It's a drizzly Sunday afternoon, a time when most people opt for curling up with the paper or catching a few winks. But inside a University of Maryland dance studio, a sense of quiet industry prevails. Five women sit in the corner sewing. Two men stretch long black ribbons across the room to form a huge grid while another rolls newspapers into tubes.

Moments later, all don black, one-piece suits, take their places around the grid and spring to life, hurling their bodies through space, coming together in both harsh and tender physical confrontations.

These are the eight members of Improvisations Unlimited, one of the area's most consistently inventive dance troupes, and the piece they are rehearsing is "Flower Field," by renowned Japanese choreographer Kei Takei. A strenuous dance, it demands not only great strength and endurance, but less tangible qualities: honesty, openness, daring.

Improvisations Unlimited excels at all of them. In residence at the university since 1978, the troupe, under the direction of choreographer and professor Meriam Rosen, performs a great variety of dances both intense and lighthearted by an impressive roster of artists.

The company's raison d'e tre, however, is improvisation -- the act of creating movement on the spot, without fear or inhibition. Each dance performed contains at least one section in which the dancers must make spontaneous choices. In addition, Improvisations Unlimited, which performs tonight and Saturday at 8 in George Washington University's Building K Theater, opens each concert with "Sets," a series of short, unplanned sequences based on verbal cues that Rosen devises in secret.

"Just getting up there and not knowing what you're going to do is scary," says lanky, athletic Heather Walker, a 20-year-old math and dance major. "There is always risk involved. And sometimes I know I've done something that's absolutely gorgeous and I don't even know exactly what I've done."

"Flower Field" has afforded Walker one of her chanciest performing experiences yet. During one of the piece's most memorable passages, she must hurl herself repeatedly onto fellow dancer Bradley Ehrlich's back. The fact that he is running doesn't make things easy.

"For a long time, I felt like I was being beaten up, and I didn't know why," says Walker, describing the experience of riding piggyback on a resolutely unwilling back. Her extraordinary ability to clamp on and ride out the storm has earned her the nickname of "the leech."

Jim Brown's strong point is humor. A thin man with round wire spectacles and a tiny pigtail, he can crook a finger or raise an eyebrow and turn an improvised sequence into a comic skit.

"I never knew that I had that sense of humor until I became involved in dance," he explains. "Everyone always thought of me as kind of a serious fellow. But I've found that it's very easy for me to turn a situation around and make it humorous."

Brown, 42, brings to the company a great deal of experience both in performance and life in general. Currently the artistic director of Contemporary Dancers of Alexandria, he has taught dance on the college level and spent two years as a member of a more loosely structured troupe called Free Association. At one point, he went so far as to create a 24-hour solo improvisation, which he performed in the art gallery of St. Mary's College.

"It was a most interesting experience," Brown remembers. "I brought with me a lot of newspaper, fabric, costumes, a mask, musical instruments, candles, food and some very personal things. I slept there, I ate there, I even built a little enclosure . . . My ideas would emerge and last anywhere from one to two hours and then there would be periods of rest . . . The whole experience forced me to deal with performance in another way."

Since joining Improvisations Unlimited last fall Brown has learned a lot about condensing his ideas to fit the troupe's more structured format.

"When I first started working with the company, I just couldn't get used to that time frame -- I would just be getting started and everyone else would be finishing." Now he's more in tune and pleased with his performing family.

"The difference between this company and others is that we deal with the moment, which gives our work a special element of excitement," Brown explains. "What Mim [Rosen] encourages all of us to do is not to push it. If there is something to say, it will come."