Fish eye STUDY DESIGN: Controlled laboratory biomechanics study using a repeated-measures, counterbalanced design. Fish eye OBJECTIVES: To compare patellofemoral joint force and stress between a short- and long-step forward lunge both with and without a stride. Fish eye BACKGROUND: Although weight-bearing forward-lunge exercises are frequently employed during rehabilitation for individuals with patellofemoral joint syndrome, patellofemoral joint force and stress and how they change with variations of the lunge exercise are currently unknown. Fish eye METHODS AND MEASURES: Eighteen subjects used their 12-repetition maximum weight while performing a short- and long-step forward lunge both with and without a stride. Electromyography, ground reaction force, and kinematic variables were put into a biomechanical optimization model, and patellofemoral joint force and stress were calculated as a function of knee angle. Fish eye RESULTS: Visual observation of the data show that during the forward lunge, patellofemoral joint force and stress increased progressively as knee flexion increased, and decreased progressively as knee flexion decreased. Between 70° and 90° of knee flexion, patellofemoral joint force and stress were significantly greater when performing a forward lunge with a short step compared to a long step (P<.025). Between 10° and 40° of knee flexion, patellofemoral joint force and stress were significantly greater when performing a forward lunge with a stride compared to without a stride (P<.025). Fish eye CONCLUSIONS: When the goal is to minimize patellofemoral joint force and stress during the forward lunge performed between 0° to 90° knee angles, it may be prudent to perform the lunge with a long step compared to a short step, and without a stride compared to with a stride, because patellofemoral joint force and stress magnitudes were greater with a short step compared to a long step at higher knee flexion angles and were greater with a stride compared to without a stride at lower knee flexion angles.
