Seated Dumbbell Concentration Curls
A variation on the standing dumbbell curls, this one relly strives to isolate the biceps even further. This is more of an isolation exercise in that it primarily hits the bicep muscle.
Sit at the end of a bench resting your elbow on the inside of your thigh, as in the picture. Exercise only one arm at a time, and rest the other arm on your leg, either free or for support. Slowly curl the weight up and down at the same speed. Concentrate and contract intensely on the bicep as you curl the weight upward. After training one arm, switch and immediately do the other arm in the same fasion for an identical number of reps.