Effect of forward-directed aiding force on gait mechanics in healthy young adults while walking faster

Abstract

Background: Forces can be applied to people while they are walking on a treadmill in different ways that aid individuals to walk at faster walking speeds with potentially less effort. Forward-directed aiding forces (FAF) are a special class of aiding forces where "push" or "pull" forces are mechanically applied to the person's pelvis in the forward direction.

Objective: To determine if FAF, applied by a robotic interface, can be effective in providing assistance to walk at a faster walking speed with reduced kinetic requirements.

Methods: Twenty non-neurologically impaired physical active young adults were recruited and biomechanical gait mechanics were measured during walking at two constant treadmill belt speeds (1.0 m/s and 1.6 m/s), with the robotic device in aiding mode to provide FAF (FAF), and also outside of the robotic device (no-FAF). The spatiotemporal gait parameters, anterior-posterior force, sagittal impulse, and hip, knee and ankle power and net work were calculated from kinematic and kinetic data, comparing changes in parameters from slower to faster speeds within each mode, and then, comparing values between each mode.

Results: The spatiotemporal gait parameters were not different between conditions, but in FAF condition, the propulsive force impulse change was not increased, there was smaller propulsion increase, and smaller maximal power generation and ankle work done at the faster speed, whereas all of these parameters were appropriately increased in the no-FAF condition.

Conclusions: These results indicate that providing FAF at the pelvis is an effective means for reducing the amount of mechanical effort required to walk faster and thus could be used as a training tool to improve walking ability.

Keywords: Gait speed; Ground reaction forces; Human-robot interaction; Mechanical work; Treadmill.