NEW YORK -- All stage auditions may be grueling but one held downtown last week has got to be one of the hardest.

First, applicants got into harnesses and then up on a treadmill high off the ground. They walked, then ran, then sprinted for their lives. They couldn't forget to keep acting -- even after the gunshot.

Such was the task ahead for some 40 men and women as they tried landing a job with the Argentinian multisensory show "Fuerza Bruta," now celebrating its 10th anniversary.

"It's a long-running show and we hope it will continue to be a long-running show," said Brooke Miyasaki, a performer who also acts as a dance captain. "We need to infuse it with new spirit and new energy."

"Fuerza Bruta" is an immersive theatrical experience in which seven women and four men -- and one musician -- act out a series of gravity-defying stunts set against thumping club music.

In the show, four women writhe in a massive pool lowered over the audience's heads. Performers bounce off metallic-covered walls or seem to hang suspended in tubes filled with rushing air. A key image is of a man in a white suit on a treadmill, smashing though obstacles, until a bullet strikes his side. Somehow, he keeps going.

At the audition, Miyasaki and Liam Lane, a fellow performer and also a dance captain, gave each applicant a moment on the treadmill at its home at the Daryl Roth Theatre in Union Square.

"Walk!" Lane said into a microphone and the candidates did. "Slow run!" he shouted and they began running. "Fast run!" he bellowed and the treadmill whined. "Bang!" he yelled and the applicants clutched their side. They kept running, slowed to a stop, and then started walking again, heads held high.

"I think you really see someone's energy and spirit when they're digging in to survive on that treadmill," said Lane. "You feel bad putting them up there sometimes but when you see someone's face change because they want to move forward, they want to keep going, it says so much about their character."

The show was created by artistic director Diqui James, who also helped make "De La Guarda." His new one is being constantly updated and tweaked. Live drumming and singing were added last year, and projections have just been put into the mix.

"We grow a lot. We learn a lot And we have a really strong team. After 10 years, we are in very good shape," said James, who has four companies -- ones based in New York and Buenos Aires, one now at a festival in Budapest and one touring China. Peru is next.

In New York, the 40 hopefuls were culled from some 800 submissions. Only 10 men and 10 women from the treadmill group will be asked back to don harnesses again and demonstrate their aerial skills. Only four men and four women will make the final cut.

Lane, who is married Miyasaki, said "Fuerza Bruta" needs applicants with some unusual skills. They often come from backgrounds in gymnastics, circus or dance.

"You're looking for people who are incredibly physically fit. People who can dance. People who can act and have a spirit -- a certain energy. And have rhythm, because they have to play the drums," he said. "So there are a lot of different things that you're looking for."

Cast members rotate through the various parts every night so each applicant must be able to handle the whole show. "It keeps us on our toes," said Lane. "It gives certain muscles a rest."

James said that when he was starting the show 10 years ago it was hard finding actors to do what he wanted. He's now seen the pool of applicants rise as performers embrace multiple skills and sculpt their bodies. But beyond endurance and muscles, he also needs people who can be vulnerable.

"What is difficult is to find people who have a big, expressive range," he said. "You can find performers who can be really tough, highly energetic and expressive, but then they can't slow down and breathe and connect."