But only as hard as you want to make it? I mean with the right pitched and set blade in the right length saw with the job at the right height it can be quite 'light' work? [1]
Well, it *will* also come from the cutting (see above and a bit of light aerobic work, as long as you don't overdo it <g>) and I think it would be a good plan to not spend any prolonged time on any one thing (however inefficient that might sound).
Cut a chog off, split it, stack it etc. With a chainsaw you might be inclined to cut a heap of chogs, then split / stack them all?
Cheers, T i m
[1] I agree that you can 'just' exercise some muscles, eg, by walking or cycling and that's why I also like rowing. And even when I was rowing fairly regularly, drawing my recurve (archery) bow seemed to use yet another set of muscles (I was reminded the next day ...). ;-)