Originally Posted by
kbarch
No, the definition of wasted energy is its dissipation into less useful forms such as noise, heat, and movement or the application of force in undesirable directions. Energy is conserved until it is resisted.
The legs are jointed sacks of meat. Bending and unbending them has to plow through all kinds of frictions. There's
always resistance.
And if you're high-rpm soft-spinning in beautiful form with no pedal drag, then your leg muscles are doing all kinds of things to keep that motion smooth. That doesn't come free; it's something that you can train to feel more natural and easy, but it's not something your legs "just do" with zero expenditure.