"New" Core Exercise

I went out yesterday and threw the hammer for the first time since the beginning of September, My sides and abs are killing me! I think from now on the hammer will be my exercise for the "core" the heck rolling around on a rubber ball or doing sit-ups. Try this slide, a 5lbs standard plate down the handle of you heavy hammer (for a total of 27 lbs) spin for 10 rotations, slow at first and gradually increase speed. The first 2 sets I felt myself fighting the hammer and pulling my arms in (not good). The 3rd set My arms got long because they were dead . I was using my body for the first time not my arms and shoulders. I repeat my sides and Abs are dead!!!