Current issues in the design of running and court shoes.

This review paper focuses on the three most important functional design factors for sport shoes: injury prevention, performance and comfort. Concepts for these design factors are discussed for running and court shoes. For running shoes, pronation control and cushioning are still considered to be the key concepts for injury prevention despite the fact that conclusive clinical and epidemiological evidence is missing to show the efficacy of these design strategies. Several design features have been proposed to be effective in controlling the amount of pronation. However, the kinematic effects of such features seem to be subject-specific and rather small especially when looking at the actual skeletal motion. Recent running shoe research suggests that cushioning may not or only marginally be related to injuries and that cushioning during the impact phase of running may be more related to aspects such as comfort, muscle tuning or fatigue. For court shoes, lateral stability, torsional flexibility, cushioning and traction control appear to be important design strategies to decrease the risk of injury. With respect to running performance, the shoe concepts of weight reduction, efficiency and energy return are discussed. The concept of energy return does not seem to be a feasible concept whereas concepts which aim to minimize energy loss appear to be more promising and successful, e.g. weight reduction, reduction of muscle energy required for stabilization. For court shoes, optimal traction seems to be the key factor for performance. Research in the area of shoe comfort is still sparse. Cushioning, fitting and climate concepts appear to improve the comfort of both running and court shoes. Many investigations in the area of sport shoe research have shown that subject-specific responses can be expected. Different groups of athletes may require different types of shoes. The definition of these grouping characteristics and their design needs seem to be the most important challenge for the sport shoe researchers and manufacturers for the near future.