The huge, white-pillared colonial mansion rests on 14 rolling acres in a Dallas suburb, and parked out front is a spiffy yellow Jaguar. It is easy to imagine the place filled with handsome couples, chatting discreetly while they sip tall drinks.

Surprise. Inside are scores of wheezing, paunchy, middle-aged men in soggy sweatsuits who have come to be whipped into shape by the Jaguar's owner, Dr. Kenneth Cooper. This is his world-famous—if not universally admired—Aerobics Center. Cooper, 44, founded it three years ago to continue the research that led to his 1968 book, Aerobics, an astounding bestseller.

Now more than 6,000 clients—many of them high-level corporate executives—come to Cooper's center during a year. For $285, most are given exhaustive physicals that concentrate on evaluating the circulatory and respiratory systems. There are also three-day workshops that cost $200, and a $450 annual membership that includes individually designed exercise programs. "We are not a care center for the sick," Cooper says. "We are devoted to preventive medicine."

Cooper was an Air Force doctor when his observations of even the relatively healthy military personnel he treated convinced him that most Americans are dangerously out of shape. A former Oklahoma high school champion miler (his best time was 4:31), he had eaten himself chubby during medical school before going on a reconditioning program. So he took his own experience, combined with evidence from his practice, and devised a program he named aerobics ("aerobic" refers to the life-sustaining qualities of oxygen).

The theory is that the heart, lungs and blood-carrying system are strengthened by strenuous exercise, and that running, fast walking, swimming and bicycling are the best. In Dallas, perhaps partly out of envy for Cooper's financial success, some doctors find "a lot of hokum" in the aerobics program. "Exercise has not really been proven a deterrent to a heart attack," said one cardiologist, adding, "but it sure makes you feel better."

Criticism of Cooper began with his book. Doctors feared he might be endangering the health of sedentary readers with his recommended test of aerobic health—trying to run a mile in less than 12 minutes. Cooper revised later editions of the book to include a program of build-up exercises.

While some physicians still grumble that he is mongering publicity and money with unproven theories, Dr. Lawrence Lamb, formerly a top Air Force cardiologist (under whom Cooper was training as a resident), says: "In the course of being beat over the head by a lot of heart specialists, he changed parts of his approach and overall he's done a lot more good than harm."

Cooper retired from the Air Force after 13 years' service in 1970. When the the Tyler Corporation, a Dallas-based transport and engineering conglomerate, offered financial backing for the aerobics center, Cooper accepted, showing his gratitude in an unusual way. He named his new son Tyler and in 1972 instituted the Tyler Cup race, an annual and prestigious two-mile run for corporate executives. (This year's race produced the first cardiac emergency in more than 450,000 jogging miles at the Aerobics Center. The victim, an out-of-shape substitute for another company official, was revived by Cooper and his medical staff. His collapse was attributed to overexertion, and he recovered uneventfully.)

Cooper himself is now primarily concerned with compiling the first large-scale study of how exercise affects heart and lung ailments, which he hopes to publish by 1985. Meanwhile, practicing what he preaches, Cooper still jogs three miles a day ("If I stop, I deteriorate"). A devout Baptist, Cooper also joined Billy Graham on a crusade last year in Brazil and was warmly received by a crowd of 248,000 in Rio de Janeiro, where his book was a big success. The reception may not have been entirely due to his piety. In Brazil, they call jogging "The Cooper."