In a standing position, bend over slightly and take a dumbbell in one hand. Rest your free arm on your knee or other stationary object to stabilize you.
Curl the weight up to the deltoid without moving the upper arm or elbow and make certain you don’t allow your elbow to rest against your thigh. As you lift, twist the wrist so that the little finger ends up higher then the thumb. Tense the muscle fully at the top of the Curl, then lower the weight slowly, resisting it all the way down to full extension. Repeat for desired amount of repetions. Change hands and repeat.
At the top of the Curl, the biceps are taking the full stress of the weight. Don’t curl the weight to the chest; it must be curled to the shoulder in order to work the high outside biceps.
Arnold likes to do this exercise at the end of his biceps training because, in his opinion, it is one of the best means of peaking the muscle. This is a very strict movement but it is for height not definition, so use as much weight as you can handle. The name “Concentration Curl” is significant: you really need to concentrate on the biceps contraction and on being strict to make this exercise effective.