I want to also state that I realize the CNS is conditioned for beginners. It has to be to lift more. What I am in essence saying is that for many beginners, muscle growth is more of a shock reaction to the training stimulus, and comes fast and easy.
In this article by Casey Butt, we see that most muscle is gained in year's 1 and 2...beginner to intermediate trainees...
Rate of Drug-Free Muscle Gain
An average trainee can gain about 15-16 pounds of muscle in year one. Every year after, and boiled down for the sake of simplicity, gains are cut in half after that.
Year 1 = 16 pounds
Year 2 = 8 pounds
Year 3 = 4 pounds
Year 4 = 2 pounds
Year 5...welcome to the grind....
So, because most gains by naturals happen as beginners, and that few gains happen when we get into the level of intermediate to advanced, and are pushing for powerlifting style poundages, it seems that the greatest factor for muscle growth is the physiological and hormonal response to the initial shock of training.
Yes, their CNS is getting conditioned during this time, but I don't believe that the central nervous system is the prime mover and prime factor in the gains.
With that said, I reserve the right to be wrong. I am basing this analysis on what I know. And I have not read anything about the corrulation between beginning lifter's CNS and their rate of muscle growth.
Since intermediate and advanced lifters gain very little muscle, again we're talking natural, but work the hardest at CNS conditioning, I don't see the connection between training the CNS, fiber recruitment, and muscle gains.
Maybe I'm completely wrong about just how conditioned a beginner's CNS is becoming the first two years?