Here is my stepson, Janak and SingingCyclist when he posts here, learning to split some kindlin'. Good stuff that woodchopping. Better be bending the knees. Twisting. Core. Like cycling, you've got to be moving from a stable platform or core. Otherwise, much energy goes wasted instead of into the pedals or between the woodgrains.
As you can see from the reproduced page below, we've even invented an exercise called the Woodchopper since fewer folks chop much wood these days. The page is from the book Cycling Anatomy which I reviewed here. There is also a previous post where I referenced the Medicine Ball Throw from the same book.
Keep it trained on that precise point where the grains meet,