Biomechanical of bilateral heel rise, and its association with balance, functional mobility, and walking speed in older adults

Introduction: Aging advancing decreases ankle-foot strength and mobility, affecting gait and balance control. The heel-rise (HR) task requires the ankle-foot to control different biomechanical demands. It is still unclear whether these demands during HR are associated with functional performance in older adults. The aim was to describe the association between HR biomechanical parameters and single-leg stability, functional mobility, and walking speed in community-dwelling older adults. Methods: Sixty-nine older adults (73.0, SD 6.8 years) were tested on a force platform performing bilateral rapid HR in the rise and drop phases. The biomechanical parameters measured were peak force and time, impulse, root mean square and displacement of the center of pressure (CoP), as well as displacement and velocity of the center of mass (CoM), and vertical stiffness. Functional performance was assessed through balance using the single-leg stance test (SLS), functional mobility with the Timed Up & Go test (TUG), and walking speed (WS). Associations between functional tests and biomechanical parameters were determined using correlation tests. Results: HR peak strength and time showed a medium to large association with TUG and WS but not SLS. CoP anteroposterior displacement showed a large association in the drop phase with all functional tests but not in the rise phase. CoM velocity and vertical stiffness were associated with all tests in both phases. Conclusion: Older adults HR biomechanical parameters are more closely associated with functional mobility and walking speed tests (TUG and WS) than with static balance tests such as SLS.