Thread: Curls

I know this sounds dumb, but can someone explain how or why one movement feels like works more then others....like when I do straight bar curls I don't feel like I isolate my bi very well. But when I do the same with EZ curl bar I do....same goes for dumbell curls....if I keep my palms up I don't feel it as much as if I curl my hands to be palm in at the bottom and twist on the way up....when I twist on the way up it feels like I get a better pump and a tighter contraction of the muscle vs just keeping my palms up the whole time....anyone?

changing hand position changes the mechanical advantage of muscles, which changes the tension that can be developed.