Illusions! It is not uncommon for there to be the appearance of heel striking but in reality the heel is only touching the ground slightly before the midfoot and most all of the impact is absorbed through the midfoot. Watch people run on the treadmill next time you are at the gym. You will notice that most people crash their heel into the treadmill and then roll forward but you will notice some that appear to heel strike but actually land midfoot. I don't mind people heel striking, what bothers me is people who run up on their tippy toes!