In interviews, George Lynch says he gets that same thing from the way he holds his guitar pick, too. He said he puts something called (I think) Nu Skin on the finger, which must be some sort of skin patch, to get him thru the next gig.
If you're trying to build up speed - alternate picking works better for me when I'm letting more of the pick stick out and holding it straight up and down, rather than the tilted position I used to hold it in. Sweep picking's a whole 'nother matter, though.
"Jimi would be playing an HM Strat if he were still alive." Bob @ Genesis Recording Studios.