Upper

Probably the main reason to have an upper at all is to hold the midsole and outsole to the bottom of the foot. This aspect of the upper is most obvious when one studies old shoes from sports like running and basketball. The upper was a leather, canvas or nylon enclosure that could be tied so as to hold the protective outsole on the foot. Not much attention was paid to how well the shoe fit, basically because no one really needed to. Until athletes started to push the limits of their footwear, did designers and scientists start to wonder how they could be improved. This focus brought about changes that focused on improving fit in the upper as well as enhancing the flexibility, stability and support functions. Interestingly enough, some shoes are returning to their roots in the sense that they are being minimized to function as just a way to hold an outsole to the foot. In some ultra-light racing shoes the uppers are primarily lycra socks attached to foam midsole/outsole combinations. The idea here is to provide a design that minimizes weight but will allow some cushioning during a race.

Fit - Designers must pay attention to how a shoe fits on the foot. The overall quality of the fit is based on the last that the shoe is built around. Lasts are basically models of the foot. The better the model of the foot, the better the last. Sport researchers help to build better lasts by taking pictures of thousands of feet and analyzing them (see the section on video analysis). Another of the sub-systems that affects the fit of a shoe is the lacing system. Lacing systems can vary from the "traditional" shoestring to Velcro, even to no lace systems that allow one to slip the shoe on like a slipper. Another part of the upper that is involved in fit is the heel counter. This piece helps to hold the shoe firmly in place around the heel region. The heel and ankle region are important to think about when designing an upper. A heel counter that does not conform to the heel will allow the heel to move around too much and can effect stability leading to injury.

Stability - The upper, along with the midsole, are the most important contributors to the ability of a shoe to protect against potentially injurious motions of the foot and ankle. In basketball, for example, a "high top" or "three quarter" height upper may provide more support to the ankle and help prevent players from spraining an ankle. Stability and motion control are key areas for study using video analysis techniques that look at pronation and supination.

Durability - The ability of the upper to contribute to stability, maintain its shape, provide optimal flexibility, and protect the foot from abrasions and injuries is directly related to the materials used to construct it. In selecting materials the designer must take into account the specific sport the shoe is being designed for. For example, a shoe designed for rock climbing will have distinctly different durability needs than a shoe designed for basketball. In fact, the overall design of the upper may vary by position in a specific sport--a pitcher in baseball needs a design that provides durability in the toe area while a shoe used in other positions may not. Other factors that the designer must also take into consideration include such things as diverse as the overall weight of the shoe, the aesthetics (how it looks) and the "price point" (how much the shoe will cost) as this will influence the types of materials that can be used. These last two points, aesthetics and price point, bring up an interesting aspect of sport research and its application to shoe design and even, in a broader sense, sports in general. This is, of course, the pull between research and marketing. It is an interesting exercise, and worthwhile from an informed consumer viewpoint, to have students consider how much of a shoe's appeal (usually directly related to cost) is due to the "look" of the shoe vs. the functionality. There is no doubt that the application of sport research has improved the quality and functionality of sports equipment and the performance of athletes. However, where this improvement ends and the marketing begins is a question worth considering.

Flexibility - In some sports a very stiff shoe is more advantageous while in others more flexible shoes are needed. For example, a place-kicker in American football might need a shoe that is very stiff in the forefoot region, while a runner would need a shoe that flexes along the natural flex lines in the foot. In general, when considering flexibility the designer and scientist focus on these natural flex lines in the foot, the area in the forefoot between the ball of the foot and the toes where the foot flexes while running. When considering flexibility there is usually a trade-off between overall durability and stability.