I'm still unsure as to exactly what happened in the early hours of Saturday morning. I walked about 10m, down one flight of stairs, walked another 10m, stood for a minute or so ... then collapsed.
I didn't trip and I didn't slip.
On the floor I remember feeling a bit nauseous and when Fay laid me on my back with my feet elevated I began to feel better.
All this does sound like Exercise Associated Collapse (EAC) ... but surely not after a minute or two. I've run 40 or 50 miles without EAC [in fact, it's only happened to me in the past after reaching 200k].
I'm aware that a major factor is a sudden drop in blood pressure after stopping running so could there be something else that caused my blood pressure to drop suddenly ... or is there some other mechanism at work here?
This afternoon I ran by myself, carefully, for 50 mins with no achilles or other problems at all.