as a personal trainer, I can tell you that, in my opinion, Turkish get ups are a "show off" move
that is, it is a move that trainers give to retarded clients to "show off".
"OMG- my trainer is like incredible. He made me do this exercise called a Turkish Get up. OMG you have to see this exercise"
If you want to work your "core" (God, I hate that term,btw) just do controlled flat ground crunches
btw, "the coach"- I know you are gonna prove me wrong but that is my opinion on Turkish get ups
Furthermore, "Planks" are bullshit as well. The only reason I use them is so I can check my Text messages while my client is looking down on the floor doing a "plank" for a minute or two