I would gently argue with a couple of these points. First, VO2 and sarcopenia, while inevitable, can be vastly reduced in terms of their precipitous decline with exercise- both aerobic and strength. There are far too many research papers and studies which show this. For my part, at 67, I just did a test for my VO2 and my cardiovascular system is as efficient as a twenty year old's. That doesn't make me an outlier, for there are plenty of folks like me who work very hard late in life. It is true that there is eventual degradation. The point is that all of us can stave that off to a very great degree with hard work. The decline does not have to be signficant. In fact, for many we improve with age, and to your point, many of us get better and better with endurance as we age. My hand is up here. I am righteously gobsmacked at what my body can do -not STILL do, not compared to others, but what my aging body consistently delivers in terms of strength and endurance as I head into my seventies.