Grab a straight bar or E-Z bar attachment that is attached to the low pulley with both hands, using an underhand (palms facing up) shoulder-width grip.
Lie flat on your back on top of an exercise mat in front of the weight stack with your feet flat against the frame of the pulley machine and your legs straight.
With your arms extended and your elbows close to your body slightly bend your arms. This will be your starting position.
While keeping your upper arms stationary and the elbows close to your body, curl the bar up slowly toward your chest as you breathe out and you squeeze the biceps.
After a second squeeze at the top of the movement, slowly return to the starting position.