Thursday, October 25, 2007

More thoughts on shoes - Foot Injuries

The post a few days ago on shoes caused little bit of discussion in the comments and also on the Ironworks board.

I came across this article on the website of the conditioning coach Vern Gambetta.

Materials: Do soft soles improve running shoes?
Most athletic shoes advertise injury protection through “cushioning,” but real world
studies have not shown impact moderation.

There is a stark claim here that the problem includes deceptive advertising and the danger that expensive shoes actually cause injury.

You should read the whole article but the conclusion is worth pondering:

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 behaviour.

This behaviour is not a response to sensations directly caused by impact because, whereas barefoot humans estimate impact precisely, humans judge it inaccurately when shod. This situation has recently been made clearer. Reduction of impact-moderating behaviour is a response to loss of stability induced by soft-soled cushioned shoes: Humans reduce impact-moderating behaviour in direct relation to increased instability. This is presumably an attempt to achieve equilibrium by obtaining a stable, rigid support base through compression of sole materials.

After considering footwear advertising, additional factors appear to influence impact-moderating behaviour. Recent reports also indicate that humans reduce impact-moderating behaviour, 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.

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.

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. Steven Robbins, MD, and Edward Waked, PhD

Maffetone has made the same points for years: Is the Right Shoe on Your Foot?

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.


Bryce said...

The thing about not sensing impact correctly really rings the bell of truth.

I was having a phone conversation just a few hours ago about kinaestheic awareness and how it isn't just a "sense" but actually an entire sense/ feedback/correction system which if purposefully given bad information makes people do funny and self destructive things.

I'm remembering how some old cars just floated down the road and gave you this feeling of just flying softly on a bed of clouds, then you tried to hit the brakes or turn and realized how close to the truth that really was.


Chris said...

Squashy brakes and soft suspension....I remember those cars.

I read some of this in Phil Maffetone's book "Fixing your Feet" a few years ago but this has reminded me of things I'd not been thinking about.

The advertising thing is huge too. It is the same with sports drinks - the research is either not in favour or if it is you find that it is funded by Gatorade or Lucozade.