Biomechanics and Motion Analysis

Wear Characteristics of Common Running Shoe Materials

Principal Investigator: Jay Smith, M.D. and Kenton R. Kaufman, Ph.D.
Project Coordinator: Kathie Bernhardt — bernhardt.kathie@mayo.edu

Figure 20: Shoe mounted in instrumented impact tester

Shock absorption capabilities of running shoes are known to deteriorate over time. The purpose of this study was to determine the pattern of shock absorption degradation in currently available footwear materials.

Six of the most popular "cushioning" class shoes were selected for the study. Five styles had EVA based mid-soles (Adidas Supernova Cushioned, Asics Gel Nimbus III, New Balance 1021, Reebok Medallion, and Saucony Grid Trigon Responsive) and one had an air shock absorption system (Nike Air Max Elite R4).

Initial shock absorption properties were measured with a free-fall type impact tester instrumented with force and position transducers (Figure 20). Shock absorption capacity was measured with the instrumented impact tester every 25 miles for the first 100 miles run. After the first 100 miles, shock absorption capacity was measured at 160, 200, 260, 300, and so on until 600 miles were completed.

Data is currently being compiled and analyzed. Comparisons are being made between shock absorption capacity of the different shoes at various mileage landmarks and between the shock absorption capacity of each shoe. The outcome of this study may provide runners with insight on which footwear materials will retain their shock absorption properties over time and potentially provide mileage milestones for changing shoes when training.