I understand and appreciate the value of conditioning. The concern I'm raising is that some people seem to be unaware of some things that canNOT be conditioned. Knee cartilage is one of them. It will be fine until it isn't. Muscles can strengthened to carry heavier weight. Bones can be strengthened to bear heavier loads. Ligament flexibility can be maintained. But cartilage cannot be "conditioned". It boils down to simple physics -- stronger bones carrying heavier loads moved by stronger muscles directly puts more stress on the knee cartilage.

My understanding is that while we may be able to somewhat control the rate of wear, knee cartilage can only wear, not be "built up" in the sense that bones and muscles can.