Increasing running step rate reduces patellofemoral joint forces.

Area of Science:

• Biomechanics
• Sports Medicine
• Orthopedics

Background:

• Altering running step rate influences joint mechanics.
• Increased step rate is a proposed rehabilitation strategy for patellofemoral pain.
• Understanding effects on muscle forces and joint loads is crucial.

Purpose of the Study:

• Investigate how modifying step rate impacts internal muscle forces and patellofemoral joint loads.
• Identify kinematic and kinetic factors that best predict changes in patellofemoral joint loading.

Main Methods:

• Collected whole-body kinematics from 30 healthy adults running at varied step rates (90%, 100%, 110% of preferred).
• Utilized a 3D musculoskeletal model to estimate muscle, patellar tendon, and patellofemoral joint forces.
• Employed linear regression to determine the influence of limb posture and external loads on patellofemoral joint force.

Main Results:

• Increasing step rate to 110% reduced peak patellofemoral joint force by 14%.
• Peak hip, knee, and ankle extensor forces, along with hip abductor forces, decreased in midstance.
• Peak stance knee flexion reduction was the strongest predictor of decreased patellofemoral joint loading.

Conclusions:

• Increasing step rate effectively reduces patellofemoral joint forces.
• This strategy may modulate biomechanical factors contributing to patellofemoral pain.
• Step rate modification is a viable approach for managing knee pain in runners.