Let's Get Physical

By that time, the boomers had transformed the rest of the fitness world into a multibillion-dollar industry. The actress Jane Fonda had become the fitness goddess Jane Fonda, taking the relatively little-known concept of aerobics (coined in 1968 by an Air Force doc named Kenneth Cooper) and giving small classes to friends starting in 1978. "Jane Fonda's Workout" became one of the best-selling videotapes in history. Three years later the few people still resisting Fonda's cheery aerobics juggernaut could no longer avoid it; it was all over the culture.

It's hard to know what Eisenhower, 25 years later, would have made of Newton-John's hit video for "Physical," which came out in 1981. An ode to casual sex that posed as an exhortation to exercise—everyone sing along, Let me hear your body talk!—it would go on to become the biggest chart topper of its decade, thanks in no small part to the video of Newton-John cavorting with Speedo-wearing, Schwarzenegger-esque studs in what looked like a cross between a gym and a porno set. Never mind that at the end of the video, the guys ran off holding hands with each other; the song launched a million boomer fantasies of all sexual persuasions, did wonders for sales of terry-cloth headbands and turned working out into the hottest form of foreplay.

After that came Simmons, who briefly threatened to cancel out all the sexing-up fitness that Fonda and Newton-John had done, but brought in hundreds of thousands of new workout enthusiasts in the process. Then there was the ThighMaster. Somers didn't invent it (the creator was one Joshua Reynolds, father of another device of dubious effectiveness, the mood ring), but she did for it what Fonda did for leg lifts. Then came Bowflex, and NordicTrack, and kickboxing, and yoga, and Pilates.

Which brings us to today's Aerobic Striptease, a workout routine in which participants take off both unwanted pounds and their clothes. Think it sounds risqué? It's no more so than the "Physical" video. You can now see Aerobic Striptease on display in suburban boomer households across the country. Some housewives have installed poles in their living rooms. It has its own Newton-John in the form of Carmen Electra, whose workout videos are top sellers. The more things change, et cetera.

Of course, one important thing really has changed. The people doing the exercising are still happy to strip and kick and grapevine and do the downward-facing dog, but their arms and legs don't always comply. Their muscles are aching and their knees are blown out. Their bodies are still talking—but what they're saying these days is "ouch." That, more than anything else, is what's driving the boomers' latest fitness fad.

At 50 or older, boomers aren't always happy to discover they can't run as fast, leap as far or lift as much as they used to, says Marilyn Moffat, a physical therapist and the author of the new book "Age-Defying Fitness." "I think sometimes they can have a delusional sense of what's happened to their bodies over the last 40 years," she says. "Maybe it's that Me Generation thing, the feeling that 'I can do whatever I feel like doing, and I can do it whenever I want to do it'."