I went AFK today with 0 energy, and of course, when I came back, I had 100% energy again. So I take a couple steps -- not running, walking -- and the energy went down to 0 IMMEDIATELY and those two paces became the most I could manage. It happened every time I tried to walk; the energy immediately changed to 0.
I just thought I should report this bug, although bear in mind simply relogging solved the problem to an extent.
Sorry if this bug was not worth reporting!