Here's another link I tried to post that wasn't working (most of this relates to center of gravity, which is higher in lightweight trainers/trainers); greater likelihood of tipping over:http://www.reporter-archive.mcgill.ca/Rep/r3111/robbins.html
A thorn in Nike's side
DANIEL McCABE | Steve Robbins is the researcher Nike loves to hate. The feeling is pretty much mutual.
Robbins, an adjunct professor in the McGill Centre for Studies in Aging, has published studies indicating that high-priced running shoes account for 123 per cent more foot injuries than cheaper sneakers. He also aims to persuade the elderly, who enjoy the comfort of sneakers, that running shoes aren't the best choice of footwear for them.
His work has earned a fair amount of press attention and Nike doesn't much like the resulting publicity. Robbins, in turn, doesn't think much of their tactics.
More on that later.
A recent paper by Robbins, published in The Journal of the American Geriatric Society, looked at the question of seniors and sneakers.
Older people, who often have to contend with arthritic feet, appreciate shoes with thick, soft soles made of highly compressible materials.
That's why sneakers feel comfy on older feet. What the elderly don't realize, says Robbins, is that running shoes also render them far more unsteady on their feet.
This is all tied to what Robbins calls "foot position awareness." Soft-soled shoes cause "wobbling as the material compresses -- you wobble from side to side as you put weight on the material. This wobbling tends to make people lose their sense of the position of their foot in space." Our natural balancing mechanisms are thrown for a loop as a consequence.
A better choice for seniors, argues Robbins, are shoes with thinner, harder soles.
"The thicker the shoe and the softer the material, the higher the degree of instability," notes Robbins. Of sneakers, he adds, "The degree of instability that these shoes cause is truly remarkable.
"For example, a running shoe impairs measures of stability by approximately 200 to 300 per cent as compared to a hard leather shoe. That's a lot, considering that the difference between young and old people in terms of their comparable foot stability is perhaps only 30 or 40 per cent.
"We associate poor balance with older people to begin with, but what they're wearing on their feet makes a huge difference. Instability and falls are a major cause of harm in older people. Wearing the proper shoe might not only prevent fractures, it could save lives."
But do seniors have to sacrifice comfort for stability? Maybe not, says Robbins.
He realizes that older people "have a high concern for comfort" so he has been searching for a way to build a shoe that can be both cozy and secure.
He thinks he's found it.
"We discovered that the sense of comfort is basically a skin phenomenon. A softer material, even in a relatively thin layer, diffuses localized pressures on the bottom of the foot and that's what gives you a sense of higher comfort. "You don't need a thick layer. The critical layer that supplies comfort is actually the layer that is in the closest proximity to the bottom of the foot. Most of the comfort that comes from wearing a running shoe is derived from the layer that's within millimeters of the skin surface."
The next step was to find a substance that could provide extra comfort in a safely thin layer. By Robbins's estimate, he and his team tested hundreds of different materials before settling on a winner -- a substance used as underpadding on tennis courts. Robbins describes the material as low resiliency-- "that means when you compress it and then remove the weight, it stays compressed."
It feels fine on a foot. More importantly, "when we put this new material under the foot, balance actually improved by about 20 per cent over a rigid surface.
"Now, this was the first time that anything interposing between a rigid surface and the skin of the foot had actually improved balance. We noticed a statistically significant improvement in every age group that we examined."
Robbins says "it's inevitable" that somebody will seize on his research results and start producing thin-sole shoes with the material he's uncovered. But it probably won't be Nike or Reebok just yet.
"The problem is that the large shoe companies have invested heavily in products that impair balance. The customer has been sold so much on the softness of the sole and its so-called absorbing impact and how important it is. It's hard to retain any kind of market credibility by suddenly saying that everything we've been telling you for the last 20 years is bad for your health.
"Some of them may even be worried from a legal perspective. Some of [the shoes] impair balance to such a degree they might be concerned about liability."
Still, Robbins does notice thinner soles in some of the newer models of running shoes and believes his studies have something to do with it.
"I was shopping for basketball shoes for my daughter and I noticed that a whole series of shoes are becoming extremely thin soled." Robbins was pleased by the discovery.
"This notion that you need thick, soft running shoes to lower the impact on your feet is a myth. The impact can actually be greater than if you're just barefoot. When people wear [shoes that claim to absorb impact], they act differently. They run differently." People become more reckless when they think they're wearing a "super shoe."
Writing in The British Sports Medicine Journal, Robbins and his collaborators argued, "Expensive footwear is subject to extremely deceptive advertising.
"They are advertised to improve protection over cheaper products by incorporating new features that protect, and more advanced safety technology, yet epidemiological data indicate that users of more expensive shoes are injured more frequently."
Research like that prompted the marketing director of Nike to send a letter to one journal Robbins published in, claiming that Nike's own studies found Robbins's work faulty. The missive was copied to the attention of one Principal Bernard Shapiro.
Robbins viewed that as a not-so-subtle attempt to intimidate him. As for Nike's charge that his research is suspect, Robbins bristles. "My work is peer-reviewed and published in reputable journals. What they do is pseudo-science. It's there to support their marketing efforts."
Says Robbins, "I don't think [our research] is responsible for Nike's shares falling dramatically last year, but I don't think it helped them any either."
His contentious relationship with running shoe companies has made him wary of university/industry collaborations.
"I think there is an inherent conflict. The secrecy and commercial concerns you find in industry often don't allow for good scientific research. It's all the rage recently to have alliances with industry in medical research. I honestly don't think this is in the public interest.
"Just imagine if my research had been funded by the running shoe industry. What would have happened to the public dissemination of our results?"