People always think it's the fights that ruin fighters but it's the sparring just as much if not more. Lets say we make a limit of power at which a punch starts becoming detrimental to your health. the majority of the total number of those damaging headshots will have been taken in sparring. If you take boxing seriously you spar about 15 rounds a week or more as an amateur and take probably around 3-5 really good shots a week. Especially the lighter weight guys really go hard in sparring. I see about one hard knockdown in sparring every week and most of the guys in my gym will just try to get up and keep going and at the very least finish the round, and most will go back in the ring 10 minutes later and keep sparring. I really think the chronic damage is caused in the gym more than anything. Things I've seen at my gym: People getting knocked down heavy and continuing without even a break. People getting knocked out and getting back into the ring 20 minutes later. A guy getting badly wobbled in sparring, and crashing his car on the way home from the gym People literally going to war with their gym rivals once a week or more for 3-6 rounds, sometimes with 10-12 oz gloves. People sparring regularily without headgear. More experienced boxers letting novices beat on them, giving them free shots.
