FIELD OF DREAMS VS. HARD SCIENCE

Much is written about biomechanics. The breadth information is overwhelming and only some of it is relevant. Many conclusions presented are based on trying to sell a shoe, a book or an opportunity to be in the spotlight. Podiatry can claim partial success in staying current with the literature and leading new research. It is important to have an open mind regarding what is scientific fact in and what is folklore. Another field that has undergone an overhaul moving from conventional wisdom to applicable science is baseball. Players were rated by scouts on the basis of their looks i.e. solid chin and archaic metrics. Then a former aeronautic engineer named Eric Walker,decided to write a pamphlet that bucked against the conventional wisdom. The pamplet was implemented by the Oakland A's and is the subject of the book and movie "Moneyball". He decided to review how winning teams did based on statistical criteria that had more relevance to a player and teams success. One example:when baseball was first played players had no baseball gloves and so fielding errors measured as a statistic were an important part of the game. Now errors can actually penalize a gifted player that was fast enough to run to make a play or smart enough to be in the right spot to make a play. The statistic is less relevant to the modern game and this is how we should be viewing what we are applying in our practices. It turns out that in baseball a on base percentage is a more telling statistic of a player's intrinsic value to a team than anything else. In peeling another layer of the onion, a team's aggregate on base percentage was more indicative of success than whether one or two dominant players. Some variables are important but one must look at how the data is applied. As an example, scouts look at foot speed which is based on a timed straight run but that does not always translate precisely to running the bases, for example, rounding first for a double and the slide into second. In talking with Benno Nigg, Phd, this same philosophy becomes evident. He has been on the investigative side as a hired consultant for shoe companies before he has largely turned his focus to pure research. He is regularly interviewed in magazines like Runner's World. He is very careful not to draw conclusions that are inferences when he reviews studies. As an example when I asked him recently about a study that Dan Lieberman did on heel vs forefoot injury patterns in shod cross country runners he pointed out that you cannot compare this to barefoot running. He also pointed out that the subjects were cross country runners which does not translate exactly to everyday runners. Be careful not to jump to conclusions when the next web browser update or magazine exclaims a new finding as it may not be relevasnt.

Boimechanics:Field of Dreams Vs Hard Science

Much is written about biomechanics. The breadth information is overwhelming and only some of it is relevant. Many conclusions presented are based on trying to sell a shoe, a book or an opportunity to be in the spotlight. Podiatry can claim partial success in staying current with the literature and leading new research. It is important to have an open mind regarding what is scientific fact in and what is folklore. Another field that has undergone an overhaul moving from conventional wisdom to applicable science is baseball. Players were rated by scouts on the basis of their looks i.e. solid chin and archaic metrics. Then a former aeronautic engineer named Eric Walker,decided to write a pamphlet that bucked against the conventional wisdom. The pamplet was implemented by the Oakland A's and is the subject of the book and movie "Moneyball". He decided to review how winning teams did based on statistical criteria that had more relevance to a player and teams success. One example:when baseball was first played players had no baseball gloves and so fielding errors measured as a statistic were an important part of the game. Now errors can actually penalize a gifted player that was fast enough to run to make a play or smart enough to be in the right spot to make a play. The statistic is less relevant to the modern game and this is how we should be viewing what we are applying in our practices. It turns out that in baseball a on base percentage is a more telling statistic of a player's intrinsic value to a team than anything else. In peeling another layer of the onion, a team's aggregate on base percentage was more indicative of success than whether one or two dominant players. Some variables are important but one must look at how the data is applied. As an example, scouts look at foot speed which is based on a timed straight run but that does not always translate precisely to running the bases, for example, rounding first for a double and the slide into second. In talking with Benno Nigg, Phd, this same philosophy becomes evident. He has been on the investigative side as a hired consultant for shoe companies before he has largely turned his focus to pure research. He is regularly interviewed in magazines like Runner's World. He is very careful not to draw conclusions that are inferences when he reviews studies. As an example when I asked him recently about a study that Dan Lieberman did on heel vs forefoot injury patterns in shod cross country runners he pointed out that you cannot compare this to barefoot running. He also pointed out that the subjects were cross country runners which does not translate exactly to everyday runners. Be careful not to jump to conclusions when the next web browser update or magazine exclaims a new finding as it may not be relevasnt.

Mean Joe Green & Why We Do What We Do

If you look at how a successful company like Coke branded they did it by being everywhere. There was Mean Joe Green drinking a Coke with a kid, Coke on your kids little league baseball scoreboard etc. They established an emotional connection to the product that resulted in a more likely purchase of Coke vs another cola. In Martin Lindstrom’s book, Buyology, he explains how marketers use quantitative research, which involves surveying a large number of people about an idea, concept, or product. They then follow up with qualitative research by surveying smaller focus groups. The basic question they are trying to answer is what makes consumers choose the way they do.
​What may be surprising to discover is that many of these product surveys are not that effective. How people answer a survey is often disconnected from how they behave. One obvious problem can stem from how a survey is worded. A classic example used at Harvard Business School is a survey used to determine who would buy a Ford Edsel. The survey asked whether a potential buyer liked an Edsel, not whether they would buy it. Although most respondents liked the car, very few people actually bought an Edsel, leading to a disastrous loss for Ford.
​Lindstrom contend that we don’t always act on the answers we give on surveys because of unconscious emotions, i.e. previous childhood associations or feelings of improved status. There is a peninsula of unconscious thought that influences the way we behave. Sometimes these unconscious thoughts have a more powerful impact than the conscious answers we give when filling out a survey. ​
​For example, a customer with a foot injury walks into a running store and is met by a young dynamic salesperson who fits the customer with a running shoe selected to help him with his injury. The customer then decides to have a gait evaluation and get information about his stride.
The impulse to get the gait evaluation was borne of both emotion and convenience.  What that customer does not realize is that he may have some condition, such as a leg length discrepancy, that warrants a medical professional’s attention. How we make decisions turns out to be tied to the emotional connections associated with the choices as much as anything else.

