When i hear good shredding and sweeps, its hard to hear what type of patterns they r using. to start off, i know good shredding patterns, but i cant seem to play them fast enough, and i am alternate picking. I cant seem to connect fast alternate picking w/ the patterns. Is there a trick or do u just need practice?

reguarding sweeps....ive seen it done, but the picking sequence is hard to distinguish. r u supposed to alternate pick those, or is it just a sweeping motion w/ extrememly fast fingering....someone help me out, thanks