its all about polyrhythms and limb independance, grind blasts are an excellent way to coordinate your double bass, for every single straight (not shuffling 'monkey' blast) blast note you play with both arms hit each pedal independently

1 2 3 4 1 2 3..
S S S S S S S left hand
C C C C C C C right hand
lf rf lf rf lf rf lf feet

excellent blast and feet independence exercise!