I found this piece from Justin Harris and I wanted to put it up because I found it interesting. While I often have to use terms with "CNS" in it because so many believe in this theory (created and perpetuated by bro-science) in relation to training, I have never really believed in the whole "CNS burnout" theory in relation to lifting weights. As Justin notes here, you'll hear this term thrown all over the place on message boards but there isn't any peer reviewed material backing up this bro-science. If anyone can post any up feel free to do so. I personally think it was started by the LSCN master himself. Now you have all of these minions running around spouting it off like it's a scientifically proven theory. I think a lot of it started after Mike Mentzer and his HIT theories resurfaced about a decade and a half ago. People started chanting about how training to failure all the time would result in adrenal burn out, with literally no evidence behind this.
Since then DoggCrapp has had people training to failure over and over again on multiple exercises in a session, 20 rep squats, and high rep deadlifts. All in a week, and what happened? People ate a lot and grew like crazy. Even from a bro-science standpoint, if CNS burnout and adrenal fatigue were true, that's the one program that would have proven it. Yet people just got big and strong on it.
From Harris -
"I won't get too involved with the CNS training and strength sports, but I don't get too excited about that concept either.
Adrenal fatigue is thrown around quite frequently these days and I don't really know why. There is no medically recognized disease of adrenal fatigue. If you look into the term adrenal fatigue you'll find many articles posted on bodybuilding and powerlifting forums, but you'll find no scientific or peer reviewed articles on the subject.
If you search for peer reviewed journals on adrenal insufficiency, you'll find addison's disease, a disease which is caused when the adrenal glands do not produce enough of the hormone "cortisol."
This is the exact opposite of what people write about when mentioning adrenal fatigue. They talk about excessive cortisol production from various forms of stress. Adrenal insufficiency is exactly the opposite of this.
The central nervous system and the peripheral nervous system are quite different systems. The system that is most readily affected by training and forms of physical stress is the somatic branch of the peripheral nervous system.
The PNS connects the "body" to the CNS and is exposed to injury and toxins in ways the CNS isn't. The CNS is hidden away in the brain and spine and protected by the blood-brain barrier.
Specialized strength training is important and has come a long way, but I believe there can be too much specialization. Specialization to the point of limiting progress and variance in physical stimulus isn't progress.
I've always trained to get bigger muscles by using heavier and heavier weights. I don't know whether that is bodybuilding training or powerlifting training.
I know that my training didn't really change a whole lot between training for football, training for bodybuilding, and training for powerlifting and I did well in each of them. Perhaps I could have done better with more specialized training, but I have too much fun at the gym to stress about those things.
I'm not here to get in a debate about the CNS. There are people who've had success with all forms of training. I am never one to discourage anyone from doing something that has brought themselves and their clients success. My feelings on the subject stem from what I understand about psychopharmacology and how it is affected from physical stimulus."