If the shoe doesn’t fit, doctoral student can help

by Joe Carlson

Our feet have been fighting a war against mass-produced shoes since the 1700s, and a new method developed by a University researcher may help us even the odds.
Susan Sokolowski, a doctoral candidate in the Department of Design, Housing and Apparel in the College of Human Ecology, has devised a new system that will enable shoe manufacturers to create better-fitting shoes using more specific models of the human foot.
“My interest is in how people work with their equipment,” she said. Her work deals with functional apparel, such as equipment used by astronauts, soldiers and athletes, rather than ready-to-wear fashion.
Besides her four years of doctoral studies at the University, Sokolowski has a master’s degree from Cornell University in functional apparel design and human factors engineering.
There are a number of problems with the current methods used to measure and manufacture shoes, Sokolowski said, such as outdated measurements.
Currently, shoes are sized and manufactured using devices based on systems that were first developed in the 1300s, Sokolowski said.
The silver device shoe stores use to measure the length and width of customers’ feet, called a Brannock device, is based on “barleycorn technology” first developed in 1324, Sokolowski said.
In that year, King Edward II of England wanted to create a standard system of foot measurements to reduce the amount of time needed to make shoes. He ordered the largest foot he could find measured with barleycorn kernels.
England’s then-largest foot was 39 kernels long, and because three barleycorns fit into one inch, Edward divided 39 by three and decreed that the result, 13, would be the largest shoe size, and that all other sizes be measured in third-inch increments down from size 13.
Sokolowski said this system is not precise enough for most people to find a truly well-fitting shoe. Another problem is the nonlinear way feet grow.
Normally, when a particular style of shoe is made, the shape of each size is based on a single three-dimensional model, which is then replicated in the various sizes, Sokolowski said.
In reality, different parts of the human foot grow at different rates, and thus different sized feet are not simply replications of the same shape, she said.
“When you go from a small size to a large size there are some unexpected changes,” Karen LaBat, Sokolowski’s doctoral advisor, said.
“Say you’re going from a size 6 to a size 12. You might find that the toe portion does not change between a 6 and 12,” yet current shoe manufacturing methods will increase the toe portion, Sokolowski said.
But Spencer White, director of research engineering at Reebok International, Ltd., said although “there may be some trends, there is just so much variation between feet that it is hard to account for everybody.”
Sokolowski disagrees and said that there are definite trends in the rates of foot growth.
LaBat said that instead of conducting new research to account for these changes, “a lot of what’s done in sizing is handed down from generation to generation.”
Another problem with this system is that men’s and women’s feet are shaped differently, yet most shoe companies use the same three-dimensional model for both.
“A lot of the shoes started out as walking shoes for men,” Sokolowski said.
But when athletic shoe companies developed shoes designed for women in the mid-’80s, they simply used equivalent sizes of the men’s shoe model, rather than altering the proportions of the shoe to better fit the contours of the female foot.
Sokolowski’s method attempts to solve these problems by clarifying the abstract tables of data that the shapes of shoes are currently based upon, called sizing systems.
Sizing systems are tables of measurements of different parts of various foot sizes. They are inaccurate because they do not yield a true three-dimensional model, Sokolowski said.
“For example, if I told you that this woman had a 36-inch bust, a 26-inch waist, and a 36-inch hip, you really wouldn’t know what her head was in proportion to her to her bust and waist,” Sokolowski said.
“We have 13 measurements to identify a foot, but we don’t really know what it looks like” in three dimensions, she said.
Another problem with sizing systems is that most shoe companies use their own models of the foot, known in shoe-making as lasts. Thus, consumers find that they may wear different sizes depending on the brand of shoe.
Sokolowski’s method eliminates this problem by locating subjects whose feet match a sizing systems’ categories and creating three-dimensional models based on those subjects.
“The general idea of this method that I developed is that you can take any set of data in a sizing system for feet, find subjects that match those measurements and then collect data from those three-dimensional subjects,” she said. With that three-dimensional data, the manufacturers “will be able to describe their foot accurately enough to develop footwear that fits properly,” Sokolowski said.
Manufacturers “can actually see what their consumers’ foot looks like,” Sokolowski said.
LaBat said, “It’s a completely different approach to sizing systems for the body.”
Sokolowski said that initially she got the idea for the system, which currently has no formal name, from a research project with an ankle brace company called Swede-O.
The braces were tearing out in the elastic seam in the back and, working with LaBat, Sokolowski was to find out why.
“In our materials study, almost all of our subjects were female and we had many females drop out of the study because the brace did not fit their feet properly,” Sokolowski said.
“A lot of them complained of pain around the arches and a lot of them said that circulation to their feet was being cut off,” Sokolowski said.
“This brace was sized improperly for female customers,” she said.
This study led her to develop a sizing system for women, but then led her to the question, “How do you take a sizing system and match those dimensions in the sizing system and then be able to interpret that data in a three-dimensional fashion?”
The answer was Sokolowski’s new system. Currently, Sokolowski is searching for a manufacturer who might be interested in sponsoring a patent of her method.
“Our goal is to make shoes that fit the highest percentage of the population possible,” which means that individual variations may not be accommodated in a national market, White said.