Tough call, if your head is actually very close to the cage & the cage is padded then you are less likely to suffer injury than if its say 4 or five inches away. Try it, hold your fist 1" from a concrete wall , then hit the wall with all force available---didnt really hurt did it?. Now hold your fist 12" from the wall & repeat the process----is there any blood?
Time-speed-distance.