I've written a full article on this topic and it's available on this forum. The problem that I see is the terminology that is been used or not used in this instance to solve this seemingly confusing scenario. I'll make it clear...
1. Overtraining....yes every Tom Dick and Jane talks about it
2. Under-recovering...as above
3. Over-reaching...hardly anyone talks or knows about it.
For the average trainee, I do not believe in a state of overtraining, but I do believe in a state of under-recovering. That is to say, what one does in the gym can not be hard enough to be called overtraining (I'll explain why in a second). However, what one does
not do once they leave the gym, can and does lead to under-recovering, which in turn causes one to not progress as they should, had they ticked all the boxes that go to make one recover properly, namely rest and sleep, nutrition/enough calories and so on and so forth.
Getting back to the overtraining bit and why I consider it near impossible for the average trainee to experience it, based on his gym workout. The main reason for this phenomenon lies with human psychology and the way it affects our physical exertion in that gym. If you truly believe that you're giving it your best during your gym workouts, I'm here to argue the point that you're not. Mmm, so how would I know when I'm giving it my best and what is it that is needed for me to give it my best? In two words: external influence. That is what you need, that is what everyone needs to guarantee true maximum effort.
And that's precisely where over-reaching (and therefore true overtraining if you like) comes in. Confused? No need to be. Think of it this way: one action is deliberate and very much calculated (that is the over-reaching) you were able to attain thanks to that external influence, whilst the other state (that your average trainee in the gym calls overtraining), is no more than some serious lack of under-recovering. A fight with your girlfriend or your boss at work can reduce your ability to recover. It doesn't take much, hence I've always emphasised the positive psychology of an athlete's mind playing a huge part in his ability to make progress. Some athletes are better managers of their stress levels, and know how to handle and control such external and potentially negative influences.
Here's the small article I've written on the subject:
Overtraining or under-recovering?