Your trapezius muscle covers your upper back and extends down to the middle of your spine. This large, powerful muscle serves multiple purposes, including providing stability to your spinal column and supporting your neck to help prevent injury. A variety of exercises allow you to train this muscle to improve the strength and power of your upper back. Consult a health care practitioner before beginning any strength training program.
Your trapezius maintains tension and posture in your cervical and upper thoracic spine, or your upper back and the base of your neck. Your trapezius also works to pull your shoulder blades up, such as when you shrug. The lower portion of your trapezius helps pull your shoulder blades back with the assistance of smaller muscles, such as the rhomboids, which lie below your lower trapezius. Your trapezius works in conjunction with your spinal erectors to control the alignment of your spinal column.
Training your trapezius involves training the muscle in two different places -- vertically and horizontally. While your lower traps work to pull your shoulder blades back, they can only be effectively trained when your torso inclines forward. Attempting to roll your shoulders back or anything similar while holding a barbell in your hands does little besides grind the bones of your shoulders together. To get the most out of your training, your training must be specific and focused.
Training your trapezius in a vertical plane can be as simple as shrugging your shoulders while holding a barbell in your hands. Hold the bar in front of you and keep your arms straight. Your trapezius is a powerful muscle -- bending your arms under the weight you can shrug will strain your biceps tendons. When shrugging a barbell, hold the shrug at the top for a count of one, then lower under control. You can use heavy dumbbells for variety.
If your gym has a chest-supported T-bar row machine, this is ideal to work your lower trapezius. Lie face-down on the pad and grip the bar with your hands approximately shoulder width apart. Instead of rowing the bar up by bending your elbows, shrug your shoulder blades back, as if you were trying to squeeze a ball between them. If you do not have this machine, lie face-down on an incline bench while holding dumbbells in your hands. Perform the same movement using the dumbbells.