Split-Belt Treadmill Training Improves Mechanical Energetics and Metabolic Cost in Women with Unilateral Hip Osteoarthritis: A Proof-of-Concept Study

We have shown that step length asymmetry seen in hip osteoarthritis (OA) is associated with poorer mechanical energy exchange and higher metabolic cost. Thus, we conducted this proof-of-concept study to investigate whether modifying step length through split-belt treadmill training can improve walking energetics. We conducted split-belt treadmill training in four periods with simultaneous motion and metabolic analyses in 10 women with unilateral hip OA. Using repeated measures ANOVA, we evaluated changes across each period, in step length asymmetry, mechanical energy exchange, and O₂ rate. We also examined changes in hip range of motion and peak plantarflexor moment. We used Spearman correlations (rho) to assess the strength of associations between variables at baseline and after adaptation. We found that step length asymmetry and O₂ rate decreased (p = 0.007, p < 0.001) and mechanical energy exchange increased (p < 0.001). Reduced step length asymmetry was associated with reduced O₂ rate (rho = 0.732, p = 0.016). Hip range of motion increased (p < 0.001) and was associated with decreased step length asymmetry (rho = 0.818, p = 0.004), indicating a potential mechanism. These findings suggest that reducing step length asymmetry by split-belt treadmill training could improve walking energetics in hip OA people.