I have been wondering about this too long now... been too lazy about not looking it up earlier.. or might have looked it up and forgotten about it...
so now i finally commit it to blog..
Why does it feel like you are dissipating energy (or in physical terms... power is being used up.. or work is being done continuously) when you have lifted up and are holding and object, because then ideally, physically speaking, the work done by our body on the object is ZERO..
here are the hits from google which answer that question.
Incidentally, it also also explains why some peoples hand seem to shiver when they are lifting some heavy unevenly shaped object or doing some delicate work...
..because their muscle cells are kind of contracting and expanding continuously to hold the object in place...
work: Holding something up