Introduction 

Stroke is a leading cause of disability in the United States, with more than 800,000 cases annually. Approximately 55% of chronic stroke survivors exhibit persistent gait asymmetries. Altered ground reaction forces during weight acceptance and push-off contribute to impaired gait performance and can inform rehabilitation strategies. Previous experiments report that asymmetric surface stiffness walking can induce changes in weight bearing in healthy individuals, but the extent to which these results transfer to overground walking is unknown. This study examines whether asymmetric surface stiffness walking induces weight bearing asymmetries that transfer to overground walking.

Methods 

5 healthy individuals participated in this study. Participants first completed a speed test on a 12.5 m overground walkway to determine preferred walking speed, followed by 3 baseline walking trials. Participants then completed a 12-minute walking trial on the AdjuSST [4], including a 2-minute acclimation period and 10 minutes of asymmetric stiffness walking, with one belt set to rigid (300 kN/m) and the other to 15 kN/m. Treadmill speed was set to 15% below preferred overground speed. A final 5-minute overground walking trial was completed to assess aftereffects.

Results 

Immediately following asymmetric surface stiffness walking, vertical ground reaction force (vGRF) increased in the limb exposed to low stiffness relative to baseline, presenting as a vGRF asymmetry. 

Conclusion 

These findings indicate that asymmetric stiffness walking has the capacity to induce short-term changes in midstance and push-off vGRF symmetry, and that these changes partially transfer to overground walking, which is important for any potential gait rehabilitation intervention.