I actually don't want to know -- what I should have said is "How do YOU know what is your natural gait"??
I am willing to bet that those who are heel strikers are not in fact "natural" heel strikers -- but are simply carrying their walking gait over to running in an attempt to "go faster" .
So - how do you know what is your natural gait?? Try this -- find a nice hard flat stretch of concrete footpath . Make sure it is smooth with no pebbles sticking up -- and then run on it for a while. Heel strikers can come back and tell us if heel striking is truly their "natural "gait!!