I think that sports cripples, but not tempers, because I'm an athlete and my sport is alpine ski. On my personal experience I had two serious injuries, and I also braked my arms 3 times, and sometimes it hurts on the weather. My grandma, also was an athlete and now she have problems with she's knees, so that is mean that sprots cripples.
I can not agree with you, because as I know, sport always helped, helps and will help promote health. For example to take an old people, who are over 60, for what they are do exercises and jogging? To be in good shape and to strengthen their immune system. Or people wake up a bit earlier for what? To do a stretching, to temper their body.
So, you think that this is normal for old people? I know that only swimming can temper your organism in old age, and this stretchings, such as jogging or walking, it is only got worse for the elderly. If to talk about professionl sport, i'm sure that it cripples. No one sports career will not pass without any injury, and this injury will impact on your health in future.
If to talk about professional sport, so here depends on athlete, depends on his health or his immune system, on whom it heals like on dog, on whom it can heals all life, as I said it depends on person. I agree with you that swimming helps to old people strengthen their organism, but jogging and some stretching also tempers their health, they know that they do, do that for their advantage.