The central governor theory is well known in running circles, but less so in the world of strength training I think.
To sumarize, the theory is that when your muscles tire and you're no longer able to keep up your work rate (so strength declines as you progress with your sets) it's not because of anything physical. Rather it's the mind choosing to 'shut you down' by, for example, making fewer muscle fibers available to you. The reason it does this is to stop you from damaging yourself through over-exertion. It's not a conscious thing, and it can't be overcome through will power. You can however trick it.
Now of course the body has real limits, and training will increase what the body is capable of. But as well as the physical gains through training there are massive gains to be made simply by 'reassuring' the central governor and tricking it into freeing up more resources.
The central governor is always stingy with resources because it's evolved to hold something back for real emergencies. So for example, stone age man might think his life depends upon catching the antelope for his dinner and worthy of 100% effort, but something has to be held back for a more pressing emergency - an attacking lion for example!
I'm a big believer that something like this is at play in all aspects of physical activity and training. To me I think this (or something like it) is THE most important consideration in training. And the reason why armed forces/martial arts training etc often gets better results than methods based upon sports science.
Just wondered what other peoples thoughts/experiences are in relation to this. It was CT's latest article that got me thinking about it (I think his article is spot on re the pros and cons of going all out - the key is finding the right balance....and learning to trick the central govenor).