Today i noticed that if I hold the weight out in front of me… kind of like a preacher curl without support, I get a massive contraction that is way better than letting my arms lie limp by my sides.
I actually see what looks like my brachialis contracting separately from the rest of the biceps group when I do it.
Granted this was after 10 sets of a circuit doing 10 regular curls, 10 hammer curls, 10 arm between leg i don't remember the name curls, and 10 iso holds where I do a running motion while the arm stays bent 90 degrees… and it only happened on one side. It was still really neat to watch and feel though. At first i thought i was going to pop the muscle like a balloon. I just kept going anyway and that didn't happen. New experience.
Also i'm noticing that all those curls i did with the arm laying flat at my side put a lot more pressure on the connection at the elbow joint than the meat of the muscle.