Slick promotion + snappy tunes + sit-ups = a record-chart first.

When an LP cut by an unknown artist and released by a little-known label begins bulleting its way up the charts—from No. 182 in Billboard to No. 56 in just 10 weeks—something's stirring. Perhaps the sound that will turn back the New Wave? Or is it this year's version of the Bay City Rollers? Well, in Carol Hensel's case what's stirring seems to be the proverbial thin soul inside every fat body. Enough chubbies have shelled out $8.98 to make Carol's Dancersize—seven tracks of middle-of-the-road instrumentals overlaid with her exhortations—the first exercise album to crack the Top 100.

Unlike the choreographed aerobic dancing classes that fitness guru Jacki Sorensen has franchised around the country, Hensel's dancersizes are simple (sit-ups, side-stretches, knee lifts and the like), cheap (the only expense is the album price) and private (they can be performed at home as easily as at a studio). In short, the LP offers little new in the way of exercise routines, but it is a phenomenon of packaging and promotion.

According to Hensel, a 27-year-old dancer and part-time exercise instructor from Ohio, similar albums haven't made the grade "because the music wasn't hip." Dancersize includes instrumental versions of Gloria Gaynor's "I Will Survive," Billy Joel's "Just the Way You Are" and Peter Allen's "I Go to Rio." Hensel's instructions ("Let's warm it up, stretch, arch your back..."), which correspond to a 20-page illustrated booklet that comes with the album, are delivered over the unrelentingly upbeat tunes but never overwhelm them. "I don't shout, 'C'mon ladies!' " she says. "I've never thought of myself as the jock type."

Indeed, fitness buffs may find Dancersize less than challenging. Hensel, who first tried the routines on 500 women at the Cuyahoga Falls, Ohio YWCA, makes no apologies. "I wanted the exercises to be uncomplicated," she says. "I'm like everyone else—basically lazy."

The idea for Dancersize came from Joey Porrello, president of the Cleveland-based Our Gang Entertainment, Inc. He scouted most of Ohio before picking Hensel as his pitchwoman. "We are promoting her the same way we would a rock star," he explains. Rather than buy advertising, Porrello hyped the Vintage Record Co. release through newspaper articles which led to air time on more than 60 radio stations around the country. "I was in the right place at the right time," reckons Carol. "Usually they pick blondes from California for this sort of thing, not brunettes from Ohio."

The youngest of three children born to a gynecologist and a nurse, Carol began music and dance lessons at age 5. She gave them up in high school but resumed dancing when she entered Stephens College in Columbia, Mo. She was teaching dance exercise classes at the University of Akron and a nearby Y when Porrello found her.

At 5'7" and 120 pounds, Hensel has never had a weight problem, but she insists, "It's more important to feel good than to be skinny." She recommends neither health foods nor vitamins ("They are rip-offs"), is a lapsed jogger ("It's boring") and gave up bicycling after a dog nipped at her ankle. Her own exercise regimen: 40-minute workouts three times a week.

Carol, who shares an Akron apartment with her insurance executive brother, Raymond, is starting to work on her second album, due out in late July. By fall she may also have a syndicated Dancersize TV show. In addition, Porrello is lining up a string of endorsements including exercise clothes, spas and even those "rip-off" health foods. "I can be a hypocrite," she smiles. "It depends on how the product is promoted. Really, I'm a cynic."

Hensel's schedule leaves little time for her boyfriend, drummer John Beatty, who she admits is "a little resentful"—he has yet to score a hit record of his own. Carol's only regret, however, is how long it took her to become a public figure. "I wish I was doing this at 20," she says. "I looked a lot better then."