Every year, 20 billion pairs of shoes are sold globally, ranging from athletic sneakers to formal shoes and work boots. Yet, despite the variety in style, the industry continues to rely on outdated sizing systems based solely on length and width. This two-dimensional approach ignores the complexities of human feet, leaving 63–72% of people wearing ill-fitting shoes (Buldt & Menz, 2018). Poorly fitted footwear not only affects comfort but also has far-reaching consequences for health and quality of life. To address this widespread issue, we must understand its origins and the obstacles that persist.
The Complexity of the Human Foot
The foot is one of the most intricate parts of the human body, consisting of 26 bones, 33 joints, and over 100 muscles, tendons, and ligaments, along with an intricate network of nerves and blood vessels (Goonetilleke, 2013). These structures absorb up to three times our body weight with every step, providing balance, agility, and shock absorption (Saltzman & Nawoczenski, 1995; Farris et al., 2016).
However, feet are far from static. Contrary to popular belief, they continue to grow and change throughout life due to factors such as aging, pregnancy, weight gain, and genetic predispositions (Harvard Health, 2018; Marks & Morrison, 2019). Over time, the fat pads that cushion our feet wear down, and ligaments loosen, causing feet to grow wider and longer (Health Essentials, 2020).
Even collectively, human feet are evolving. Average shoe sizes in the U.S. have increased by nearly an inch since the 1970s, driven by factors like better healthcare, processed foods, and rising obesity rates (Holmes, 2014; Pollak, 2012). Yet, shoe design has not kept pace with these changes, leaving a gap between what customers need and what the industry provides.
Shoe Lasts and the Fit Crisis
Shoemaking starts with the creation of a "last," a three-dimensional mold around which shoes are constructed. Historically, lasts were crafted to accommodate a variety of widths and lengths, but mass production and globalization have simplified this process at the expense of fit (Chen, 1993). By the 1970s, most brands reduced their sizing options to a single standard width per length (Alpert, 2021). Today, 99% of shoes sold in the U.S. are imported, with manufacturing concentrated in regions like China and Vietnam (Selyukh, 2019).
This shift to offshore, mass production has created a supply chain that is slow to adapt. Despite the rise in average shoe sizes, manufacturers continue to produce limited size ranges, and retailers are hesitant to stock larger sizes (Trice, 2014). This results in a Catch-22: without diverse sizing options, it's difficult for brands to gather data on customer needs, hindering innovation and perpetuating poor fit (Alpert, 2021).
Why Fit Standards Fall Short
Even with perfect data on foot dimensions, current sizing frameworks are flawed. Most shoe sizes are based on the dimensions of the last rather than the foot itself. This creates variability in how shoes fit, as factors like toe allowance, material, and design influence the "effective length" of the shoe (Bayes, 2020).
In the 1970s, SATRA proposed Mondopoint, a sizing system based on foot dimensions rather than shoe molds. While Mondopoint has the potential to revolutionize the industry, it requires alignment across manufacturers, retailers, and consumers—a significant barrier to adoption (Bayes, 2020).
Toward a Future of Better Fit
The footwear industry's fit crisis impacts not only individual comfort but also long-term health, business profitability, and environmental sustainability. As Natacha Alpert, a leader in 3D scanning and footwear design, notes, "We are in a new era where fit, customization, and comfort are increasingly valued as priorities" (Alpert, 2021). Emerging technologies like 3D scanning and generative design tools are paving the way for a future where shoes are tailored to each individual's needs.
Sources
- Buldt, Andrew, and Hylton Menz. “Incorrectly fitted footwear, foot pain and foot disorders: a systematic search and narrative review of the literature.” Journal of Foot and Ankle Research. Volume 11, Issue 43 (2018). Read more.
- Goonetilleke, Ravindra S. The Science of Footwear. Boca Raton: CRC Press; 2013, pp. 3–4.
- Saltzman, Charles L., and Deborah A. Nawoczenski. “Complexities of Foot Architecture as a Base of Support.” Journal of Orthopaedic & Sports Physical Therapy. Vol. 21, No. 6, pp. 354–359. Read more.
- Farris, Dominic James, Luke A. Kelly, Andrew G. Cresswell, and Glen A. Litchwark. “The functional importance of human foot muscles for bipedal locomotion.” Proceedings of the National Academy of Sciences of the United States of America. January 29, 2016. Read more.
- Harvard Health Publishing. “Why your feet get bigger as you age.” November 29, 2018. Read more.
- Marks, Julie, and William Morrison, M.D. “All About Wide Feet: Why You Have Them, Concerns, Footwear, and More.” Healthline. August 9, 2019. Read more.
- Cleveland Clinic. “Shoes Getting Tight? Why Your Feet Change Size Over Time.” Health Essentials. January 27, 2020. Read more.
- Holmes, Elizabeth. “Feet Are Getting Bigger, and Many People Wear Shoes That Don’t Fit Right.” The Wall Street Journal. July 14, 2014. Read more.
- Alpert, Natacha. Email interview with Frank Mojica. June 28, July 14, 2021.
- Bayes, Tom. “New SATRA fitting aids.” SATRA Bulletin. June 2020, p. 36. Read more.
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