Originally Posted by BendtheBar
Training increases quickly subside. You could try to train 8 hours per day but it won't matter. Protein synthesis rates are also impacted by cortisol... Killing yourself in the gym with high volume, high intensity and high frequency is - obviously - very stressful. This stress causes the body to release cortisol, and cortisol actually works to restrict protein synthesis.
A word of caution regarding the cortisol. The studies on which the cortisol effect are based on were done on long distance runners during long distance running.
"Less is more" was always a nice way to sell routines. But I dont think one can read too much into the cortisol studies, given that the stress produced during continuous low intensity physical activity like long distance running is very different from that produced in sharp bursts of activity (eg. weightlifting).
Here's a post from Layne Norton regarding cortisol. He explains this stuff a lot better than I ever can -
Layne Norton's Journey to the Natural Pro Stage - Page 236 - Bodybuilding.com Forums
I am not saying that high volume is the way to go - in fact, personally I like to keep my workouts short. Just saying cortisol is only of the factors to be considered in the training equation, and may be not such an important one either.