A majority of Americans say they "exercise strongly" every day, suggesting that physical fitness has broad, and still growing, appeal for adults of all ages, according to a recent Washington Post-ABC News public opinion poll.

"In the past 20 years the number of American adults who exercise regularly has continued to increase," said C. Carson Conrad, executive director of the President's Council on Physical Fitness and Sports, when asked to comment on the poll. He cited "growing involvement" by women and the elderly. "It hasn't peaked," he said.

The new poll found that more men exercised regularly than women, but women may be catching up, particularly younger women. About 6 in 10 adult men said they exercised daily, compared to 46 percent of women. And while the percentage of Americans exercising decreases with age, a surprising 4 out of 10 adults over 60 said they exercised daily, compared to two-thirds of those 18 to 30 years old.

The poll asked a representative sample of adults 18 and over whether they "exercise strongly for a total of 20 minutes or so a day." Exercising strongly was described as "any activity that causes your breathing and heartbeat to increase rapidly and strongly," a definition commonly used for so-called "aerobic" sports such as swimming, jogging, bicycling and walking.

Of the 1,505 people interviewed, 53 percent said they exercised daily, while 46 percent said they did not and 1 percent had no opinion. Another 26 percent said they exercised every few days and only 21 percent of the sample said they exercised once a week or less.

Follow-up interviews showed that the question was broadly interpreted.

"The work that I do around here keeps me more fit than most people," said a New Mexico appliance salesman who estimated that he moved a ton of machinery each week.

"I work out at a health spa and do a whole lot of walking," said a 45-year-old Gary, Indiana man, who began working out a few years ago to control his weight.

A southern California woman who said she walks two miles a day, five times a week was not deterred by a recent heart bypass operation and credited exercise with helping her to "recoup much faster from surgery."

Gallup polls have shown a jump in recreational exercise on a regular basis from one-fourth of the population in 1961 to nearly one-half 20 years later. A recent A.C. Nielson survey found that swimming topped the list, seconded by bicycling.

Medical experts believe that regular exercise may help protect against life-threatening diseases, while making participants feel better in the process. In the new poll, those who said they exercised daily were more likely to view their health as "excellent" and were less likely to call themselves overweight.

Many of those surveyed also recognized that they should exercise regularly, even if they do not. "I don't think it's good to be as sedentary as I am," said a former physical education teacher now working as a clerk. "I could be in much better shape," said a 35-year-old Danbury, Conn., personnel coordinator. "When I get up to dance, I really feel it," she said. But one poll participant was unrepentant about his sedentary lifestyle. "I don't need it and I don't have the time" said a male Idaho executive.

Exercise was only one component of a Washington Post-ABC News telephone poll on health from Sept. 14 to 19. It also found:

* Ninety percent of those surveyed considered themselves "basically healthy." Forty percent rated their health as "excellent" compared to others their age, while 53 percent said it was "good." Only 4 percent rated themselves as "not so good" and 3 percent "poor."

* The most feared disease was cancer, which was cited by 84 percent of those surveyed, as compared to 30 percent for heart disease.

* Three out of four said they had once had regular measles and chicken pox, while two-thirds had had the mumps. These childhood diseases are now declining dramatically among children.

* Eighty-six percent said they had had the flu, nearly half were bothered by cold sores or fever blisters, one-third had hay fever or similiar allergies, one-fourth reported arthritis, and nearly one-fourth had had a urinary infection.

* Eight percent had serious trouble seeing and another 22 percent minor vision problems. Two-thirds of them said they wore glasses or contact lenses. Nearly one-fifth said they had minor or serious trouble hearing and most use hearing aids.