I competed naturaly for 10years.I trained for 2 hours a day back in the 1980's and and early 1990's .I was sore all the time and I couldnt get my body weight past 228lbs.
Then in 1994 I cut back my training to 45 minutes per day and 1 body part per day and my body weight shot up to 240lbs.Totally drug free.
If you look at research your natural testosterone levels & Growth Hormone levels begin to drop after45 minutes.After this happens the body begine to release cortisol.
If you ever look at a natural bodybuilder who ever dieted or over trainied they look"stringy".The reason for this is cortisol ate away all there muscle mass.
To be a top natural level bodybuilder you need to keep your workouts 45 mintes or less, train a muscle no more then once per week.Plus take in atleast 1.5 -2 grams of protein per body lb per day, along with 50 grams of L-Glutamine