You can have cancer cells in your body right now that wont start growing for 10 years or so. The only way to find out is you have a damage cells is to have a Magentic Resonance Imaging, which is just magnetic fiels and radio wave bounceing in your body and projecting a 3d-image on a computer scream. I crack my head open a bunch of times, no biggy. There is left over Carbon Dioxide in the muscles, this is not a toxin. If your a protien dog, there will be amonia build up, this is a toxin.
Lactic acid is only temporaly.
After you had your accident. Muscles, ligiment, tendon, disk, vertbra, nerve's and nerve ending. Like i told you I injuryed my back muliple times, mostly the first 3, my lumbar verterbras are a little out of aliment, but so what. I do this 3 times a week, and I strech like a dog, plus 2 hour weekley massages and Acupunture once a week. I eat 6 capusles of essental fatty acids, which is an omega 3 oil found in fish, and seeds.