Most of the good training programs advise that riders take a day of easy spinning after a hard day in the saddle. The theory is that the blood and oxygen flowing through the legs flushes out the toxins that build up during a hard ride.
I’ve just pioneered something new, a Zero-Recover Ride–this is a ride where you spin easily and for short distances after not a hard day in the saddle, but a day of doing nothing athletic at all. My only-semi-ridiculous idea is that you don’t want to end up shocking the system, but rather gradually working back into a stronger ride. Preferably with a mocha.