The nature of CNS fatigue?

[Rain]

First off, this may have been covered elsewhere. If so, I just haven't been able to understand it or didn't find it, so please bear with me.

My question:

I understand the principles of HST, and that we are trying to avoid CNS fatigue, to be able to continously keep training for optimal growth. But I'm curios about what the essence of CNS fatigue really is -- I mean, what happens "behind the scenes" when the CNS become fatigued? Lower testosterone levels? Less GH? Less...something?

OK, we become tired and cannot train as hard or as frequent as we want. But is it possible to explain (in layman's terms) what causes this? I'm no scientist, just trying to piece together the whole picture on a level I can understand and convey to other people.

Best regards,
/ R

 

[Hardrock]

I'm also interested in this topic. I've always read that one sign of CNS fatigue/overtraining is an elevated heart rate above normal resting heart rate upon waking up in the a.m. Another sign would be loss of strength from one workout to the next. Another personal indicator for me is when my eyelids start spasming (no kidding- I know that I'm close to the edge when that starts happening).One thing I've noticed with HST is a run down feeling, especially towards the end of a microcycle with the rep maxes. I never use to experience this with conventional split programs, of course I was also younger when I did conventional splits.