Keeping lower weight helps a lot with joint wear and pain. But too much repetitive motion wears out any joint, or too much heavy use. Keeping fit helps a lot to minimize that, but you can do only so much...
Electricians wear out knees as the knees are designed to take that kind of punishment, so older electricians tend to move towards managerial roles or they suffer for that grunt work...
One example...
So, I doubt they are escaping overuse or heavy use injuries that cumulative tear you down or apart...
