Ok, I've been doing pinch grips once a week (not with much weight as I've only just started and can't handle much yet), and usually everything is fine with them. However, I sometimes find I get a sharp pain from my right thumb just from holding them (it starts immediately). I think it's where the side of my thumb's knuckle is pushing against the plate. It makes my thumb start to go numb and I simply cannot hold on to the plates. The more I try to hold on the worse the pain gets. Has anyone else had this problem? Any ideas? Am I doing something horribly wrong? Cheers.