Too tired and stressed to do my intervals today, so I just did 7.5 at a moderate to easy pace.

Then I came home and did the hour of hip exercises and calf stretches the PT gave me.

He doesn't think my feet contribute at all (which I kind of have a hard time accepting, since he acknowledges they don't give me a stable base), but everything affirmative he said made perfect sense and seemed very well-founded. Weak, uneven hips (I knew that, though I guess they're even weaker than I thought) and super-tight calves (knew that too). Now I have something I can do about it.