Like the subject says, when I do bicep curls, specifically with a EZ-curl bar, I get cramping in my forearm which I feel is limiting my ability to add more weight to the bar. I get some burn in my biceps but, the cramping in my forearm is far more painful and usually is what limits my reps because I have to put the weight down and let my arm loosen up again and massage it a bit.
I've tried wider grip and close grip on the bar and both still lead to the cramping. I do weighted chin-ups and I don't get this kind of cramp.
Any explanation or tips would be greatly appreciated.