New classes

I am trying to build new classes at a new studio - it happens to be a martial arts studio that is offering fitness classes.  We have put a boot camp style class and a stability ball class on the schedule and attendance has been well let's say low.  My classes are scheduled while the kids are in their karate classes and 10-12 parents will sit around and watch their kids yet we can't entice them to take classes (although the parents were the ones who initiated the idea to add classes).  Outside of Zumba, I'm struggling to figure out which would be popular classes.  Maybe they just need to be renamed with different descriptions.  Any ideas would be welcome :)  I am certified Group X Instructor and certified Personal Trainer.  Cycle is out - no room or budget for cycle bikes.