In Exercise Ball: Bosu Ball?: Training Essentials and Workouts: Runner's World Forums

You could probably do just as well with a regular stability ball. Where I would find the Bosu Ball hard-to-replace is for squats (with the rounded-end down). You could probably do just as well with a regular stability ball. I'll bet this is what you're thinking of: I was also thinking the combination of a regular swiss ball and the disk pillow ( as this outlet calls it) would offer more variety fo ...Exercise Ball