What Do Planes, Diabetics and Athletes Have in Common? Shear Force: The Common Dilemma that Diabetics and Athletes Face

For years the biomechanics community has been talking about pressure as a leading cause for ulcers, while its counterpart, shearing, was generally left out of the discussion. It turns out that the same force that causes blisters in runners may be the key to unlocking ulcer prevention.

What Does the Research Show?

Dr. Bijan Najafi at the Center for Lower Extremity ambulatory Research (CLEAR) in Chicago sums it up this way: The most dangerous period for a moving body is during gait initiation and termination because this is when the body is most subject to accelerating and decelerating forces. The same principal holds when considering an airplane taking off and landing. The greatest risk for a crash is during takeoff and landing, during which the plane must endure significant stress from the extreme accelerations and decelerations. Just as a plane reaches a steady state at its cruising altitude, people achieve a steady state during episodes of walking. Individuals with diabetic neuropathy take particularly long to reach a smooth walking gait. It typically takes over 4 steps for a diabetic with moderate neuropathy to reach steady state according to Dr. Najafi, which is in average 25% higher than healthy control subjects. Depending on the type of footwear or insole, this number could be increased or decreased. Although four steps may seem like a small number, when we look at it in the context of daily physical activity it becomes very important. A recent CLEAR study published in Diabetes Care revealed that diabetic patients initiated over 350 episodes of walking per day that are often short (less than 20 steps per episode). The 2010 Diabetes Care study noted that diabetics average 7,800 steps per day, and an average of 10-15 steps per episode of walking.


Various methods have been proposed to decrease shearing in shoes including the use of roller soles, bilayer insoles and orthotics, socks and skin lubricants. Dr. David Armstrong feels that traditional plastizote will eventually become passe in favor of emerging superior biomechanical products.

Brian Davis, PhD, has stated previously that one should not overlook shearing forces when noting the moderate success of therapeutic footwear. While it is likely frictional forces are a key variable, he acknowledges several other reasons for skin breakdown. These factors include alterations in collagen properties, autonomic nervous dysfunction that alters sweating responses, diminished microcirculation and superimposed aging. Hydration also cannot be ignored. Good skin turgor depends on proper hydration.

Dr. Najafi feels that there are some misconceptions regarding research on efficiency and friction. In some lab testing, the emphasis has been on the shoe ground interface instead of the foot shoe interface. But, currently this is a serious challenge, since there is no available technology to measure the shearing inside of shoes. An alternative solution is measuring the effect of reducing shearing on the biomechanics of walking. For example, if we could reduce shear force between the foot/shoe interface but not on the shoe/ground interface, this would allow us to increase the distance between center of pressure (COP) and center of mass (COM) in particular during gait initiation, which in turn would increase gait initiation velocity. Biomechanically, this is similar to a runner who tries to increase his take off velocity by leaning forward. Najafi’s recent study confirmed this hypothesis, in which significant improvement was noted in gait initiation velocity by wearing insoles that reduce shearing compared to sham insoles. He also notes that orthotics reduce the number of steps required to reach steady state. Reducing shear force does not reduce gait velocity.

He notes we should be careful about the balance of our patients, since increasing the distance between COP and COM may trigger falls in those patients with poor muscle performance. Therefore, an assessment of a patient’s balance and risk of falling is of key importance after reducing any shearing on the foot/shoe interface.

In the pipeline, Dr. Najafi is exploring differences in people with diabetic neuropathy versus healthy age matched controls under both shod and barefoot conditions. Gait parameters such as stability and gait fluctuation will be assessed.

How Can We Incorporate These Anti-shearing Methods in Our Practice?

Currently, there are ongoing investigations on various types of innovations in arch supports and orthotics. Lubricant creams are also under current study. Socks that have better wicking properties are something that we should be recommending to both runners and diabetics alike. It remains to be seen whether some of the double layer socks provide any therapeutic benefit over single layer socks. Some running store owners I interviewed related that some runners report bunching with some of the double layered socks.

It appears that a combination of following the research and clinical experience will guide us toward the best solutions for this issue.


References:
David Armstrong, DPM. Personal Communication. 2011.
Davis, Brian. “Can Smart Orthotics Have An Impact in Preventing Diabetic Ulcerations?”. Podiatry Today. Volume 23. Issue 6. June 2010.
Bijan Najafi, PhD MS. Personal Communication. 2011.
Najafi, Bijan. “Importance of Time Spent Standing for Those at Risk of Diabetic Foot Ulceration”. Diabetes Care. Volume 33. Number 11. November 2010.