I found this by Maffetone (one of the founding fathers of modern endurance training):
Is the Right Shoe on Your Foot?
(Reprinted with permission from "In Fitness and in Health" by Dr. Philip Maffetone)
Our modern, media-driven society encourages companies to sell products based on their special features, even if those features are not necessarily beneficial. One example is the shoe companies that make athletic or exercise footwear.
They used to be called sneakers back in the good old days; these days they have all kinds of names and specialties and all sorts of features. You've heard them all: energy return, pronation support, supinator shoes, heel stabilization, motion control. They're made with gel, rubber, molded EVA and pumped with air. Companies insist they spend a lot of money to research a shoe, but what they don't say is that the research goes into marketing and promotion strategies, and how to sell you yet another shoe for $100 or more.
For the most part, shoes are tested on machines, not people, because machines give the results the company wants and people don't. A quick look in the medical journals will point out the abundant problems.
Did you know, for example, that the support systems in almost all shoes can weaken your ankles? And the soft, cushioned shoes of today can harm your feet? How about the height, in other words, the thickness of the sole? The farther above the ground you go in a shoe, the more unstable your foot becomes.
Scientific articles over the past decade or more strongly suggest that such protective features put in by shoe companies, including shock absorption and motion control actually increase the likelihood of injury.
Here are some of the reasons.
The human foot has millions of nerves endings, especially on the sole, which senses the pounding and repetition of running, dancing, walking or other activity. Your brain and body work together to adapt to the stress of hitting the ground by adjusting the gait. This normal protective mechanism (which occurs constantly, and not just from the feet but also most parts of the body, including the joints) keeps us from being injured during activity. When we put a sneaker or shoe on the foot, we interfere with the body's normal adaptive mechanism. The mechanism works best when we walk or run barefoot because there is no interference with the nerves that sense our contacts with the ground. In other words, footwear can mask the sensations of activity, preventing the body from adjusting itself to perform better. The thicker and more overprotected the shoe, the worse it is for the body. The impact which results from exercise occurs whether a shoe is worn or not. Some studies show that many materials used in the fancy exercise shoes alter and distort sensation enough to actually increase the impact on the ground!
The result is a diminished ability by the foot to adapt, with potential damage to the ligaments, fascia, cartilage or bone in the foot, leg or pelvis.
A significant aspect of natural foot mechanics is the function of the medial arch. This natural support, maintained by a muscle, adapts constantly to standing, walking, running, etc. Many shoe support systems, including orthotics, can interfere with this normal functioning arch.
Sorbothane is commonly used in athletic shoes. Tests on machines show its energy absorbing abilities. But a study on humans shows that insoles made of this material actually increase leg stress by 26%. Another study failed to show any beneficial effects, but clearly demonstrated that the subjects used (U.S. Marines) had an increase in foot and leg injuries.
Other studies show similar patterns. In one, among 5,000 runners, those using more expensive running shoes (which had more shock absorbing materials) had a higher incidence of injury. Clearly, there is less chance of getting a running injury in less expensive shoes.
Pronation is a common concern among exercisers. A certain amount of pronation is normal; excess pronation can be a problem. But the more shoe manufacturers cushion the foot, the more likely the foot will prorate excessively, especially with the added soft midsole material. Shoes claiming to control pronation may actually aggravate it. Heel height can also increase pronation, especially when higher than about one inch.
Don't pay attention to claims that an exercise shoe will make you perform better. Data shows that running, for example, in a well cushioned shoe will slow you down. That's because these shoes cost more than money; they cost you in oxygen, too. The thicker, more energy absorbent athletic shoes require significantly increased oxygen uptake. It's due to the increased contact time the shoe is on the ground and the reflex leg muscle activity.
What Can You Do?
Many people have gotten "addicted" to their shoes. The same problem exists for some women who have worn high heels for years. The muscles of the foot and leg, especially the calf, have adapted to the shoe. If you suddenly change your shoe style, such as a lower heel, your muscles will have to readjust their length. This will take some time, often a couple of weeks, during which you may experience calf pain or other discomfort.
Case history
Some time ago, after seeing running shoes get higher off the ground, over supported and softer, I thought about the times in college when I ran barefoot. From a practical standpoint, I wasn't willing to go that far, so I looked for the closest thing: a shoe that didn't restrict my natural foot and ankle mechanics but offered protection from stones and wear and tear. I started by looking at the newest shoes but was immediately horrified at the prices. The so-called racing shoes looked better for everyday use, not as much over support and cushioning, and lower to the ground, but still over priced. I tried Keds. Yes, those cheap no-attempt-at-support sneakers. For under $10, I was on my way. But my first day running left my calves quite sore. I realized it was just the difference in heel height, coming down to the ground from what seemed like stilts. The second day out, my legs wouldn't let me run. Even walking was uncomfortable. I found walking on the treadmill acceptable to my body. After a week of that, and feeling better, I began running on the treadmill. And after another week, ventured outside again. My calves and everything else adapted to the somewhat radical change in shoes and felt like those of a 20 year old elite athlete.
The typical heel in exercise shoes forces you to run too far back on the shoe rather than striking the ground farther forward. This exaggerated heel-toe gait is a walking style and is unhealthy for runners.
Shoe companies allude to magical abilities possessed by the shoes in advertising: this shoe cures weak ankles, these shoes correct pronation and that shoe makes you run faster. To make things worse, you have to pay dearly for the advertising and the high-tech additions to your shoes which may have an adverse effect on your health.
Correction
Treating any footwear problem involves, mainly, knowing how to select the proper shoe. You may also need to seek help from a competent professional who can correct any mechanical problem which may exist.