The wonderful thing about this exercise is that it is a compound movement that can be used to focus on one of two different muscle groups or both at once.
Select an appropriate amount of weight that you are comfortable with and load it onto the barbell. Make certain that the bar is in a position parallel to your hips. If your arms were loosely hanging by the sides of your body the bar should be slightly below the tips of your fingers. Make certain that your spotter (should you have one) is aware that you are about to begin the exercise.
Begin by firmly grasping the bar with an overhand grip slightly less than shoulder width across. Your legs should be wider than the width of your shoulders and your feet should be pointed out slightly. Bend at the knees and use your legs to pick up the bar. I cannot stress enough the potential risk for lower and upper back injury that can occur from rolling your shoulders over or bending at the waist to pick up the bar. Now, with the bar securely in your hand and your body and wrists straight, inhale and then bring the bar up parallel to your collar bone exhaling as you go. Try not to jerk the bar up. Instead, bring it up in one fast, smooth and steady motion. Do not let the bar drop suddenly instead, bring it down easily and under control. Do not swing the bar or lean backwards when performing this motion as it decreases its effectiveness.
You can focus on working either your trapezius or anterior deltoid muscle by varying how close you keep the bar to your body. Keeping the closer to your body with a slightly narrower grip will emphasize building your trapezius muscles while the antithesis focuses more on the front of the shoulder.
This exercise can be performed with a barbell, the smith machine, dumbbells or the weighted cable apparatus found on most gyms.
Sources:
- My own personal experience and knowledge gained from weight lifting with a freind who is a certified personal trainer
- Bodybuilding.com