Originally Posted by
scoho
No, if you're not supplying power, then your muscles aren't working or burning energy, even if they are moving. If you relax your leg muscles, and I repeatedly flex and extend your leg for you, your leg muscles don't get a workout. (There might be some benefits for you, like improved range of motion in a therapy situation, but your muscles aren't working or getting fitter.)
I don't know.
I spin down a long hill and try to relax as much as possible but heart rate still goes up and I breathe heavier than at the top of the hill. That tells me I am doing more work, not less. My bike has brakes and I'm not talking about pedal back pressure to slow down.
The bike never simply drags my legs in circles. There is always tension in the muscles. Legs are always doing some work, even when traveling downhill and using brakes to slow down.
Contrast that to coasting where zero work is being done. The only way to do zero work on a fixed gear bike is to unclip.
-Tim-