Palm Desert, Calif. ? A more gentle form of yoga is catching on in some retirement communities.

The yoga mat is replaced by the chair. Sometimes two.

Instructor Lakshmi Voelker-Binder says her students can duplicate any yoga pose typically done on the floor, but it’s easier on those less limber muscles.

During a recent one-hour session, she taught her comfortably supported participants to stretch by holding modified versions of traditional yoga poses. The normally upright forward bend, for example, entailed sitting in one chair and positioning both legs on a facing chair, the hands reaching for the second chair’s arms.

“The only thing I won’t ask you to do is headstands,” Voelker-Binder joked to the group of six women ranging in age from 50s to late 70s. They were gathered in a dimly lit ballroom at the Joslyn Senior Center near Palm Springs.

An estimated 13.4 million Americans practice yoga or other mind-body exercises such as tai chi, according to a 2003 survey by the Sporting Goods Manufacturers Assn. Of those, an estimated 1.6 million were 55 or older.

Those numbers are expected to rise, said spokesman Mike May, as senior citizens join health clubs and senior centers offer more exercise programs.

A self-described hippie who felt “misplaced in New York,” Voelker-Binder moved to Palm Springs in 1989, becoming one of four yoga instructors in the desert city east of Los Angeles. Today, the lean and lithe 55-year-old says there are at least six yoga studios in the area but she teaches the only chair yoga class in town.

The older students say chair yoga increases their strength, flexibility and concentration.

“It keeps me motivated,” said Edie Wallace, a 79-year-old in jeans who switched smoothly between poses.

Yoga instructor Lakshmi Voelker-Binder, right, leads a chair yoga class Jan. 20 at the Joslyn Senior Center in Palm Desert, Calif. An estimated 13.4 million Americans practiced yoga or other mind-body exercises in 2003, according to a survey by the Sporting Goods Manufacturers Assn. Of those, an estimated 1.6 million were 55 or older.

“It helps me want to go further and do more,” Wallace said. “Walk that extra half-hour.”

Nearby, a new student said it was more challenging than she expected.

“I noticed some lopsidedness that I have,” said Susan Evans, 56, who had gone to mat yoga classes for about 18 months. “Plus you have to really balance yourself on the chair, or else you end up slipping.”

Voelker-Binder discovered chair yoga in the late 1980s when she was teaching a mat class and one of her students, Candace Terry, developed rheumatoid arthritis. Terry, who was in her 30s when they met, said her arthritis was so severe she had difficulty dressing herself or opening a car door, much less doing form poses on her hands and knees.

Yoga students Nancy Stock, 66, foreground, and Betty Ann Husebye, 74, right participate in a chair yoga class, Jan. 20 at the Joslyn Senior Center in Palm Desert, Calif. Older students say chair yoga helps increase their strength, flexibility and concentration.

“Lakshmi understood my predicament,” said Terry, now 53. “It’s a gentle way of teaching people to experience it as best as they can, which is very encouraging.”

Terry said she saw gradual improvements in her health as she practiced chair yoga daily for about five years after being diagnosed with arthritis.

“I feel that between yoga, good nutrition and other things I’ve done in my life, I’ve beat the odds compared with many people stricken with the disease,” she said.

Peggy Cappy, an instructor who created the video “Yoga For the Rest of Us,” which includes some chair poses, offers the chair option at her yoga classes in Peterborough, N.H., to help students ease into more strenuous poses. It also helps them gradually build muscles and joints until they’re strong enough to practice on a mat, said Cappy.

“The chair is there for safety,” she said. “As a result, people are willing to try things because they know they’re not going to be hurt.”