"SOME PIECES are tooth pullers, others just belch out full blown," Alison Chase remarked recently as she discussed the creative process of the now-venerable Pilobolus Dance Theatre, of which she is a founding member. The unorthodox but ever-popular dance collective is finishing a week of performances Friday and Saturday at the Kennedy Center Eisenhower Theater with a program spanning the troupe's three decades of back-bending, rubber-limbed choreography that demands the strength and flexibility of Olympic gymnasts, the daredevilry of extreme sports fanatics and the liquid grace of ice skating champions.

The program's earliest work, "Walklyndon," was created in 1971 by the four original Pilobolans -- Robby Barnett, Lee Harris, Moses Pendleton and Jonathan Wolken -- all Dartmouth College students who had wandered into Chase's modern dance class one semester and left with the spores of a dance company. Thirty-one years ago when that quartet of young men showed up in Chase's class with not a stitch of dance experience, but plenty of creativity, she knew standard methods would be moot. "I realized that I couldn't teach them as I would teach dancers," she explained, "so I started teaching them improvisation and choreography instead.

"They had never seen modern dance," she recalled, "so they had no preset expectations . . . they were completely fresh." Chase introduced them to contact improvisation -- a form where partners and small groups give and take their weight by leaning, carrying and lifting one another in unscripted, gamelike fashion. What emerged was a completely collaborative team of movers -- most still hadn't taken an official dance class -- that became the talk of the dance world for its uninhibited and often humorous approach. Wolken contributed the name Pilobolus -- a sun-loving fungus found in barnyards and pastures -- and the rest has been dance history.

Today, though the founders no longer perform, three of them still choreograph, singly and in teams for Pilobolus and other companies. Chase joined her students in 1973 and she and other early company members continue to create new works along with six current company dancers. "You can look at the dancers on stage and see 32 years of dancers' experience," Chase says, adding that the current generation of Pilobolans is far stronger and more adept than the original crew. "Each generation comes and adds another layer on to what the previous one had done."

While the company is based in a tiny town in northwestern Connecticut, Chase lives on the coast of Maine with her husband and three teenage children. For the past few years she has chosen to choreograph solo: "It's currently what I've needed to do. It's not that I won't go back to collaborating with the team, but I find I have a closer relationship with the dancers through this process."

Chase collaborated on her latest work, "Ben's Admonition," with dancers Ras Mikey C and Matt Kent in true experimental fashion. The title, selected from solicited submissions earlier this year during performances in Philadelphia, refers to Benjamin Franklin's still-relevant admonition to the fractious Continental Congress of 1775. Rigged from the rafters, the two men hang from their heels, bare-chested and freed from the floor. "It's all upper torso hydraulics," Chase explained. "That whole illusion of float . . . it's all in the upper torso." At first, she added, the dancers couldn't get through the entire dance because it demanded such tremendous physical strength. But now, after months of rehearsals and performances, she says, "They're cut like diamonds."

PILOBOLUS DANCE THEATRE -- Friday and Saturday, Kennedy Center Eisenhower Theatre. 202-467-4600.

Pilobolus's back-bending acrobatics come to the Kennedy Center.