The Proving Ground and San Diego MMA are two names for the same business: a multidiscipline martial arts studio next to 7-11 on Cuyamaca Street. It has classes in karate, judo, kung fu, tai chi and mixed martial arts. There are multiple instructors to accommodate this variety of styles. The interior also has a heavy bag, a tackling/submission dummy, open floor space and wrestling circles for honing your grappling skills. An office in the front sells gifts and T-shirts.