I seem to have done something to my left bicep. I was doing bicep curls three days ago. It was a heavier weight and I could do six reps with my right arm, but when I did one with my left I pulled the weight up once and then my bicep kind of released by itself and went totally limp.
It still doesn't really work. I can pick up light things but the muscle only flexes a little. It doesn't hurt at all. Besides feeling generally weaker, it feels normal. It didn't cramp at all, it just stopped working.
I'm 20, and have been lifting weights on and off for about 5 years.
I had a similar problem over Winter break, where my shoulder felt like it got significantly weaker. While doing pull-ups my right shoulder got tired much faster than any other muscle. It seemed to last about five weeks, and for the most part works now, though it still looks a little smaller than my left shoulder.
It is possible to have a biceps partial tear from something that simple. Our sports medicine doctor, Dr. Tom Schneider, can help sort out both your upper arm and shoulder.