Select the appropriate weight matching your type of training and your fitness level. Take a shoulder-width stance. Grab the bar with an underhand shoulder-width grip (radial sides facing outward, palms upwards).
Curl the weights forward while bending your elbows; continue until the bar is at shoulder level. The elbows remain close to your torso all the way through. Go back to the starting position in the same way. Breathe out as you go up and breathe in as you go down to the starting position.
Make sure to maintain correct stance and bar grip. Avoid excessive elbow motion in the sagittal (front-rear) axis and undesirable dorsal wrist flexion. Maintain the correct stance without bending your back backwards (lumbar lordosis).
Watch yourself in the mirror to maintain the correct stance in all stages of your motion.
To acquire better control and correct stance, you can start this exercise by leaning against a wall to avoid excessive elbow movement and rocking.
EZ bar is easier to handle than “regular” straight bars. The main advantage of EZ bar is that the hands are in much more natural position. Straight bar will sooner or later start hurting your wrist and possibly elbows – it is more or less just a question of weight.
Some athletes shun the EZ bar because it takes off some weight from biceps and puts more pressure on brachioradialis muscle. This is obviously a question of your training plan but a well-developed brachioradialis muscle doesn’t seem to us to be a big handicap in bodybuilding…
Do not cheat in first repetitions. Try to do the movement slowly; you can apply some cheating in the last two reps.