I am a 39 year old body builder and personal trainer. I have been seriously body building for 5 years. In that time, I have made a lot of progress, am happy with my strength and muscle tone. However, I have a hard time gaining additional muscle mass. It seems that I have hit a wall. I am 5'6" and weigh 162lbs. I have a medium bone structure. I have tried so many things before. Is there anyone out there, with a similar body type and height who would have any suggestions for gaining weight and muscle mass. Currently, I am stacking (muscletech, anotesten and nortesten). Thanks.