(Watch this video on FullScreen by going to thefastfit YouTube channel http://www.youtube.com/thefastfit)
This is an advanced version of regular Knee-Ins that you would do on the floor. By using a medicine ball, the normal stability you would have in a pushup position is taken away forcing you to use more core muscles to maintain balance and stabilization.
If you've never done Knee-Ins before, start by doing them on the floor from a pushup hold position. Using hip flexion and contracting your abs bring one knee at a time "in" to the elbow. At first you can do right knee to the right elbow & left knee to the left elbow, and as you improve your core strength you can make the exercise more challenging by bringing your knees to the opposite elbow.
Once you've mastered Knee-Ins off the floor try it now using a Med-Ball or even a basketball that has plenty of air in it. The constant movement and instability of trying to balance on an unstable surface makes this move a fantastic and high quality exercise. Try it out!
For more exercises and workouts check back here or on TheFastFit YouTube Channel and Facebook page: