Q:

Is it possible to workout too long?

Is it possible to workout too long? If so, why?
At the beginning of this year I started really working hard at the gym and would lose track of time and would sometimes workout for almost 2.5 hours. The workouts usually consisted of 2+ hours of intense weight lifting followed by 15-20 minutes of ab workouts. I never had any negative side effects from it though. After doing some research, I noticed a lot of people thought this was too long. 
I may need to create a separate question for this, but I've recently read that during long workouts BCAAs may be beneficial. Would adding BCAAs mid-workout allow you to increase the workout length?

Edit: Here is an example of some of the things I came across. It seems that a lot of people say things like "Don't workout longer than an hour." I want to know why, and just blaming it on overtraining is not a sufficient answer. 
This article says this:
"And after sixty minutes your body will start to produce less testosterone and more 
cortisol, which is a hormone that eats muscle tissue and increases body fat storage."

Is this true?

A:

There are two questions here: First, can you work out too long in one session? and Second, was I working out too long?  The correct answer needs to frame the conclusion with the reasoning.

Can you work out too long in one session?

You will eventually reach a point where your body will be so fatigued and all your energy systems will be so depleted that you simply can't move anymore.  So in absolute terms, yes you can work out too long.
I spent all day moving and carrying heavy things quite a few years ago.  While we did have some help, they left before the move was finished.  At the end of the day I could barely get my legs into the car.  That was after well over 8 hours worth of moving work.
In practical terms, no most people will not reach the level of fatigue where they need help getting to their car.

Was I working out too long?

Since you felt no adverse affects, the short answer is no you were not working out too long.  You were still moving as well as you normally do.

Where does this 1 hour threshold come from?

Bodybuilders work very hard to keep their bodies primarily in an anabolic state, and try to avoid catabolism as much as possible.  If you train with sufficient intensity, after about an hour the training stimulus becomes more catabolic.  Since they are concerned with increasing the size and refining the shape of their muscle, that's considered a bad thing.
Power lifters on the other hand often spend a couple hours in the gym and they get stronger.  However, power lifters are not as concerned with the size and shape of their muscle.  The outlook is simply more mass moves more weight, and more muscle gives you more room to get stronger.
I believe the end result is that the short term hormonal changes after an hour of training is catabolic, the long term effect of recovery overcomes the effects of that catabolism.
The key to all of this is managing your fatigue levels and recovery to be able to do more work over time.

