I enjoyed Nick Lane's book on mitochondria "
Power, Sex, Suicide: Mitochondria and the meaning of life" and his other books as well. He looks at how energy is used by the cell and a lot of it felt relevant, but my brain doesn't retain that sort of information any more, unfortunately.
Some people use complicated heart monitors and I think it does help them a lot but I am too ill to do much nowadays. It fascinated me that my heart rate reflected the way I felt. I wish I had known about stuff like that in my more moderate days so it would have told me, or rather gave me confidence, to stop.
Now, I just have a quick check of my fitbit and if it is too high I stop for a minute till it goes down - so one shoe on, rest another shoe whereas before I would have finished the task.
Workwell talk about switching to anaerobic respiration at a lower level than normal. Thinking about it, it must be that we go into emergency mode with normal activity, our bodies think we are running for a bus when we are just standing up. So would it be that ATP is not being produced quickly enough or that oxygen is low, or some of the chemical chain is blocked? My mind goes blank when I try to work out the biochemistry.
I do not know what the Workwell people mean by training the anaerobic system. In the videos I watched they spoke about ways of working to cut down on energy use such as putting chairs half way up some flights of stairs. The one I liked best was to put all the shopping into separate bags so that you could put away all the frozen stuff first, rest then do the fridge stuff, then have a long rest and do the everything else much later. I have started to think about activities in that way.