"The first exercise in any biceps-repertoire has to be the standing barbell curl. Many people advocate you do this with an EZ-curl bar, to save the wrists and put the hands into a more ergonomically correct position. Bullshit I say. By doing this you bring the hands into more of a hammer grip which shifts the focus outwards more. To do a correct barbell curl you need a straight bar because this will twist the hands in in the point of contraction and ensure more fiber is stimulated in the inner head. Since the inner head is the bulk of the biceps this makes perfect sense. Whichever way you do it (you may not wish to accentuate the inner head and opt for the EZ way out) you'll need to be standing straight up and stay that way throughout the movement. The barbell should be held shoulder-width apart and resting comfortably against the upper legs. Your elbows are by your side. Your hands face forward naturally. As yopu curl the weight up you have to watch two things. The first is that you keep the elbows pinned to the side and that they under no circumstances move behind the body which takes the pressure off and involves the traps and lats. The second thing to watch is that your back stays straight, it shouldn't move forward or backward to create a more advantageous position. If you find that you cannot avoid this, you are using too much weight. If need be stand against a wall and make sure you keep your back against it. I'd like to think you have enough self-control to manage it without the wall. Curl the weight up as far as you can, then and only then let the elbows move forward to create an even bigger contraction, hold for a count, lower the elbows to the side and then lower the arms gently so you feel the negative portion of the exercise. Elbows should never flare out and when you move them forward be sure that the forearms never reach a perpendicular position which will take pressure off as well."
straight out of one of Big Cat's training articles.... i believe he is right. I find barbel curls give me a much better work out than EZ bar curls.