IN THE BIG APPLE Circus, you've got your classic big-top elements: your pretty girl dangling from an elephant, your flying trapeze acts, your teeny-tiny jumping dogs. And your multi-human balancing act (known in the business as the teeterboard act). But unlike the other numbers that rely on grace and agility, the teeterboard depends on a big tree trunk of a man who supports everyone else on his shoulders.

That man is Toni Anguelov, some 300 pounds of muscle and girth, who holds as many as half a dozen men arrayed in tiers on top of him. Anguelov, who is Bulgarian, has been in the United States for only about a year and a half, but he has 20 years of experience in the teeterboard act. Always on the bottom.

And yes, he acknowledges, sometimes it hurts.

"It's normal to hurt," he says.

The teeterboard act is popular in Bulgaria, which is home to many troupes, Anguelov says. This is the first time the act has been in the Big Apple Circus (it and many of the other acts are new to the production this year.)

It may look straightforward -- they jump on him, he stands there -- but in fact it's a complicated ballet of timing and flight. How it works is this: Three men clamber up on Anguelov's shoulders. On his command, two others launch themselves atop those three. When all is ready, Anguelov gives another command, and 16-year-old Andrei Manchev is catapulted into the air from a seesaw by two heavyweights. He spirals and lands perfectly atop the inverted pyramid. You see Anguelov buckle slightly, and the sweat pours off his brow.

"You watch all the time the small guy who has to jump," he says. "The most important thing is the little boy."

After all, there's a lot riding on his shoulders. "There's no way to make mistakes," he says. "A mistake is a life."

BIG APPLE CIRCUS -- "Bello & Friends," Friday at 11 a.m. and 7 p.m., Saturday, Sunday and Monday at 12:30 p.m. and 4:30 p.m. at Dulles Town Center, Sterling.