Nothing Retiring about Retirement. Retirement complexes can help older people stay in the swing of things. But activity alone can't replace the need to feel useful.

AT Wynmoor Village, a campus-like condominium complex where most of the 7,700 residents are of retirement age, ``activity'' is the byword. It flutters in conversations among residents and in Wynmoor's sales literature like a flag on a ship's mast.

But ``activity'' is more than just talk, as a senior-citizen dance troupe here proves.

At the recreation center, two dozen women in black leotards and two men in black slacks and black T-shirts end one number, and grab top hats and canes to practice the next. All are in their 60s or 70s, except two women, known as ``the babies,'' in their 50s.

Every Monday from 10:30 a.m. to 3:30 p.m., the troupe follows the nearly nonstop example of Gertrude Weinberg, a retirement-age Wynmoor resident who was a professional dance teacher for more than 50 years.

``Faster,'' she shouts. Then she stops them abruptly with a ``No, no, noooh'' to make a correction. Moments later the troupe is in full swing again, dancing and singing the lyrics to Cole Porter's ``Another Op'nin, Another Show.''

``It's exuberating. It keeps you going,'' says dancer Selma Shear. ``Retirees should keep busy.'' Boredom is a person's ``own fault,'' she adds. ``If you've got a good attitude, nothing can get you down.''

The troupe's annual performances here are big hits. But a five-hour rehearsal every week (or, as opening night draws near, every day) is not for everyone. Other activities at Wynmoor include educational classes of all sorts -- swimming-exercise, pottery, sculpture, movies, card playing.

The number of retirement communities -- condominiums, houses, town houses, apartments -- is growing in the United States, says Daniel Quirk, executive director of the National Association of State Units on Aging. Most residents of such communities are in the upper-middle-income and upper-income levels.

But for people who can't afford this option, the choices are fewer -- and the pace of life can be slower.

In the southern part of Miami Beach, for example, chairs on the porches of modestly priced hotels are usually filled with the elderly. The people spend much of their time sitting quietly, talking with other hotel guests, or shopping in nearby stores. Many cook in their kitchen-equipped rooms.

The contrast with the bustle at Wynmoor Village is striking, but, even here, it's evident that activity alone is not enough to satisfy.

``Most of them [residents] are not happy,'' says Florence Schlussel, a resident of the Wynmoor community, located about a half hour's drive from Fort Lauderdale. ``They run from one thing to another. They realize they have no purpose in life. They all miss their children.''

Just doing things is not enough, she says. ``We see people flitting from one thing to another. The happiest ones are giving of themselves. The best way to retire is by keeping healthy, happy, and useful.''

Vita Ostrander of Atlanta, national president of the American Association of Retired Persons (AARP), agrees that usefulness is essential to happiness.

``If the people feel they're being useful and needed and wanted, you can rest assured they're happy,'' she says.

``Bridge, shuffleboard, and ceramics'' are not enough for many people, she adds. In these, ``there's no purpose other than self-gratification.''

Mrs. Ostrander says some retirement homes have so many activities that they become ``playpens.'' With everything focused inward, residents can become isolated from the community, something she opposes.

Indeed, condominium complexes for older Americans can be artificial worlds of sorts, with conditions that suit the residents. At Wynmoor, for example, no children are allowed except as visitors. Residents must be 42 or older. People who live here describe the Wynmoor crowd as upper-middle-income to upper-income people. And the community is what resident Emanuel Reiser calls a ``white enclave.''

Volunteer work is one way older Americans can retain a sense of usefulness in their communities. Many people who want to volunteer, however, do not know how to go about it, and their communities do not ask for their help, says Mrs. Ostrander, who is beyond retirement age herself and serves without pay as AARP president.

Of people age 65 and over who are not now volunteering in some activity, about 10 percent would like to, according to surveys by the National Council on Aging.

New opportunities appear to be opening for older Americans to serve their communities, say several experts on aging.

A new AARP-sponsored program in Fort Meyers, Fla., enlists older Americans as volunteers to help other elderly people weatherize their homes. Another AARP program recruits older Americans to care for handicapped children at home, giving the parents a few hours' respite.

At Wynmoor, some residents serve in local hospitals; others are teachers' aides at a neighboring high school.

Among the people interviewed here, there is a strong conviction that enjoyable activity helps people stay young. Retired dentist Milton Haveson, finishing work for the day on his sculpture of a Chinese girl, says the key to not feeling old is ``don't think old.''

And to Mrs. Weinberg, ``this kind of living for retirees is super. Past 70 is young here.'' When not teaching dance, she takes art lessons, plays golf, and has studied current events at a nearby community college.

But it's more than activity for activity's sake that Mrs. Weinberg enjoys. She likes sharing her skill in dance, bringing out the best in others, and helping them capture the joy of performing. She loves it -- and it shows. Her face glows and her eyes are bright as she glides through the steps, spinning out choreography that is based on half a century of experience.

Arthur Fleming, former US commissioner on aging under President Nixon and former secretary of Health, Education, and Welfare under President Eisenhower, says:

``There's no doubt at all many older persons are very anxious to continue to be involved in life. Noninvolvement leads to mental, physcial, and spiritual deterioration.''

And he adds: ``The happiest among the older persons are those who seek and find opportunity to be of help to others.''

Next: A visit to a senior-citizen center in Milton, Fla.