A lot of people think that the main function of the abdominal musculature is to do sit ups on a swiss ball. This is however not how we were designed, as there were no swiss balls when spears and clubs were the key to catching some dinner. The main function of the abdominal and lower back musculature, in association with some pelvic muscles is to stabilize the spine under load or in any dynamic motion. Thus the "abs" are worked more effectively squatting than doing bosu crunches. Today's workout will require a lot of this core strength and stability even though the "abs" are not the primary movers.   

Today's Workout

As many rounds as possible in 15 minutes of:

10 Supine Ring Pull-ups
10 "True" Pushups

Post number of rounds completed to comments.

*Definition of Supine – The supine position is a position of the body; lying down with the face up.
*To perform Sup Ring PUs, set the rings so your back is off the ground, place heels on a box and pull your chest to your hands. 
*True Push Ups are done with both hands and feet balancing on parallets, make sure you get your chest below parallel.