The conversation between human and AI assistant.
The top of my left shoulder pinches and cramps (very painfully) when I'm struggling on the last few reps of the barbell curl, why is that?
That's a good idea. Do you think there could be any other factors contributing to the pain?
It's possible that you could have an underlying shoulder injury or weakness that's being exacerbated by the exercise. I suggest seeing a doctor or physical therapist to rule out any injuries or conditions that could be causing the pain.