Boogie Rock is an offshoot of the heavy blues rock of the late '60s. Instead of emphasizing instrumental improvisation like the original blues-rock bands (Cream, Jimi Hendrix, the Yardbirds, Led Zeppelin), boogie rockers concentrated on the groove, working a steady, choogling backbeat. Nearly every band in the style played the same 4/4 tempo — the main distinction between the groups was their instrumental attack, since some groups, like Foghat, played heavier than others.