Darkstone42
Oh.
I don't know if I fully agree there. If your skates are still on the ice and you are driving upwards, you are still accelerating. Once you've gone airborne, you are at your maximum possible velocity.
Keeping your skates on the ice allows you to apply a greater total force - because you can keep pushing after the initial imparct, but going airborne delivers the greatest possible instantaneous impact.
Which is more dangerous for player safety?
You start decelerating as soon as your feet leave the ice, though.
Highest greatest impact velocity is if your feet leave the ice simultaneous with making contact.