Is it easy to strain muscles?

[ANARKY]

I partial tore my left bicep when I was 14 and I'm 22 now and last night at the gym I was doing behind the back traps with the smith machine and I had 315lbs on it which is alot for me and after I got done my left arm was pretty sore, no bruising so I don't think anything is torn just sore. I was just wondering is it pretty easy to strain a muscle like this?

[Casey]

It shouldn't be. Although once you've pulled or damaged a part of your body once, its often more suseptable to it again. But if your streatching good, and keeping good positioning you should be fine. Your left arm could also be sore because it could be weaker then you right arm, I got the same problem. My right arm rarly gets sore, only my left. (Somtimes a bit too sore)