Editor's Note: This corrects an earlier version.

COSTA MESA — When patients are zipped into the air-tight Alter G Anti-Gravity Treadmill from the waist-down, it feels like walking on the moon, said Chad Jarrett, co-owner of Jarrett Orthopaedic Rehabilitation in Costa Mesa.

The rehabilitation center's recently acquired Alter G anti-gravity treadmill can help physical therapy patients take a giant leap toward total recovery, because movements on the machine are less of a shock to the legs' joints, said Jarrett, a physical therapist.

The Alter G forms an airtight seal around a patient's waist and uses air pressure to slightly lift the user off the treadmill, minimizing the impact of walking or running.

The result is diminished stress to a patient's body, which means a quicker recovery time between exercise and physical therapy sessions, said Jarrett, who uses the machine in between training for annual triathlons.

"Your body is unweighted," Jarrett said about the NASA-designed machine, which can temporarily remove up to 80% of the weight from a patient's lower body. "There is so much less stress to the back, knees and ankles."

Some patients, such as Sarah Kull, 82, who has Parkinson's, use the anti-gravity treadmill as an alternative to aquatic therapy.

While the aquatic therapy was helpful, she said the anti-gravity treadmill is "more fun."

"I feel more stable, and I have something to look forward to," Kull said.

Kull began using the machine several months ago to exercise her legs, which have become unstable and unable to support her weight due to Parkinson's.

"She's benefiting from being able to have mild cardio exercise that would not have otherwise been unavailable to her," said physical therapist Jasmene Jarrett, who opened the center with her husband in 2002. "It wouldn't be safe for her to walk on her own, unless she has someone holding her up."

However, the anti-gravity treadmill isn't just for physical therapy patients. The low-impact exercise is beneficial to athletes doing high-intensity training who need to minimize the wear and tear on their bodies, such as marathon runners, she said.

The benefits also extend to overweight patients who may have trouble with normal cardio exercise, she said.

While most of the patients are referred to the center by their doctor, any person can buy sessions, beginning at $15 for 30 minutes, to use the Alter G.

County residents will be able to try out the Alter G on March 28 at an open house at the center. Jarrett Orthopaedic Rehabilitation is in Suite 128 at the Back Bay Center, 2651 Irvine Ave.