In the last days I have read here and there some comments about CNS (central nervous system) fatigue produced by heavy lifting, and about allowing recovery for the CNS, not only the muscles.
It does not seem quite intuitive. I understand that the brain gives the orders and the nerves carry signals to/from the muscles. I don't understand how can they need recovery, since the work is done by the muscles, not by the cables transporting the signals or the guy in command of the machine.
Could anyone explain a little bit on this, or perhaps provide some links?