Do not swing your body back as you move the weight up- this is cheating! Your body should remain straight throughout the set.
Squeeze your biceps hard at the top of the movement.
Keep your elbows tucked in at the sides, and dont allow them to come forward when curling the weight up.
Instructions
Using a close grip on the barbell curl works the outer parts of the biceps more. Grasp a straight bar with an underhand grip (palms facing up). Your hands should be about 6-8 inches apart.
Stand straight up, with your feet firmly on the floor at around shoulder width apart. You may find it more comfortable to take one foot back.
Keeping your body completely still and eyes facing forwards, slowly curl the bar up as far as possible.
Squeeze your biceps at the top of the movement, and then slowly lower the weight back down.