The Wood Chop Exercise for Abdominal and Oblique Muscles

I think one key to training abdominal/oblique muscles is to ad some variety.  Here's an exercise you can try called the wood chop (also called wood chopper; cable chop).  The clips below show a few variations.

Diagonal Cable Chop



Diagonal Cable Chop (with no bending at the waist)



Horizontal Cable Chop



Reverse Cable Chop