Qusetion:
I have a problem developing my shoulders and traps. Are four sets of 10-12 reps inadequate, or are shoulders and traps more difficult to bulk up than the rest of the body? — Marcel Dentremont

Answer:
Shoulders and traps represent a complex muscle group. They call upon groups of muscles, such as the back and arms, for stabilization, support or leverage before they can do their work. That means stress has to pass through those ancillary muscle groups before it can fatigue your shoulders and traps. In other words, a shoulder or trap exercise is more indirect and, therefore, more inefficient.

None of this, however, creates a real obstacle to building the shoulders and traps. They can still accumulate as much mass as biceps and triceps, it's just that there's a lag time. You have to work harder, train more, lift heavier and wait longer for the results. Be assured, though, that if you make an extra effort to build them, they will come.

To implement all this, I recommend that you train each of these bodyparts on separate days, combining your shoulder workout with chest on one day, back with biceps on another day, then traps on either leg or triceps day.

For shoulders, do four sets of standing dumbbell lateral raises, four sets of standing or seated militaries (front barbell presses), four sets of seated dumbbell presses and, finally, four sets of bent dumbbell lateral raises. To build bowling-ball mass into your deltoids, make sure they do the work. Keep your traps low and out of the movement.

For traps, do four sets of upright barbell rows, four sets of barbell shrugs and four sets of dumbbell shrugs. Peak contractions are especially effective for traps.

Hit each of these bodyparts with equal intensity and equal consistency, and I assure you that they will ultimately blend together as one massive muscle group. Oops, there I go again with one of those operative words: "Ultimately" does not mean tomorrow. It doesn't even mean next year or the year after that. It has no timetable, and if you can accept that, even enjoy it, you will someday have the shoulders of giants.