Regardless of body type, it takes plenty of heavy exercise to increase muscle size. In other words, the heavier the weights you use, the larger your muscle size. Still, you must train for your body type. Here is a very basic building routine for that guy that can't seem to put on weight - The Skinny Dude (aka the ectomorph).
Ectomorph, a human physical type (somatotype) tending toward linearity, as determined by the physique-classification system developed by the American psychologist W.H. Sheldon. Although classification by the Sheldon system is not absolute, a person is classed as an ectomorph if ectomorphy predominates over endomorphy and mesomorphy in his body build.
The extreme ectomorph has a thin face with high forehead and receding chin; narrow chest and abdomen; a narrow heart; rather long, thin arms and legs; little body fat and little muscle; but a large skin surface and a large nervous system. If well fed, he does not gain weight easily; if he becomes fat, he is still considered an ectomorph, only overweight. - encyclopedia britannica
Ectomorphs must be careful not to overtrain, since they will be very prone to do so. And overtraining very quickly halts any muscle gains dead in their tracks. The following is a jumping off point for your training. You'll have to adapt it to your own body depending on your age, experience, and fitness level.
Ectomorphs can make their best gains with 3-6 sets per body part, depending on how experienced you are. Even the most experienced skinny builder might overtrain on more than 6-8 set per body part, merely sharpening your physique instead of gaining more size. With less than three months of training, three sets per body part would be most appropriate (add one more set of each exercise per six months of training, up to six sets of each).
Here's a suitable beginning size gain workout:
Standing Calf Machine
Stiff Leg Deadlift
Lying Triceps Extensions
On exercises that recommend 10-15 reps, do a number of repetitions within that range. The 10/8/6 reps means one set of 10, add weight and do one set of 8, and add weight again for a set of 6. The weight jumps should be roughly 15-20% between sets. So if 100 is your first set on the squat, the second would be 120 and the third 140. It's essential to push hard to steadily increase exercise poundage. The final repetition of the third set should be absolutely the last rep you can do.
Only by going close to "failure" like this can you be assured of getting the most out of each exercise. However, while the final set should be to max, the sets leading up to it should be 75-90% of maximum. These first sets build muscle but also warm up your muscles and joints for the all-out final set. Without a good warm-up, you are likely to injure yourself. You will also not be able to thoroughly stimulate your muscles with the final set unless fully warmed up. It's difficult for me to tell you how fast you should be progressing, because everyone is different and everyone moves at a different pace.
While you may progress more quickly or slowly, you should be able to increase leg and back exercises about 5 five pounds per week and other body parts five pounds every other week. These are very general guidelines for a very general body type. This routine acts as a base for you to build on. Happy Building!
Success! Feel free to
or head to your