1. Ball crunch with medicine ball throw 


Core, abs, shoulders

Lie flat on your back holding a medicine ball at chest level. Lift your shoulders off the floor and crunch. Once at the top of your crunch, throw the medicine ball forward to someone standing in front of you, or against a wall. Catch the ball on the bounce back, roll back down to starting position. Repeat and complete as many as you can in the recommended amount of work time.

NEXT: Alternating push-up