A Startup Brings Circuit-Training to the Masses 9Round kicks up circuit fitness training with boxing and kickboxing inspired workouts.

Shannon Hudson was ripped. After a lifetime of martial arts and more than 80 professional kickboxing bouts, the South Carolina native was in the top shape of his life. However, he noticed, most of the people around him weren't--in fact, they weren't even close. "I thought, How do I bring the training I do to the average person?" he remembers. "I had circuit-training concepts like Curves caught in my head, that 30-minute workout model."

He took the plunge in 2008. "I begged and borrowed to open my first gym in Greenville," he says. "Within one month we had 100 members, and no sign of slowing down."

In the five years since, Hudson's concept, 9Round, has kept growing. It now has 70 U.S. units open and another 50 sold.