Billy Siegenfeld, artistic director of the ten-year-old Jump Rhythm Jazz Project, makes the point that you gotta go down to go up. During a rehearsal he asks his dancers to dig their feet into the floor--"Dig down into your roots," he says. And he bemoans the fact that so many dancers are trained to lift their weight, pulling up thighs, chests, and heads in a way that interferes with the body's natural polyrhythms. Exploring rhythm is the raison d'etre of his choreography, which is set to various jazz pieces--never the rock 'n' roll that some jazz-dance troupes favor. In Getting There (which won the 1994 Jazz Dance World Congress award for choreography), a group of people at first isolated from one another form a community based on shared rhythms; the revision Siegenfeld has done for this concert emphasizes percussive moves off the beat, hand claps and body slaps that work against the music yet heighten our appreciation of it. The new duet he'll perform with associate artistic director Jeannie Hill, You Make Me Feel So Young, is filled with lyrical bursts of movement and finally erupts into open, free, barely contained hilarity. Siegenfeld also previews the first section of a three-part piece commissioned by the Limon Dance Company, If Winter (to be premiered at Jacob's Pillow in June). Set to Patricia Barber's recording of "Early Autumn," this section focuses on hands and arms, not steps--though there's enough flat-out running to leave the dancers panting. What's perhaps most remarkable about Siegenfeld's choreography--which always has the same imperative, to play with the music--is its variety. Also on the program are his Joy Spring, No Way Out, Released in Their Own Custody, Poppy and Lou, and Lunacy, plus Hill's Play Dirty and an adaptation of Eddie Brown's Bye Bye Blackbird. Dance Center of Columbia College, 1306 S. Michigan, 312-344-8300. Opens Thursday, March 15, 8 PM. Through March 17: Friday, 8 PM; Saturday, 3 and 8 PM. Note: There will be a postperformance company benefit reception Thursday, March 15; $100-$300. Call 847-869-2263.