@Nickwba and
@23rdwave just a quick update to add to my last message there... This morning I've been doing my OAPUs with my feet together (as in, ankles touching), and this definitely adds to the difficulty, but for both the abs and for the pressing muscles in my opinion, so still roughly the same 50/50 split I mentioned previously.
For a bit of context regarding difficulty, I'd say that doing OAPUs with my feet shoulder-width apart, I could do about 10-12 reps if I went to failure, but with my feet together, I'd say about 6 reps (I've been doing comfortably tough sets of 3 this morning).
In summary, feet-together-OAPUs* are definitely a worthwhile goal if you really like your bodyweight training, and as a bonus, there's probably no 'stricter' way to do them. I plan to keep my feet together when doing them from now on, including when I elevate my feet onto a box, chair, etc.
*What do we think of 'FTOAPUs' as an abbreviation for this everyone..?
@Steve Freides a possible addition to the list in the welcome section perhaps?