: Your second argument is also rather weak as it is based only on the
: unsupported assertion that “our bodies have a hard lifetime limit how many
: times we can bend our knees or swing our arms” (I’ll recant if/when
: evidence is provided that supports your assertion of this hard lifetime
: limit). I would hold more to the thought that the wear and tear on the
: body has less to do with the number of repetitions and more to do with how
: the forces are applied.

I can't prove it but I suspect we can wear our bodied out with hard repetitions. You see football players with bad knee cart ledge all the time. I worked out with weights most of my life (73 now) and one of the things I way over did was set ups. When I was 43 I was on a slant board doing setups and I heard this strange clicking in my back. Not long afterwards I had a herniated disk. I did double my weight bench presses, and now I have bad shoulders. A friend of mines workout specialty was heavy swats. He had both knees replaced a few years ago. Just my observations.

John