Food for thought.

For a biceps workout to truely isolate the movement of this muscle group, you MUST isolate the upper arm to reduce collateral assistance from other muscle groups.

Therefore, the hammer curls work, but the standard barbell curl does not.

I suggest you try another movement - the biceps drag curl.

Done correctly, you will feel the effect of isolation, and should try alternating sets of suppinated and pronated grips.

My guys use this exercise, alternating it with triceps exercises twice per week.

More than twenty gymrats now employ this movement in their workouts (which vary from traditional splits to 3 day whole body / HST / and GVT variations).

In our approach, the triceps, the dominant muscle group, gets the most attention - but, the we are careful to fully isolate the biceps to help stimulate development of strength and mass.