by Stuart McRobert Iron Man Magazine
Q: I’ve heard that I should work my legs to help me to grow bigger arms. How can that be right?
A: Generally, at least among drug-free genetically typical bodybuilders, the body will allow only a small degree of disproportionate muscular development. For each extra muscular inch, you will usually have to build about 10 to 15 pounds of muscle throughout your physique. And to build substantial mass throughout your physique, you must train your legs effectively.
By “legs” I’m referring to the thighs—fronts and backs—but in common parlance “leg” usually refers to the thigh and the calf.
Not only do you need to work your thighs effectively in order to help build your arms, but you also need to work your back and glutes effectively. Your thigh-hip-and-back structure alone makes up about two-thirds of your body’s total muscle mass.
What’s more, you don’t need just any training for that primary structure. You need a major mass-building approach—squats or parallel-grip deadlifts rather than leg extensions, for example. When done properly, squats and parallel-grip deadlifts work the entire thigh-and-glute structure hard, and they also work the back to a degree, whereas leg extensions work just the quads. Even so, the squats and the parallel-grip deadlifts will do much more for your quads than leg extensions will.
While it’s true that the big-name bodybuilders have done lots of leg extensions, that isn’t how they built their thigh mass. Leg extensions contributed to refining their mass, but they did very little to build it.
When you know you have leg extensions to do after squats or parallel-grip deadlifts, you’ll consciously or subconsciously save something from the big exercise for the little exercise; and if you do leg extensions first, it will undermine your ability to train hard on the big exercise. Unless you give your all to squats or parallel-grip deadlifts, however, you’re unlikely to get much, if any, growth stimulation from them.
Focus mostly on the big exercises—and just a limited number of them. Keep your training abbreviated.
Of course, you want to train your arms too—but in an abbreviated way. As your overall physique grows, so will your body’s ability to grow bigger arms, but hammering away at lots of arm work and not doing full justice to the rest of your physique is unlikely to have much effect.