Effects of step length on patellofemoral joint stress in female runners with and without patellofemoral pain.

Background: Patellofemoral pain is common among runners and is frequently attributed to increased patellofemoral joint stress. The purpose of our study was to examine the effects of changing step length during running on patellofemoral joint stress per step and stress per mile in females with and without patellofemoral pain.

Methods: Ten female runners with patellofemoral pain and 13 healthy female runners performed running trials at 3.