"I think we're discovering the power of our bent knees and extended hips, which directly translates to our work in karate," said Sensei Michelle Gay, one of Master Yu's students.

After executing the routine, which gets progressively longer, Master Yu looks to the class. "Push on me," he says to a student. Then, to the class's amazement, this 79-year-old man speeds up, forcing the student across the room. "Now, I kill you," he says, laughing.

Master Yu highlights skills within the routine - slow-motion punches or changing weight distribution - and demonstrates their practicality in a real fight. His real-time movements are specific and connected to the floor, allowing him to control his opponent without effort.

This "supple" force is a constant theme in his classes. Tai chi is about internal force, not softness. Shaolin, meanwhile, utilizes external force. Master Yu believes martial artists must practice both internal and external force. Form is paramount.

Born in Shanghai in 1929, Master Yu Cheng-hsiang studied Shaolin at age 15 to control asthma. In 1949, he moved to Taiwan, where he studied Yang-style tai chi with Cheng Man-ching. Ten years later, Master Yu was teaching teachers. He came to New York in 1979 where he continues to teach. Prominent students have included Maggie Newman and Joseph Zeisky.

SMAI sells Master Yu's instructional DVDs for $65 and $75 as well as tai chi shoes for $10.