Hello fellow fitness blades, I've a question for those of you educated in anatomy, lifting, and the like. I've had this strange thing going on as long as I can remember - my right trapezius muscle, Trapezius muscle - Wikipedia, the free encyclopedia, will not flex. When I do shrugs, I can do the same amount on each side, but when I flex my left one, I am unable to flex the right one and make it 'pop up' for lack of a better term. The only thing I can think of that would cause this is the fact that I used to play baseball, and had poor form in my throwing arm (right arm) for several years. When I attempt to flex, both shoulders move down towards my torso, my left trapezius 'pops up', but the right shoulder drops more than the other, and the trap on that side doesn't bulge, at all. the short of it: right trap won't flex Thoughts? edit: In a similar vein, what is the best way to improve asymmetrical muscles? My left side is deficient to my right as far as size goes, but equally strong.