Lie down on a bench on your back. With your arms fully extended at a 90-degree angle to your body, grip a barbell or curl bar with your hands no more than 6-8 inches apart. Keeping your arms locked at the shoulder, lower the bar toward your head bending only at the elbow. Keep your elbows in tight and pointed down toward your toes. The bar should be lowered until it nearly touches your head in between the eyes and the top of your forehead. Then, using only your triceps, drive the bar back to the starting position, again only moving your arms at the elbow and locked at the shoulder.