About Fitness Evolution - Antioch, CA Fitness Evolution Antioch is a 30,000 square fitness juggernaut jam packed with top-of-the-line equipment, state-of-the-art cardio theater, Kids Club with supervised care service, tanning booths, an indoor pool, racquetball courts, a basketball court and spin studio. When you add in the full range of group fitness classes you just ran out of reasons to join a different gym. We invite you to stop on by and see our facility and learn what makes Fitness Evolution different!