Dancing for 12 hours does certain things to the body and to the mind. You discover muscles you never knew existed and your mind turns into oatmeal. But, as we found out last Saturday, it is really not that hard, provided you don't stop and don't think too much.

At a little after 1 p.m. Saturday, couple #1305 joins more than 100 dancers on the floor of the Palmer Dixon Tennis Courts, anxious to begin at this ridiculously early hour.

As we scout for a good spot from where to begin, various marathon organizers give the obligatory opening remarks, lauding the marathon's charitable cause--the Jefferson Park housing project in Cambridge which will receive the funds we raise--and offering encouragement. Currier House Master Dudley Herschbach estimates that 12 hours of dancing steps totals 13 miles of walking.

The dancers, however, are getting restless. We are still marathon innocents, and are actually anxious to end the speeches and start the music. And at last, once children from Jefferson Park have performed a choreographed dance to the theme from Fame, the disco bacchanalia begins.

From the first song ("Dance, Dance, Dance"), bodies swirl, muscles flex, dancers groove, and sweat oozes from would-be John Travoltas. The participants, mostly couples, are attired in everything from mini-skirts and shorts to more theatrical fancy dress wear.

A little bit later, Governor Michael S. Dukakis enters with a small entourage and the dancers take a brief respite to gather around the newly elected chief executive. Were it not for the Harvard and Currier House banners hanging from the wall, a casual observer might have mistaken the Duke for Dick Clark and the dancers for participants on American Bandstand. After the blessing, Dukakis exits and the Clash's "Rock the Casbah" fills the cavernous building.

After 45 minutes, energy is still high and we are loosening up. Enthusiastic dancers engage various bystanders including President Horner, in the terpsichorian revelry. #284, who said he came alone, dances around the periphery, Walkman earphones firmly in place. "I'm alone, so the slow songs are a bit of a problem. I've got Michael Jackson on the Walkman so I can keep on grooving," he says when questioned later as he dances on the tennis umpire's chair left in the middle of the dance floor.

The Jefferson Park kids, observing the lack of talent of some of the couples, put on a small exhibition for couple #855, who appear sufficiently grateful to their diminutive coaches. Others pass the time by reading the newspaper to the strains of "Shake It Baby."

The first break comes at 2:50 and the first of a series of exoduses to the refreshment tables begins. The dancers are milling around--some are sitting, but a surprising number are still on their feet. Our first intersession also brings two lucky winners door prizes: a gift certificate for Ruggles Pizza (won by #689) and two Sack Theater passes (won by #22). But all too soon the DJs start spinning their records and, hurriedly gulping one more cup of diet soda, we bounce back to the floor.

At 3:45, #1205, Jenny from Lowell House, and #061, Ben from South House, introduce themselves. #1205 attired in an Annie t-shirt and a black mini-skirt says all her roommates are participating in the revelry as #061, decked in jeans and a black t-shirt, spins her violently in a circle. They soon move along, engaging in mock combat.

Only another two hours or so until dinner, and after that, we're into the home stretch. All the same, it is a bit tougher than before.

New Order's "Temptation" takes us into a line of quasi-bunny-hoppers, boogieing like a mammoth, 400-legged caterpillar. Then Michael Jackson's "Billie Jean" tells the guys not to go around breaking young girls' hearts.

"That's me, man," says #937, gesticulating to reinforce his claim to lady-killerdom.

Visions of mortality come just before the third break. The physically demanding "Rock Lobster" leaves two dancers down for more than a minute, while the rest pogo wildly, contributing to Palmer Dixon's growing, resemblance to a locker room.

By 5 p.m. we are back dancing and the first 10 minutes are easy, but 20 minutes later it takes Elvis and "Jailhouse Rock" to restore our energy.