I don’t think it’s super clear from your post. In this friends case it was the NFL part that caused the damage. Not the fitness part. I once did a boxing clas

I don’t think it’s super clear from your post. In this friends case it was the NFL part that caused the damage. Not the fitness part. I once did a boxing class. The day we did drills with with those boxing pads that require 2 hands to hold up, my head was throbbing for the rest of the day. Tried it again and same thing. Then I quit. Clearly I cannot take a serious punch.