Rule #1 - DON’T EVER FUCKING PUT YOUR HANDS ABOVE YOUR HEAD IN AN ATTEMPT TO PREVENT YOUR HEAD FROM SMASHING INTO THE ROOF!!!
If your seatbelt doesn’t stop your head from hitting the roof… you sure as hell ain’t gonna neither.
Best case scenario - it is irrelevant, like in this video, putting up your hands did absolutely nothing.
2nd best case scenario - you only bruise your head, but have a broken wrist or 2.
Worst case scenario - Bruised spine… and broken wrist. How the hell are you going to cruise around in a wheelchair when you can’t use your hand?