Lower extremity stiffness when running in minimalist, traditional, and ultra-cushioning shoes

Differences in running mechanics between minimalist (MIN) and traditional (TRAD) running shoes have been the subject of much research in the last decade. More recently, ultra-cushioning (ULTRA) shoes featuring oversized midsoles have emerged and are growing in popularity. However, relatively little is known regarding how ULTRA shoes effect running mechanics. Therefore, the purpose of this study was to compare foot strike, leg stiffness, joint stiffness, and negative joint work when running in MIN, TRAD, and ULTRA shoes. Fifteen recreational runners ran on an instrumented treadmill in each shoe while their whole body kinematics were recorded using a 12-camera motion capture system. Foot strike pattern was quantified using the strike index (SI) and foot strike angle (FSA). Leg stiffness was calculated using a spring-mass model. Joint stiffness was calculated as change in joint moment relative to change in joint angle during the absorption period. Negative joint work was calculated by integrating the negativ...