I keep having pain (the dreaded "hot foot") in my left foot when I ride for more than a couple hours. So I'm trying to understand the mechanism in hopes of finding a work-around. {Note: I tried using the button type orthotics, but they tend to make my foot cramp up, which is even worse than "hot foot".}

Here's the deal:
--If I ride in a fairly high (ie, hard) gear at a moderate cadence and mash the pedals, I tend to not have any pain. Unfortunately, there are some nasty hills here and the only way I can surmount them is to spin in an easier gear.
--If I ride in a easy gear at high cadence and lightly push on the pedals, the foot pain ultimately happens. If I subsequently switch to a higher gear, press harder on the pedals, and slow my cadence, then the pain subsides.

I would have expected the foot pain to occur when I mash the pedals in a high gear. Anyone have a theory as to why the opposite is happening?