Betty Switkes, 78, who developed a series of exercise programs for the elderly that could be performed while sitting, died Aug. 3 at Himalayan Elder Care, an assisted living facility in Silver Spring. She had dementia.

After raising her family, Mrs. Switkes worked as an assistant to the director of the National Institute on Aging and began to think of ways to combine her interests in fitness and the elderly. She had been entranced by gymnastics while growing up in Washington and was a devotee of modern dance, exercise and yoga.

In 1979, after studying anatomy and physiology, she devised an exercise program for the elderly and led classes at senior centers. Mrs. Switkes knew that traditional workout routines, in which exercises are performed upright or on the floor, often were difficult for older people, particularly those with illnesses or disabilities. She came up with a series of workouts that eliminated the risk of falling and the need to climb up off the floor.

By 1984, she had begun to market her program, "Armchair Fitness: An Aerobic Workout for People of All Ages," in book and video formats. With exercises called "turkey wings," "nose circles" and a sedentary version of the cakewalk, Mrs. Switkes inspired a newfound interest in aerobics among an older generation.

"You don't have to go to a fancy gym or twist yourself into a pretzel to get a good aerobic workout," she said.

Mrs. Switkes wrote other books ("Senior-cize: Exercises and Dances in a Chair" and "Armchair Fitness: Gentle Exercise") and continued to make exercise videos into the late 1990s. She appeared on the "Today" show and "Entertainment Tonight," enthusiastically putting television hosts and audience members through her low-impact workouts. She taught her exercises on an around-the-world cruise of the Queen Elizabeth 2.

A review of one of Mrs. Switkes's videos in People magazine in 1988 described her as a "trim but shrill instructor, with a voice that seems to bounce off the rafters." It complained that the music on the video sounded "like a bad Vegas lounge act" but concluded, "Don't think you won't get a good workout."

Mrs. Switkes told The Washington Post in 1996: "There are an amazing number of people who just don't like to get on the floor and exercise but still want to be healthier and work out. You can raise your heart rate no matter what your age, sitting in a chair if you know how to do it."

Betty Cooper Switkes was born in Baltimore and grew up in Washington. She graduated from Roosevelt High School and, in 1948, from George Washington University.

She was an administrative assistant at a women's health clinic in Washington in the mid-1970s and, from 1977 to 1981, worked at the National Institute on Aging. For almost 20 years, she and her husband, Joseph, spent winters in California, where Mrs. Switkes promoted her exercise routines to the elderly.

After living in the District, Silver Spring and Wheaton, she settled in Chevy Chase in 1967. She was active in the League of Women Voters and was a member of Temple Emanuel in Kensington.

Survivors include her husband of 55 years, Joseph N. Switkes of Chevy Chase; three children, Ellen Switkes of Sherman Oaks, Calif., Harvey Switkes of Annapolis and Nancy Switkes Bell of Rockville; and two granddaughters.