Note that the foot is hyperpronated at heel contact and midstance (abnormal pronation increases from heel contact through heel lift at which time foot enters the windlass mechanics and abnormal pronation is attenuated).
This is an example of gravity drive engaging at heel contact (in order to bring the entire supinatus heel bone surface in contact with the ground) and continuing through foot flat and midstance in order to bring the elevated first metatarsal/hallux to the ground.
