I was a little cruel to you readers - at least I did tell the girls that the pump was removing air from the flask, before I asked them to predict what would happen.
Removing air from the flask reduced the air pressure in the space around the marshmallows, which allowed the air bubbles inside the mms to expand. When I let the air back in they contracted spectacularly and looked rather wizened as their skin 'stretched' during the expansion.
On the running front - there isn't any. My quads and ITB are still giving me grief when I drive. I am managing to do the exercises most days, but I suspect I need to stretch more often, especially before I drive home.