Barbell Shrugs are one of my all time favorite mass building moves for the trapezius muscles, but they also work the arms, grip, etc. They are one of those "must do" exercises for overall muscular development.
One of the best ways to maximize the effectiveness of shrugs is to do use pyramid sets, start off light for high reps, then work your way up in weight while reducing the number of reps. Then do the opposite and work your way back down again.
For example, I go through a complete workout using:
Set 1: 135 pounds for 25 reps
Set 2: 225 pounds for 15 reps
Set 3: 315 pounds for 10 reps
Set 4: 405 pounds for 10 reps
Set 5: 315 pounds for 10 reps
Set 6 225 pounds for 15 reps
Set 7: 135 pounds for 25 reps
After you perform the full pyramid set workout like this your traps will be on fire and you’ll stimulate some new muscle growth in your shoulders and upper back.
TIPS FOR BETTER SHRUGGING
1. Work in a power rack. Set the spotter pins to a point a few inches below the bottom of your range of motion, deadlift the bar into position, and shrug.
2. Stand with your feet shoulder-width apart. Don’t stagger your stance or keep your feet together—use an athletic stance as though you were deadlifting.
3. Hold the bar with your arms hanging straight down, hands just outside hip width. Transition to an alternating grip when double overhand becomes difficult.
4. Go heavy, but use a weight that allows you to perform more than 12 reps per set. The higher the reps, the greater the workload on your hands and forearms.
5. The barbell should travel straight up and down, so don’t roll your shoulders. Hold the bar in the top position for a second, then slowly lower it to a dead-hang position.