Stand up straight holding a barbell using a shoulder-width supinated grip (palms facing upward). Your arms should be almost fully extended, and the barbell should be resting against your thighs.
Keeping your body still, exhale as you curl the barbell up towards your shoulders until your elbows are fully flexed.
Once your elbows are fully flexed, allow your elbows to move forward a little (shoulder flexion), just until your forearms are vertical.
Hold for a count of two and squeeze your biceps.
Inhale as you slowly lower the barbell to the starting position.
Repeat for the recommended number of reps.
Comments and tips
Keep your body still. Only your arms should move.
Do not swing the barbell.
Using an EZ bar for the barbell curl can reduce the pressure on your wrists. However, the camber (bend) of the EZ bar must be minimal. The steeper the camber, the more emphasis you will place on your brachioradialis instead of your biceps.
Your biceps brachii has two heads: short (inner) and long (outer). The long head makes up the majority of your biceps peak, while the short head sits to the inner side. Using a shoulder-width (regular) grip with the barbell curl, as described above, will place approximately equal emphasis on both heads. Using a narrow grip will emphasize the long head and build the peak of your biceps. And using a wide grip will emphasize the short head and give your biceps more width. Therefore, incorporate all grips to hit the muscle from all angles.