for beginners and experts alike. Anyone can get on the reformer, so long as the participant is appropriately prepared.

Wade says a participant should use the mat to get comfortable with basic Pilates principles, such as breathing and muscle awareness, and then move to the reformer. She says this process could be as simple as attending a private class before moving to the equipment.

"You need to get an idea of where you're breathing and all of that, and then apply that to the reformer," says Wade.

Evans says a participant could start on the reformer if they wanted, provide the class goes through the same awareness that would be done on the mat.

No matter your background, you don't want to completely switch your exercise regime to Pilates on the reformer. It's important to vary your workouts as much as possible so that your body doesn't get used to the same routine.

"For a healthy person who is really doing it for fitness, it's good to have as much variety as possible, in the workouts and on the equipment," says Evans.

With all the other pieces of equipment Joseph Pilates provided for his exercise system, such as fitness circles, weighted balls, barrels, the stability chair, and the Cadillac, variety isn't hard to achieve.

For Wade, equipment such as the reformer, designed to either give support or provide a challenge, opens up to the participant another layer of the Pilates method.

"I think all of the equipment serves its purpose to give you a little extra piece of the puzzle to help you understand."