"PUSH! LIFT! KEEP YOUR HEAD DOWN!"

Jane Fonda, in a baby blue leotard and matching leg warmers and with dangling silver earrings, runs to the microphone and verbally pummels about 12,000 pounds of female flesh while Dolly Parton warbles "Great Balls of Fire" on the piped-in stereo.

"This is a KILLER stretch," she shouts. "Abdominals are no sweat for me, but buttocks? Forget it."

More than 100 secretaries, housewives, fitness teachers and professionals have shelled out $48 for two hours of punishment directed by the Drill Sergeant herself. It's another "Workout With Jane Fonda," and the ballroom of the strong-floored Capital Hilton Hotel has been transformed into a sea of jumping, stretching, clapping, thigh-chafing bodies squeezed into rainbow-colored Danskins with Fonda in command.

The same intensity she once focused on anti-war efforts and the nuclear freeze is now spent on the Flab Attack. And Jane Fonda, whose exercise book has been on the bestseller list for 36 weeks, is no softie.

"EXHALE," Fonda screams, her fanny wiggling.

"Oh, Jesus," says 34-year-old Sarah Belew, who has forgotten her "bottoms" and is doing a series of excruciatingly painful knee bends in her underwear and black leg warmers. "If I faint, will you carry me back there?"

It's a cross between an old-time revival and first day at boot camp. Fonda makes Lou Gossett look like a Boy Scout.

"And FLEX, four, five, six, seven, eight. . ."

Fonda lies on her back and starts slapping her stomach. The sea of bodies responds in kind, and the sound of all that fluttering flesh ripples over the room. The sound of 110 stomachs yearning to be taut.

Fonda holds her leg up straight in the air, just like, she points out, "the cover of my book," and the bodies do likewise. Only some do it better than others.

"It can't hurt anyone more than it does me," calls out Fonda in her clipped, authoritative voice. "This is my sixth class in two days!"

The two-hour session is peaking. Groans are heard around the room. Beads of perspiration hang delicately on carefully made-up faces and some of the nicotine-alcohol-candy bar-poisoned bodies have begun to sag. Not unlike the empty Bloomingdale shopping bags in the corner.

"NOW THE BUTTOCKS," Fonda snaps. "Like I always say, if it's gonna be big, it might as well be high, round and hard."

A few titters. Fonda snaps at the man changing the records. "Not that one! La Bamba!" He fumbles for the right record and the second the needle hits the groove, Fonda is on her back, gyrating and twisting her abdomen to the Latin beat. The 110 bodies imitate her. It looks like an audition for a porno flick.

"BRING YOUR KNEES TOGETHER," Fonda calls. "Now, PUSH!"

The bodies push.

"PUSH."

La Bamba is grinding out the rhythm. Trini Lopez would be proud.

"PUSH, PUSH, PUSH."

A heavy-set woman with a halo of dark curls and an official Jane Fonda Workout leotard (sold at a table in the corner for $30 in dusty gray or blush pink), swings her leg around professionally and smiles in Fonda's direction.

"Do you believe that's the body of a 45-year-old?" she pants. She says she is Minette, from Los Angeles, and she is traveling with Fonda, helping the two-time Academy Award winner schedule the book promotion exercise sessions. Is Minette an exercise teacher?

"Hell no," she puffs. "I just have a weight problem."

Fonda is on the small stage, twisting and turning her body. "She loves this stretch," Minette confides.

Over in the corner, Mimi Sokol, 61, stands watching the group grope. "I'm thrilled with it," she says. "I wish I had known about this. I just came down to pick up my hubby. I do aerobics, you know. And I think she's just cute as a button."

Sokol is wearing civilian clothes -- a black skirt and high heels. "I got angry with her over Vietnam, but I like what she's doing now for her body and the respect she has for herself as a woman. I admire that."

Over at the sales table, Rochelle Yowell, 37, is looking over the merchandise. There's the Jane Fonda Workout sweatshirt ($14), the Jane Fonda Workout Sweatpants ($14), Jane Fonda's Workout Book ($17.95), Jane Fonda's Workout Record ($12.98) and Jane Fonda's Workout Video Tape ($60).

"I bought the record," Yowell says. Yesterday was her birthday. The Jane Fonda Workout session was a birthday present to herself.

The class is gearing up for another exercise. This one involves stretching both arms over the head and swinging to the left and right.

"We're gonna do 60 to the right and 60 to the left," Fonda says.

Audible groans.

"You won't believe how fast it goes."

Fonda jumps from the stage and inspects the troops, stopping beside one woman to admonish her form. ("DON'T bend your knees. That's better"), and giving the women and one man (Bill Cash, 30-year-old executive with AT&T who arrived with his briefcase and short shorts) a close-up look at the Jane Fonda Worked-Out Body.

"Do you believe it?" says one housewife in shocking pink leotard and six rings on one finger. "You don't feel so bad about getting old when you look at her."

After a few minutes of a "cool down" period, something akin to water ballet on wall-to-wall carpet, Fonda sits up, takes a swig from a bottle of Evian water and answers questions on diurectics (she drinks two quarts of water a day), vitamins, diets, her weight ("I don't know how much I weigh"), shin splints, whether the bikini scene in "On Golden Pond" was done with special effects, as claimed in a recent Doonesbury cartoon ("It was cold as holy hell in that water. I wish it had been done with special effects") and sunbathing. She doesn't. "You pay all winter. First with skin cancer, and second with wrinkles."

The women line up to have Jane Fonda autograph the Jane Fonda Workout Books they clutch under their arms. It has been, most of them say, an exhilarating experience. Well worth the $48. It will motivate them, they say.

But one woman isn't so sure. She puts on her coat and whispers in Fonda's direction, "You know, she has a thick neck."