Cool! This stuff is fascinating!

It is fun to think about the path from glucose to power at the cranks. Somehow the glucose has to turn into muscle contraction, and the ATP is a key link in that chain. But from muscle contraction to power at the cranks - maybe training can reduce inefficiencies there, too.

Surely there is a lot more technique involved with swimming than with biking. But still... a nice smooth spinning of the pedals is not quite trivial, either.

One funny thing to think about when considering the conversion of food energy to mechanical energy. Holding up some weight, just standing still holding weights in one's hands - pick your favorite position, arms down or straight out in front, whatever. No mechanical work is being done at all. But surely there are muscles contracting and glucose molecules getting metabolized.

This sort of thing can happen, surely happens, when pedaling a bike. For example, how much downward pressure is kept on the pedal as it reaches bottom dead center? That is muscular work that performs no mechanical work.

Yeah, I carry my 5 pound Kryptonite lock up the hills, then dissipate all that mechanical energy through my brakes and rims on the way back down the hill! Crazy!