Your anterior core is what we commonly think of when doing core training.  This is where the abs reside, and of course it is an extremely important part of the body.

Two of my favorite core exercises are rollouts and medicine ball slams.  Both recruit the anterior core to a tremendous degree, and by performing them back-to-back we get a nice contrast set.

What is a contrast set, you ask?  It is when one performs a heavy exercise immediately followed by a much lighter exercise recruiting the same muscles or movement pattern.  Barbell bench press and pushups is a perfect example.

Contrast sets are great because they allow you to really overload your body by providing it with heavy resistance, then making it move dynamically and explosively (at a higher rate of speed or power than would have been possible had the heavy set not been performed).  For athletes, this is a great way to increase explosiveness during a workout power phase.