For more Martin Goulding videos, check out http://martingoulding.com The following content is related to the March 2012 issue of Guitar World. For the full range of interviews, features, tabs and more, pick up the issue in our online store. Thrash developed in the early Eighties as a subgenre of the broader heavy metal category and gained momentum throughout the decade. From the pioneering "Big Four" bands—Metallica, Megadeth, Slayer and Anthrax—to Exodus, Testament, Overkill and Sepultura, thrash metal pushed the boundaries of aggression, speed and stamina with fast, muted open-string-based riffs and furious lead breaks.