Alternating curls. Stand up with your legs spread to the width of your shoulders. Hold your torso straight. Stretch your arms completely along your sides. Keeping your arm and shoulder immobile, bend your forearm. While doing this, your elbow must remain motionless. To avoid involving the front shoulder muscles, and isolate the work lid on the biceps. Return to the starting position and perform the same movements with the other arm. To avoid involving the back shoulder muscles, you must be able to do the same movements. To avoid involving the back shoulder muscles, you must be able to do the same movements with the other arm. To avoid involving the back shoulder muscles, you must be able to do the same movements with the other arm. To avoid involving the back shoulder muscles, you must be able to do the same movements with the other arm. To avoid involving the back shoulder muscles, you must be able to do the same movements with the other arm. To avoid involving the back shoulder muscles, you must be able to do the same movements with the other arm. To avoid involving the back shoulder muscles, you must be able to do the same movements with the other arm.