This is an article by Stuart McRobert from his book brawn, and i think it'll be helpful to a lot of people here. To build muscle mass, you must increase strength. It’s that simple. You will never get huge arms, a monstrous back, a thick chest, or massive legs without lifting heavy weights. I know that probably doesn’t come as a revelation to anyone. But despite how obvious it seems, far too many people (and not just beginners) neglect power training and rarely make increasing the weights lifted in each successive workout a priority. You must get strong in the basic mass building exercises to bring about a significant increase in muscle size. One of the biggest mistakes typical bodybuilders make is when they implement specialization routines before they have the right to use them. It constantly amazes me just how many neophytes (beginners), near neophytes, and other insufficiently developed bodybuilders plunge into single-body part specialization programs in the desperate attempt to build big arms. I don’t fault them for wanting big arms, but their approach to getting them is flawed. For the typical bodybuilder who is miles away from squatting 1 ½ times their bodyweight for 20 reps (if you weigh 180 lbs., that means 20 reps with 270 lbs.), an arm specialization program is utterly inappropriate and useless. The strength and development needed to squat well over 1 ½ times bodyweight for 20 reps will build bigger arms faster then focusing on biceps and triceps training with isolation exercises. Even though squats are primarily a leg exercise, they stress and stimulate the entire body. But more importantly, if you are able to handle heavy weights in the squat, it logically follows that the rest of your body will undoubtedly be proportionally developed. It’s a rare case that you would be able to squat 1 ½ times your bodyweight and not have a substantial amount of upper body muscle mass. This is not to say that you don’t need to train arms, and squats alone will cause massive upper body growth. You will still work every body part, but you must focus on squats, deadlifts, and rows—the exercises that develop the legs, hips, and back. Once you master the power movements and are able to handle impressive poundages on those lifts, the strength and muscle you gain will translate into greater weights used in arm, shoulder and chest exercises. In every gym I’ve ever visited or trained in, there were countless teenage boys blasting away on routines, dominated by arm exercises, in the attempt to build arms like their idols. In the ‘70s, they wanted arms like Arnold Schwarzenegger, in the ‘80s Robby Robinson was a favorite and currently Mr. Olympia, Ronnie Coleman, has set the standard everyone wants to achieve. Unfortunately the 3 aforementioned men as well as most other top bodybuilders have arm development far beyond the reach of the average (or even above average) weight trainer. But arm size can be increased. However, not in the way young trainers, with physiques that don’t even have the faintest resemblance to those of bodybuilders are attempting to make progress. Thin arms, connected to narrow shoulders, fixed to shallow chest, joined to frail backs and skinny legs, don’t need body part specialization programs. Let’s not have skewed priorities. Let’s not try to put icing on the cake before the cake has been baked. Priorities Trying to stimulate a substantial increase in size in a single body part, without first having the main structures of the body in pretty impressive condition, is to have turned bodybuilding upside-down, inside-out and back to front. The typical bodybuilder simply isn’t going to get much meat on his arms, calves, shoulders, pectorals and neck unless he first builds a considerable amount of muscle around the thighs, hips and back. It simply isn’t possible—for the typical drug-free bodybuilder, that is—to add much if any size to the small areas unless the big areas are already becoming substantial. There’s a knock-on (additive) effect from the efforts to add substantial size to the thigh, hip and back structure (closely followed by upper body pushing structure-pecs and delts). The smaller muscle groups, like the biceps, and triceps will progress in size (so long as you don’t totally neglect them) pretty much in proportion to the increase in size of the big areas. It’s not a case of getting big and strong thighs, hips, back and upper-body pushing structure with everything else staying put. Far from it. As the thigh, hip, back and upper-body pushing structure grows, so does everything else. Work hard on squats and deadlifts, in addition to bench presses, overhead presses and some type of row or pulldown. Then you can add a little isolation work—curls, calf raises and neck work (but not all of this at every workout). The “Driver” The key point is that the “engine” that drives the gains in the small areas is the progress being made in the big areas. If you take it easy on the thigh and back you will, generally speaking, have trouble making gains in the other exercises, no matter how hard you work the latter. All this isn’t to say just do squats, deadlifts and upper back work, quite closely followed by some upper-body pressing work. While such a limited program will deliver good gains on these few exercises, with some knock-on effect throughout the body, it’s not a year after year program. Very abbreviated routines are great for getting gains moving, and for building a foundation for moderately expanded routines. They are fine to keep returning to on a regular basis. The other training isn’t necessary all in the same workout but spread over the week. This will maintain balance throughout the body and capitalize upon the progress made in the thigh, hip and back structure. Just remember that the thigh, hip and back structure comes first and is the “driver” (closely followed by the upper-body pushing structure) for the other exercises. These other exercises, though important in their own right, are passengers relative to the driving team. Big Arms To get big arms, get yourself on a basic program that focuses on the leg, hip and back structure without neglecting the arms themselves. As you improve your squatting ability, for reps and by say 100 pounds, your curling poundage should readily come up by 30 pounds or so if you work hard enough on your curls. This will add size to your biceps. While adding 100 pounds to your squat, you should be able to add 50-70 pounds to your bench press, for reps. This assumes you’ve put together a sound program and have worked hard on the bench. That will add size to your triceps. If you’re desperate to add a couple of inches to your upper arms you’ll need to add 30 pounds or more over your body, unless your arms are way behind the rest of you. Don’t start thinking about 17” arms, or even 16” arms so long as your bodyweight is 130, 140, 150, 160, or even 170 pounds. Few people can get big arms without having a big body. You’re unlikely to be one of the exceptions. 15 sets of arm flexor exercises, and 15 sets of isolation tricep exercises—with a few squats, deadlifts and bench presses thrown in as an afterthought—will give you a great pump and attack the arms from “all angles”. However, it won’t make your arms grow much, if at all, unless you’re already squatting and benching big poundages, or are drug-assisted or genetically gifted. As your main structures come along in size and strength (thigh, hip and back structure, and the pressing structure), the directly involved smaller body parts are brought along in size too. How can you bench press or dip impressive poundages without adding a lot of size to your triceps? How can you deadlift the house and row big weights without having the arm flexors—not to mention the shoulders and upper back—to go with those lifts? How can you squat close to 2 times bodyweight, for plenty of reps, without having a lot of muscle all over your body? The greater the development and strength of the main muscular structures of the body, the greater the size and strength potential of the small areas of the body. Think it through. Suppose you can only squat and deadlift with 200 pounds, and your arms measure about 13”. You’re unlikely to add any more than half an inch or so on them, no matter how much arm specialization you put in. However, put some real effort into the squat and deadlift, together with the bench press and a few other major basic movements. Build up the poundages by 50% or more, to the point where you can squat 300 pounds for over 10 reps, and pack on 30 pounds of muscle. Then, unless you have an unusual arm structure, you should be able to get your arms to around 16”. If you want 17” arms, plan on having to squat more than a few reps with around 2 times bodyweight, and on adding many more pounds of muscle throughout your body (unless you have a better-than-average growth potential in your upper arms). All of this arm development would have been achieved without a single concentration curl, without a single pushdown and without a single preacher curl. This lesson in priorities proves that the shortest distance between you and big arms is not a straight line to a curl bar.