What do the traps do?

The trapezius is a large, diamond-shaped muscle from the base of the skull to the middle of the back. The upper part lifts the shoulders towards the ears, and the middle and lower parts pull the shoulder blades together and down.

How do you train your traps?

Shrugs train the upper traps directly. Carries make them work to hold heavy loads at your sides. Rows and pull-aparts train the middle and lower parts, which help keep the shoulder blades in a good position.