Whomp!

That's the sound of a body after it dives from a high place and lands in an all-out, smack-down belly-flop on a gym mat.

There's a lot of "whomping" in "Wild Blue Yonder," a remarkable program of gymnastic dance performed by the noted troupe STREB before a packed Bagley Wright Theatre at Bumbershoot on Saturday. Though too long at 90 minutes, and rather clinical in presentation, it's also an astonishing display of the human urge to defeat gravity.

Looking like bikeless Tour de France racers in their sleek, red-and-black body suits, famed choreographer Elizabeth Streb's dancers are trained, literally within an inch of their lives, to test the limits of human reach and buoyancy, in this abstract tribute to a century of human-engineered flight.

Dancers swing high on bungee cords while cohorts dive and roll under their feet, and barely avoid getting kicked. Two movers, tethered by a kind of dog leash, strain apart, drag and smash into one another. And when the troupe runs and slams full-face into a large pane of Plexiglas ... well, yikes. And ouch.

The most-perilous passage has these intrepid performers running, walking and rolling between swinging pendulums weighted by large, concrete blocks. The hesitation of a millisecond, and ... .

Such scary antics are business as usual for members of this New York City-based outfit, who have a rehearsal hall named SLAM (Streb Lab for Action Mechanics) and an ongoing dare with gravity.

The dancers display rigorous discipline and good humor throughout, and it's fun hearing them shout commands ("Up! Turn! Drop!") like circus acrobats. They're accompanied by a montage of projected film images and titles, and interludes of buzzing electronic music — all vastly upstaged by the resilient bodies.

Misha Berson: mberson@seattletimes.com