When Kelly talks about contract and relax, does it mean to contract just the muscle/area you’re trying to change or do you contract and relax your entire body?
I take it as your entire body is completely braced like you are about to do a deadlift. And then you release that braced position.
Contract the target muscle/area.
PNF stretching involves a shortening contraction of the opposing muscle to place the target muscle on stretch. Followed by an isometric contraction of the target muscle.