Biceps... To peak or not to peak

A guys comes up to me the other day in the gym and asks me for an exercise he could do for his biceps.
Now this guy has great arms. You can see he has a lot of muscle development, but he has no peaks on his biceps. They were big, but no peaks.
I asked him does he curl with his fist bent forward like the above picture or does he curl with his fist bend back, like the bottom picture...


He told me he has never curled with his fist bent back. I mentioned to him, by curling with your fist curled forward you involve more forearms (he has great big forearms) and you are not fully contracting the biceps as much as you could.
For me, I've always tried to isolate the muscle I'm working on as much as possible.
By bending my fist back and leading with my wrist during a bicep curl, not only am I isolating my biceps from my forearms as much as possible, I'm also enabling a much greater contraction and developing a nice peak.

This all leads me to this conclusion... it's not all of one way or no way, it's variety and being able to change to make changes. Just the little wrist change can make a difference in your muscle development and how that exercise shapes you.
I have been trying to get my forearms to catch up to my biceps my whole life... last night I curled with my fist curl forward towards me, like the above picture and my forearms got a great pump! Sometimes change is a good thing...

Time for a protein drink