Here’s more on the 100 Up running exercise that the New York Times Magazine discussed. The video below is helpful to see what the proper technique is.
The 100 Up exercise, which McDougall is touting as a surefire technique for training away these bad habits, is actually an incredibly old invention of a long dead English chemist apprentice. Since he was English, in this case being a chemist probably refers to a pharmacist. W.S. George developed his exercise pattern so that he could train for running even while busy at work all day. The technique was apparently quite successful, as George went on to achieve world record times in several short and middle distance races.
via The 100 Up Exercise: Method for Training Barefoot Running Form | Naturally Engineered.