I'd like to strengthen my core muscles to see if it helps with my OI, and I've heard that stronger muscles use energy more efficiently than weak ones, so maybe some of my other muscles would benefit from beefing up a bit. However, like many here, I'm very limited in energy, struggle with basic self-care most days, and have a pretty low PEM threshold. I will need to pace somehow. So, instead of taking the normal approach in exercise of doing several reps of an exercise in one go, I'd like to know: physiologically, is there any difference between doing 10 reps of an exercise in one go, or a rep every hour for ten hours? Should they be equally effective in building muscle? Should the latter course be less likely to provoke PEM? I asked a physio the first question some years ago and she didn't know.