Use heavy weight for shrugs.
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The shrug is an isolation exercise for your trapezius, a kite-shaped muscle extending down your back and across your shoulders. This muscle can be separated into three regions -- upper, middle and lower -- and is responsible for elevating and rotating your shoulder blades. When strength training, the upper traps are considered part of your shoulders. Shrugs help to strengthen and stabilize your neck and shoulders, build muscle mass, increase your power on lifts and prevent injury.
Attend to Form
You can perform shrugs with various types of resistance -- barbell, dumbbells, Smith Machine and cable -- which can help to continually challenge your muscles. For example, begin a dumbbell shrug by standing with feet hip-width apart and feet parallel. Hold a pair of dumbbells by your sides with arms extended and palms facing each other. If the weights are nudging your outer thighs, narrow your stance. Bend your knees at a 20-degree angle and line them over your toes. Keep your head aligned with your neck. Inhale and lift your shoulders straight up as high as possible. Hold the peak position for a second, exhale and then slowly lower the weight to starting position. Perform 10 to 12 reps for three sets.
Mind the Muscles
While the primary muscle worked on a shrug is the trapezius, secondary muscles include the deltoid, forearms, erector spinae and the levator scapulae, or the muscles that hold your shoulder blades against your torso. When performing a barbell shrug, you can adjust the distance of your grip to shift the stress, according to вЂњBodybuilding AnatomyвЂќ by Nick Evans. A wider than shoulder-width grip will put more pressure on the deltoids. A narrower grip will further isolate the trapezius for work. Also, small modifications in body position will shift the stress of the exercise. For example, if you lean slightly back at the waist, the pressure of the exercise will target the upper traps at the neck.
When you carry heavy weight, your traps take on the bulk of the work. To activate your traps during shrugs, you'll need to use a significant load. While some athletes are capable of shrugging more than 300 lbs., even a less conditioned individual can shrug 60-lb. dumbbells, according to the T Nation website. Because you have to use a heavy load to strengthen the traps, incorrect form can put an enormous amount of stress on your joints as well as amplify any muscular imbalances.
Turn Up the Heat
In addition to increasing the load, you can advance the shrug by performing the exercise with one arm only. If you do the dumbbell version, shrug one weight up at a time while holding both dumbbells, according to вЂњStronger Arms and Upper BodyвЂќ by Joe Wuebben and Jim Stoppani. Turn sideways to a Smith Machine and hold the middle of the bar with your working hand. Place your other hand on your hip or on the machine for support. One arm shrugs can help you to simultaneously strengthen your core musculature and shoulder girdle.