RALEIGH, N.C. -- Exercise is recommended for burning calories, but some people complain just walking puts too much pressure on their joints.

They may not realize they could exercise in a weightless environment -- a swimming pool, reported WRAL-TV in Raleigh.

Many swimmers who come to Gypsy Divers Aquatic Center in Raleigh come for fun, but Sally Osisek comes for exercise and therapy after a shoulder replacement.

"When you get to my age and have arthritis, it's the one thing you can do and enjoy," she said.

Aquatic therapist Rosemary Herlong helps Osisek restore full movement in her shoulder by swinging the affected arm underwater. Losing a few pounds would be icing on the cake.

"If I would just lose the weight, it would be so much better on my knee," said Osisek.

Herlong said aquatic exercise can help anyone lose weight.

"One hour of aquatic exercise is the equivalent of two (hours) on land," she said.

"I like that formula because I'm here a hour and a half every time I come," Osisek said.

"It's very deceptive because you've eliminated gravity and you don't feel like you're working hard," Herlong said.

Herlong recommends a mix of swimming and water aerobics to work every muscle group, but many people cannot swim and do not want to learn. Exercise in the water is still possible.

"Many times, you can just be vertical in the water. Your head never has to go under," Herlong said.

Herlong's clients use different flotation devices to keep them upright in deep water, with Herlong by their side. Other flotation devices help leg or arm muscles by resisting the pull of the objects to the water's surface.

Osisek said the exercise is strengthening her joints and toning her body, but so far she hasn't lost much weight.

"I have to stay out of the kitchen to do that," she said.

Most people who take part in aquatic therapy are referred by their doctors. Consult your doctor before beginning any exercise or therapy program.