Nora Ephron was 65 when she felt bad about her neck. At 64, I feel bad about my elbows. It is nature's gift that I don't have to look at them. But you do, so let me apologize in advance. Maybe that's why we are invisible. We are a walking advertisement for the inevitable pull of gravity.
Most planks are static, meaning, you just hang out in a basic plank. Not this plank. Instead, there is a dynamic component to it in that you will be timing the transitions and throwing your balance off within the basic plank format.