Materials: Do soft soles improve running shoes ?

April 1998
Do soft soles improve running shoes?
Most athletic shoes advertise injury protectiong through “cushioning,” but real world studies have not shown impact moderation.
By Steven Robbins, MD, Edward Waked, PhD, and Gad Saad, PhD

here are their conclusions word for word:

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“Shoes with cushioning fail to absorb impact when humans run and jump, and amplify force under certain conditions, because soft materials used as interfaces between the foot and support surface elicit a predictable reduction in impact-moderating behavior.5-10,13-17 This behavior is not a response to sensations directly caused by impact because, whereas barefoot humans estimate impact precisely, humans judge it inaccurately when shod.14-17 This situation has recently been made clearer. Reduction of impact-moderating behavior is a response to loss of stability induced by soft-soled cushioned shoes: Humans reduce impact-moderating behavior in direct relation to increased instability.27 This is presumably an attempt to achieve equilibrium by obtaining a stable, rigid support base through compression of sole materials.27
After considering footwear advertising, additional factors appear to influence impact-moderating behavior. Recent reports also indicate that humans reduce impact-moderating behavior, thereby amplifying impact, when they are convinced that they are well protected by the footwear they are wearing. Advertising that suggests good protection results in higher impact, whereas advertising that suggests injury risk attenuates impact.19 Deceptive advertising, suggesting that expensive cushioned footwear offers advanced technology that protects against impact, accounts for the 123% greater frequency of injuries with the most expensive shoes found by Marti.18
Public health could be advanced through truth in advertising of footwear products with cushioned soles. Furthermore, footwear must be required to provide good balance. Current athletic footwear undoubtedly causes falls, since footwear with thick yielding soles destabilizes humans by as much as 300% compared with hard-soled shoes.
Now that the destabilizing nature of cushioned footwear is well established, continued manufacture of these hazardous items without explicit warning labels represents risk for liability claims from users who are injured from falls and ankle sprains while wearing them. In the context of this report, footwear that provides superior balance will probably be effective at attenuating vertical impact. Clearly, highly resilient materials must be removed from shoe soles for many reasons. This move will portend better health through improved stability and fewer injuries from excessive repetitive impact in sports. ”