Asked my PT, because somehow I was engaging my SC joint when I tried to lead with the chest coming up! And ohboy, she was all "yer doin it rong!" (Well, more "You will hurt your back if you keep doing this archy wiggly hyperextendy thing. Don't even try to keep your back from rounding, just try to stand up *straight*.") So that's good I guess, even though I feel fairly foolish for apparently getting it so very wrong. Sounds like it is in fact time for bodyweight while I figure out wtf on form. Argh.