A groove is not a set of limbs. A groove is a set of parts — a hat part, a snare part, a kick part — and the choice of which limb plays which part is a separate decision. Move the hi-hat 8ths from your hand to your foot and the texture lightens. Move a kick figure to the snare and the same rhythm becomes a different groove. Move a snare comp to the kick and you have an entirely new feel.
This is what serious players mean by independence: not "I can move my left foot freely" but "I can put any part on any limb." Every great drummer can take the same notated groove and play it three or four ways without changing what reaches the listener.
The exercises below take a single backbeat and orchestrate it three ways: hat in hand (the standard), hat in foot (lightened), hat split between hand and foot (the linear style). Same notes hit the air; different limbs do the work.
Exercises
The standard backbeat: hi-hat 8ths in the strong hand, snare on 2 and 4, kick on 1 and 3. Memorize how it feels physically — which limb is doing what at each beat. The next two exercises will redistribute these same parts across different limbs.
Same groove, completely different orchestration. The hi-hat 8ths are now in the FOOT (notated on the hat-foot line); the kick still plays 1 and 3 (chorded with the foot-hat on those beats); the snare still plays 2 and 4 in the hand. Tempo dropped because eight hat-foot 8ths per bar is hard. The listener hears the same groove; your body distributes the work differently. This is the basic substitution principle.
Hi-hat 8ths split: hand on the downbeats (1, 2, 3, 4), hat-foot on the offbeats (&'s). Together they sum to the same continuous 8ths, but each limb only plays half. This is the linear coordination style — no two limbs hit at exactly the same instant on the offbeats. The kick on 1 and 3 chords with the hand-hat; the snare on 2 and 4 chords with the hand-hat. Same groove, third orchestration.
Compare to Ex 1. The kick used to fall on the & of 3 as a syncopation; now play that hit on the snare instead — as a ghost-note-flavored snare. The rhythm of the bar is unchanged, but the texture redistributes: the kick stays on 1 and 3, the snare picks up the syncopation that used to be a kick. Same notes hit the air; different drum produces them. Substitution doesn't have to be foot↔hand — it can be drum↔drum.