That's 1 rep. Why it rocks: Kneeling medicine ball slams are an awesome exercise that develop rotational core strength. That skill is important for everyday functional movements, says Stewart.

"This quick five-minute deep core workout is all you need, and we’re keeping it simple with just a Pilates ball." How to do ...

Here are the 10 best deep core exercises that you can incorporate into any routine, according to trainers. Meet the experts: Jessica Chellsen, DPT, CSCS, is a doctor of physical therapy ...