I've gotten a lot of interest about my muscle gain odessy that I went through last year. For those who don't recall, my New Year's resolution for 2007 was to bring myself from 157 lbs up to 180 lbs. To be fair, I normally weighed 162 lbs but by at the end of December, 2006 I dropped down to 157 lbs. I knew it would be difficult to gain weight because in the past I could eat just about anything that I wanted and not gain a single pound (I could eat a quart of ice cream in one sitting and my weight doesn't budge).
I'm going to level with you: Diet is probably more a part of muscle gain than the exercises are. I firmly believe that for hard-gainers, gaining muscle is as hard as losing fat for most others. It requires very disciplined eating. I gained the muscle by eating a high protein and high fat diet.
The fat is the important part. While it's true that you build muscle with protein, you need the fat to tell your body to start making muscle in the first place. Your hormones are responsible for dong that and they are fat-based compounds. Read Vince Gironda's writings. He had his trainees drinking vast quantities of milk, cream, eating eggs (Yolks included!!!) and steak. He followed the same regimen and he was the guy who popularized the ripped look in bodybuilding. This is also why injectable steroids are in an oil solution. Fat is what provokes a hormonal response to build tissue.
One thing that I found with my weight gain though is that sticking to foods with their naturally occuring fat worked better than drowning my veggies with butter or drinking cream. You have to bear in mind that while I have a goal, I also have a physically demanding job. Drinking or eating straight fat just made me feel slow. The principal foods that I used to gain were whole milk, eggs, and nuts. While they're high fat foods, they never slowed me down.
One other tip that I can also give you is to make sure that you never, EVER feel hungry. If you feel hungry, you're not gaining. You might even be losing! This will probably entail eating 5-6 times a day. I told you this required discipline and I told you it wasn't easy.
As for my exericse, I tended to go with higher intensity, lower rep BW exercises as well as high intensity isometrics. Still, I think that high volume should be included, but to a lesser degree. The isometrics maintained my strength-to-Bodyeight ratio, the high intensity built the muscle, and the high volume maintained my versatility.
If you need more information or if you have questions, please feel free to post them. I'll address any further questions that you have now or in a future blog.