Hip external rotation stiffness and midfoot passive mechanical resistance are associated with lower limb movement in the frontal and transverse planes during gait

Background: Hip external rotation stiffness, midfoot passive mechanical resistance and foot alignment may influence on ankle, knee and hip movement in the frontal and transverse planes during gait. Research question: Are hip stiffness, midfoot mechanical resistance and foot alignment associated with ankle, knee and hip kinematics during gait? Methods: Hip stiffness, midfoot mechanical resistance, and foot alignment of thirty healthy participants (18 females and 12 males) with average age of 25.4 years were measured. In addition, lower limb kinematic data during the stance phase of gait were collected with the Qualisys System (Oqus 7 +). Stepwise multiple linear regressions were performed to identify if hip stiffness, midfoot torque, midfoot stiffness and foot alignment were associated with hip and knee movement in the transverse plane and ankle movement in the frontal plane with ( )alpha = 0.05. Results: Reduced midfoot torque was associated with higher hip range of motion (ROM) in the transverse plane (r(2) = 0.18), reduced hip stiffness was associated with higher peak hip internal rotation (r(2) = 0.16) and higher ROM in the frontal plane (r(2) = 0.14), reduced midfoot stiffness was associated with higher peak knee internal rotation (r(2) = 0.14) and increased midfoot torque and midfoot stiffness were associated with higher peak knee external rotation (r(2) = 0.36). Significance: These findings demonstrated that individuals with reduced hip and midfoot stiffness have higher hip and knee internal rotation and higher ankle eversion during the stance phase of gait. On the other hand, individuals with increased midfoot torque and stiffness have higher knee external rotation. These relationships can be explained by the coupling between ankle movements in the frontal plane and knee and hip movements in the transverse plane. Finally, this study suggests that midfoot passive mechanical resistance and hip stiffness should be assessed in individuals presenting altered ankle, knee and hip movement during gait.