The Cardio Grind, Los Angeles

Flashback to the 1990s, and there’s a good chance of finding one of two items in nearly any household: a Furby and a Billy Blanks Tae Bo tape. While the talking pet’s popularity may have diminished before the new millennium, Tae Bo still holds a predominant market in the fitness world. Inside group-fitness mecca Its All U Fitness, Kanika Brock—once an apprentice of Billy Blanks—pumps up heart rates with the fast-paced martial-arts-inspired cardio workout. And she’s not the only Tae Bo expert calling the kicks and punches; the founding father himself stops in on the occasional Sunday to lead classes and demonstrate how he can open a pickle jar with his fist.

Of course, uppercuts and jabs aren’t for everyone, so Its All U offers a few other group classes, including Zumba—led by native Cuban Danny—and Barre Control—which evokes raw athleticism with challenging ballet-inspired moves—taught by Michelle. Perhaps the most unique instructor is Maxi B. When she isn’t cooking healthful meals as a professional chef, the Workout Naughty Style enthusiast is showing pupils how to combine classic jazz with sultry burlesque and tactics for sneaking in past curfew.