no matter how much weight i put on it feels like it isnt doing anything... right now i have 100lbs on a bar and im like ;\ ok .. it only starts to feel effecting on the last 2-3 reps of the last set of 10 (3 sets). i was wondering, if i goto a gym and do shrugs on a smith machine would people get mad? or what.... i just wanna see how much weight i can go up to...