Lizards hanging upside down?

Question

In the movies, when people hang upside down, I learn that we cannot do that very while because it really messes up the blood vessels in our heads.

So how do lizards and frogs hang upside down on walls for hours and hours?

Answer 1

             Because thier cold blooded like spiderman.

Answer 2

They have a very powerful heart and they are built in that way. Dont compare yourself with a lizard. They are too small to experence the force of gravity to such an extent.