Grip the handles from top pulley palms up. Stand at the middle of cable crossover machine in good body alignment (abs tight, chest up, back straight. Keep upper arms parallel to the floor and directly in line with cable. Squeeze together (retract) shoulder blades. In a controlled motion, keeping upper arms parallel to the floor, curl arms toward head. Contract biceps fully, without compromising form. While maintaining the controlled motion, return weight to starting position. Do not allow muscles to relax before next repetition.