1) Stand with your feet shoulder width apart with a slight bend in your knees. Grab the barbell with your elbows behind your body and your palms facing upward.
Pull your shoulder blades back and keep a bend in your elbows so that you can comfortably keep your elbows behind your torso.
2) Curl the barbell up towards your shoulders by contracting the biceps. Make sure that your elbow is the only joint that is moving throughout this movement.
3) Slowly lower the weight back to your starting position.
The goal of this movement is for your elbows to be behind your body, thus focusing more on the long head of the muscle.