Mechanistic Causes of Increased Walking Speed After a Strength Training Program in Stroke Patients: A Musculoskeletal Modeling Approach

While strength training interventions improve walking performance in stroke survivors, the underlying neuromuscular mechanisms remain poorly understood. This study investigated muscle-level adaptations following a 12-week moderate-to-high intensity strength training program in ten chronic stroke survivors using comprehensive musculoskeletal modeling analysis. Three-dimensional gait analysis was performed pre- and post-intervention, with subject-specific OpenSim models estimating individual muscle forces, powers, and work capacities throughout stance phase. Knee extensor force generation increased during loading response in both limbs. During push-off, ankle plantarflexor force generation improved bilaterally, primarily through paretic soleus and gastrocnemius contributions, though power output remained unchanged, indicating persistent velocity-dependent muscular deficits. Non-paretic hip flexor negative work capacity increased significantly (0.280 to 0.335 J/kg, p=0.033), driven by enhanced rectus femoris power absorption during late stance that mechanistically facilitated trunk acceleration through leg deceleration. Improved gait performance in both sides demonstrates that strength training produces functionally beneficial bilateral muscle-level reorganization, supporting its integration into comprehensive stroke rehabilitation protocols targeting locomotor recovery.