My fall from 2 stories up followed by bay window cross the neck didnt manifest until 4 years past reconstructive surgeries and phys therapy. It was like a timed delay until limbs were on the mendidk maybe. I think looking at boxers etc it can withstand a certain amount of punishment, but not severe sudden ones. Probably depends upon a variety of factors including genetics. I suffered two very severe head traumas in a year and a half period.