You might know it as a Swiss ball, a balance ball, a physio ball, or even just an exercise or fitness ball. But this simple round gadget makes a great addition to a home workout, especially for people with rheumatoid arthritis (RA).

Stability balls actually got their start among physical therapists (PTs) in Europe (hence the “Swiss ball” nickname), and when they first found use in the United States in the 1980s, they were typically located in physical therapy centers. Only later did the balls find a place in gyms, yoga and Pilates studios, and people’s homes. Stability balls range in size, but they typically measure two to three feet across and are filled with air.

What Makes a Fitness Ball Helpful for People With RA?

Because they’re like very strong balloons, the balls create a slightly unstable surface, which causes you to engage more muscles when you work out. “One of the reasons the ball is especially good for people with RA is you strengthen the small muscles that help stabilize the joints, just by trying to keep yourself balanced,” says Scott Haak, a physical therapist at the Mayo Clinic in Jacksonville, Florida.

Lightweight and versatile, fitness balls can be a great start to a home gym. Not much research has been done on the balls, especially among nonathletes, but a small study published in August 2013 in the Journal of Strength and Conditioning Research found that three months of exercising on a ball improves posture, gait, and balance in older people.

Work With a Physical Therapist

As with any exercise program, consult with your physician before starting. It’s also a good idea to work with a physical therapist at first. The PT will assess your physical conditioning, balance, and joint damage and help you come up with a customized exercise program. A physician will refer you to a PT, and there’s a good chance some PT sessions will be covered by an insurance company.

How Steady Are You?

You and your PT will need to determine whether your muscles give you enough balance for sitting on a stability ball. In the assessment, you sit in the center of the ball and slightly lift one foot off the floor. If you can’t stay stable or are too nervous about falling, skip exercises that involve this position. You can still do moves where you lie on your abdomen (see below), since this position requires less balance.

Where to Find a Stability Ball

Stability balls are not expensive. Most sold by Amazon, Dick’s Sporting Goods and Target, for example, range from $20 to $30. Many sporting goods stores and discount department stores sell these balls. The size you need depends on your height, and the balls are labeled accordingly; a midsize, 25.6 inch (65 cm) ball is good for anyone from 5’4” to 5’11”. When you’re sitting on the ball, your hips should be at about the same level as your knees.

You Might Need a Pump, Too

Stores typically sell balls that are deflated, so if you don’t already have an electric pump(such as for an air mattress) or a bicycle pump, you may want to borrow or buy one, since the small, handheld pump that comes with the balls is not very effective, and can be hard to use when you have RA. You’ll have to periodically top off the air to keep the ball firm.

How to Get Started Exercising With a Swiss Ball

Wear comfortable or workout clothing; you can wear sneakers or exercise in your bare feet, whichever you prefer.

Set up the ball on carpeted flooring, a no-slip rug, or a yoga mat. Another location Haak suggests is a hallway or a doorway, so you’ll be near a wall you can use for support until you feel secure.

Best Ball Positions for Beginners

Stability balls are popular because they are so versatile. You can use them for a wide variety of exercises and a number of different positions.

Position 1: Sit on the Ball

“Getting on and off the ball is exercise in itself,” because of how much you have to engage your abdomen, or core, says Genie Lieberman, the director of the physical rehabilitation institute at the Boca Raton Regional Hospital in South Florida.

To do this, stand with the ball on the floor slightly behind your legs, with your feet hip distance apart. Tighten your abdominal muscles and begin to bend your knees. Reach one hand to touch the top of the ball to stabilize it as you sit. Keep your bottom firmly in the center of the ball, with your feet flat on the floor. This position is good for doing basic arm and hand exercises (wrist circles, biceps curls). It’s also good for working the core.

Beginner Move:Leg Marches

Sit up straight and tighten your abdomen. Lift your left foot 2 to 3 inches. Hold for a few seconds, then return your foot to the floor. Switch sides. Repeat 10 times.

To dismount, tighten your abdomen as you place your hands on the ball next to your hips and pull up into a standing position.

Position 2: Chest on the Ball

“I like patients to do shoulder movements while lying on the ball,” Haak says. “It’s better than being on the floor because you have more range of motion in your arms,” he says. Try this shoulder-blade tug, Haak suggests, to strengthen the muscles that keep posture aligned.

Beginner Move: Shoulder-Blade Tug

Facing the ball, bend and bring your knees to the floor. Place your hands on the ball as you roll forward, slowly, so your chest moves forward as your knees lift off the floor. Stop when your abdomen and lower chest are on the ball. Keep your feet on the floor.

Remove your hands. Slide your arms toward your hips, with your palms facing down, and pull your shoulder blades toward each other. Hold for a few seconds and release.

Repeat 4–5 times.

To dismount, place your hands firmly on the ball, push your hips back over your feet, and stand.

Position 3: Back on the Ball

This is a good position to work core muscles, since you have more range of motion than when you lie on the floor. To begin, sit on the ball. (See Position No. 1.) Place your hands on the ball at your hips and lean back slowly. When you’re steady, walk your feet forward until your back rests on the ball. Keeping your feet on the floor, push down on your heels to keep your hips up; use your ab muscles to keep your head and torso in line.

Beginner Move: Leg Raises

With your back on the ball, tighten your abs and raise one foot 2 to 3 inches off the floor. (Go slightly higher if you have good balance.) Hold for a few seconds, lower your foot, and switch sides. Repeat 10 times.

To dismount, return to a seated position like this: Tighten your core, tuck your chin toward your chest, and raise your torso as you walk your feet toward the ball. Then stand (see dismount instructions).