I use barbells for almost all my excercises, yesterday at the gym i decided to do some alternating curls because ive been using the e-z bar for months now. i use 100 for curls so i figured i could maybe use 50's ..but i coudnt . I tried the 45 's with the same result, so i grabed the 40's and could barely get out 5 reps..it was kinda disconcerting. is it normal to a have a strength deficet between dumbell and barbell weight?