For me, what breaks down is my lower back tightening up and causing several intents to not work as they should. Once I relax my lower back, I am able to send the incoming force down into my legs.
I know it's working because my shins and calves scream. It used to be my quads. Then it slowly worked its way down to my knees. Now it's in my calves and shins. The only other place after that is the ground.
That's where it should be going in the first place if my body would cooperate.
Lower back is a primary tension point for me . . . actually it's where it screams for me now. With practice, In a year hopefully it will have moved to my quads . . . two years, my calves and shins . . . three years, feeling into the ground . . . at some point before I die, hopefully I'll be able to move with connection.