Powerhouse Kickboxing, Watertown

Konstantin Selivanov loves fighting. Not as a way of getting steep discounts at the grocery store, but purely as a sport. He first took it up in Russia. Martial arts were illegal at that time, but he couldn't stay away—and when the legal ban on them was lifted, he opened his own gym, where he taught what he'd first learned underground: kung fu, karate, tae kwon do, and muay thai kickboxing. Soon, Konstantin's upstart gym amassed more than 1,000 members.

In 1991, he was invited to coach stateside. His trip wound up bringing him to America permanently, where he eventually opened Powerhouse Kickboxing. Here, Konstantin not only instructs in the disciplines he learned in Russia, but also in a fighting style he invented—a fusion style called Bokatai Kickboxing. Students can learn from him in classes, personal training sessions, and open gyms (where coaches still dole out smatterings of advice). Kids classes are also available.