OK... Now we have a bit of a problem on the osteoarthritis and exercise front.
.........because exercise is good for joints, lack of exercise leads to obesity and is terrible for joints!
.....but its long been believed that traumatic injury (knocks and bangs!) leads to, or exacerbates osteoarthritis, but studies now show that, in rats a least, intensive exercise also contributes to osteoarthritis. To be honest, a search of the major osteoarthritis journal Osteoarthritis and Cartilage will tell you that there are several similar studies, but this one attracted my attention; Carlos E.S. Franciozi et al 2013. The tricky thing is that this implies that there is an optimal amount of exercise for you joint health. How much is that? Sadly, we just don't know :-(
It seems sensible to conclude that the amount required to stay fit, but no more! That is bad news for MOST people, because most people either don't exercise at all or exercise massively! ...me? Well I dog walk. I don't think anyone has implicate that as hazardous for your joints yet!