Stand grasping smith bar with shoulder width or slightly wider overhand grip. Disengage bar by rotating bar back.
Elevate shoulders as high as possible. Lower and repeat.
Since this movement becomes more difficult as full shoulder elevation is achieved, height criteria for shoulder elevation may be needed. For example, raising shoulders until slope of shoulders becomes horizontal may be considered adequate depending upon individual body structure and range of motion with lighter weight. Also see ROM Criteria and Shoulder Shrug Errors.