I started practicing shred on my LP instead of Strat because the sound suits it more, but after a few hours on the Les Paul I get cramps in my left hand between my middle and fourth finger.

I know some people shred on Les Pauls fine, but maybe I should stay away? I've been playing strats for four years without any cramps.
you need to accustom your hand to the thickness of the LP. play it more. do more shreds so your hands would get stronger.
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