Take your shoes off to reduce patellofemoral joint stress during running.
Patellofemoral joint (PFJ) stress is the most common source of knee pain in runners. There is significant interest in determining the influence of running shoes on factors that contribute to PFJ stress. This study was designed to compare PFJ stresses during barefoot running, and shod running in trained athletes.
22 competitive runners ran overground for 20 trials of 20m, either barefoot or in neutral running shoe (8mm heel-toe differential). Peak PFJ stress, PFJ reaction force, knee extension moment, knee flexion angle, ankle dorsiflexion at footstrike and stride length and stride frequency were analyzed using a Vicon 3D motion analysis system and Kistler force plates. Biomechanical modeling was used to determine Quadriceps force and PFJ contact forces.
Stride length was 2.4% shorter and stride frequency (cadence) was 2% higher barefoot. At footstrike, the ankle was 82% less dorsiflexed barefoot. Peak knee flexion was 4.2% greater with running shoes than barefoot. There was a small increase (0.13%) in PFJ contact with the greater knee flexion angle wearing shoes. Peak knee extension moment was reduced 9% in the barefoot condition, with a 12% reduction in PFJ stress/ joint reaction force.
Running shoes influence kinetics and kinematics of running. There is a reduction of PFJ stress when running barefoot. Shoes with elevated heels cause increased PFJ stress, and can contribute to knee pain in runners. > From: Bonnaci et al., Br J Sports Med (2013) (Epub ahead of print). All rights reserved to Bonnaci et al., published under license by BMJ Publishing Group Ltd.
The Pubmed summary of the article can be found here.