Technique Summary

With dumbbells in your hands, raise your shoulders to your ears.  Exhale on the way up.  Inhale on the way down.

Technique Details

Hold the dumbbells with your palms facing your body.  Stand comfortably with feet at shoulder width.  Keep your back straight and your chest out.  Keep your legs straight without locking out your knees.  Your body should be frozen in this position as you perform the exercise, with only your shoulders moving up and down.  Controlling the weight, bring your shoulders as far up as you can towards your ears.  The trapezius is a muscle that goes from behind your neck down the middle of your back.  To exercise it you shoulders should always be brought up to your back, not the front.

With lighter weight you can introduce some shoulder rotation into the exercise to involve the middle and lower portion of the trapezius.  This, however, also strains your shoulder joints.  To perform a rotation, you should lift the shoulders straight up, and then shift them all the way back as you lower the weights.

Don't flex your arms as you bend at the elbow.  This shifts the focus from your traps to your bi's.  Don't push yourself up from your legs.  This shifts the focus to your legs.  If you are having trouble preventing yourself from cheating, just perform dumbbell shrugs sitting down.  Keep you head facing forward.  Don't move it around.  Traps are prone to injury.  If you move your head around and jerk the weight you could find yourself in the position where you are stretching and flexing the muscle at the same time.  This leads to overstressing and muscle tears - not deadly, but definitely painful.