The Barbell Shrug is a great exercise for strengthening the upper trapezius and building mass.
Barbell Shrugs Work
Shoulder Workouts, Trapezius Workouts
HOW TO DO BARBELL SHRUGS
Start with both hands firmly gripping the barbell, raise your shoulders straight upwards.
Doing the Exercise
Raise your shoulders straight upwards.
Slowly return to the start position and repeat.
Keep your arms, and your upper body straight as you shrug.
Dropping your chin towards your chest
Shrugging in a circular motion.