From Born to Run by Christopher McDougall:
"Running shoes may be the most destructive force to ever hit the human foot. ... Consider these words by Dr. Daniel Lieberman, a professor of biological anthropology at Harvard University: 'A lot of foot and knee injuries that are currently plaguing us are actually caused by people running with shoes that actually make our feet weak, cause us to over-pronate, give us knee problems. Until 1972, when the modem athletic shoe was invented by Nike, people
ran in very thin-soled shoes, had strong feet, and had much lower incidence of knee injuries.' ...
"We've shielded our feet from their natural position by providing more and more support," [Stanford track head coach Vin] Lananna insisted. That's why he made sure his runners always did part of their workouts in bare feet on the track's infield. ... 'I think you try to do all these corrective things with shoes and you overcompensate. You fix things that don't need fixing. If you strengthen the foot by going barefoot, I think you reduce the risk of Achilles and knee and plantar fascia problems.'
" 'Risk' isn't quite the right term; it's more like 'dead certainty.' Every year, anywhere from 65 to 80 percent of all runners suffer an injury. That's nearly every runner, every single year. No matter who you are, no matter how much you run, your odds of getting hurt are the same. It doesn't matter if you're male or female, fast or slow, pudgy or ripped as a racehorse, your feet are still in the danger zone. Maybe you'll beat the odds if you stretch like a swami? Nope. In a 1993 study of Dutch athletes published in The American Journal of Sports Medicine, one group of runners was taught how to warm up and stretch while a second group received no 'injury prevention' coaching. Their injury rates? Identical. Stretching came out even worse in a follow-up study performed the following year at the University of Hawaii; it found that runners who stretched were 33 percent more likely to get hurt. ...
"In fact, there's no evidence that running shoes are any help at all in injury prevention. ... Runners wearing top-of-the-line shoes are 123 percent more likely to get injured than runners in cheap shoes, according to a study led by Bernard Marti, M.D., a preventative-medicine specialist at Switzerland's University of Bern. ...
" 'The deconditioned musculature of the foot is the greatest issue leading to injury, and we've allowed our feet to become badly deconditioned over the past twenty-five years,' [the Irish physical therapist] Dr. Gerard Hartmann said. ... 'Putting your feet in shoes is similar to putting them in a plaster cast,' Dr. Hartmann said. 'If I put your leg in plaster, we'll find forty to sixty percent atrophy of the musculature within six weeks. Something similar happens to your feet when they're encased in shoes.' When shoes are doing the work, tendons stiffen and muscles shrivel. Feet live for a fight and thrive under pressure; let them laze around, as [miler] Alan Webb discovered, and they'll collapse. Work them out, and they'll arc up like a rainbow. ...
"[The change began in 1962 when Nike co-founder Bill Bowerman created] the most cushioned running shoe ever created - the Cortez. ... Bowerman's deftest move was advocating a new style of running that was only possible in his new style of shoe. The Cortez allowed people to run in a way no human safely could before: by landing on their bony heels. Before the invention of a cushioned shoe, runners through the ages had identical form: Jesse Owens, Roger Bannister, Frank Shorter, and even Emil Zatopek all ran with backs straight, knees bent, feet scratching back under their hips. They had no choice: the only shock absorption came from the compression of their legs and their thick pad of midfoot fat. ...
"But Bowerman had an idea: maybe you could grab a little extra distance if you stepped ahead of your center of gravity. Stick a chunk of rubber under the heel, he mused, and you could straighten your leg, land on your heel, and lengthen your stride. ... He believed a 'heel-to-toe' stride would be 'the least tiring over long distances.' If you've got the shoe for it."