Hi Trevor, I agree with some of the content of your posts. I am a firm believer in "use it or lose it" and have done high levels of exercise for over twenty five years {now aged 46}. However, one important thing to remember is the ankle was designed {after it evolved} for lots of walking and running. The shoulder is not designed for doing 1000 shoulder presses in one hit for example. It will wear out and then break. The same is true for our elbows when wfping, it is not a natural movement that we can do for hour after hour without getting problems.
I did a block of flats this morning, worked from 08:00 to 14:00 with a thirty minute break. My neck was very sore during the higher windows after a while, not much I can do about that but where possible, I cupped the base of the pole in the right hand and walked or rocked to and fro, much easier on the elbow joints.