Normal, weak or not depends on how long you have trained, your
body mass, your limits and etc.
A good gauge for me is to push myself to the very limit and make
sure i can't raise my arms above my shoulder after training.
Point is to tear your muscle as much as you can, so that when your
body repairs the micro tears, you will gain muscle mass.
and don't jump around weights. Just keep to 85% of your 1-rep
weight. And re-evaluate your 1-rep weight every once in a
while.
