For the last 6 months or so, I've been constantly pulling my left bicep muscle. I workout regularly to stay in shape for enduro racing, but I've only been lifting heavy weight and trying to bulk up for about a year. I don't overdo it in the gym in my own estimation, but that probably means nothing. The strange thing is that I never pull my bicep while lifting weights. It's always doing something light or stupid, or when we were moving over the summer. Lifting an oil can, picking up my gear bag to go ride dirt bikes, hoisting a fuel can into the truck. And because it's never from lifting heavy stuff, I can never anticipate when I will pull the muscle again. Aside from stretching and warming up, trying not to lift too much, what can be done to prevent this issue from continuing? Quit lifting weights for a month to see if that fixes it?