Almost every time I do fairly heavy lat pulldowns/inverted rows/chins etc, my left elbow 'locks' near the point of full extension and get a sharp pain. I have noticed however, that when performing inverted rows the problem doesn't occur with a pronated grip whereas it does with supinated. I only experience this in my left elbow (I'm right-handed so it's unlikely to be an overuse injury) and also take Glucosamine Sluphate and fairly high doses of fish oil each day (about 2g). Does anyone else have this problem or know what might be causing it? Thank you!