Robotically Controlled Head Oscillations During Overground Walking: A Comparison of Elderly and Young Adults

Abstract

Head turns during walking have been used to assess balance, mobility, and vestibular function in both experimental and clinical applications. However, head turns in walking experiments have been limited to self-initiated head motions as opposed to controlled motions. The aim of this study is to evaluate the effects of controlled head turns enabled by a robotic neck brace in elderly and young adults during overground walking under normal (HO) and altered vision (HVO). The robotic neck brace applied controlled sinusoidal head turns around the vertical axis at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm 30^{\circ }$</tex-math></inline-formula> , 0.4 Hz. The vision was altered using a virtual reality headset, where the visual field was aligned along the direction of the head oscillation. Ten elderly (EA, 65–85 yrs) and ten younger (YA, 22–32 yrs) adults were recruited. Spatiotemporal gait parameters, such as stride length (SL), stride width (SW), stride velocity (SV), stride time (ST), stance time percentage (STP), and direction of progression (DoP), as well as mediolateral and anterior-posterior margins of stability ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ML_{MoS}$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$AP_{MoS}$</tex-math></inline-formula> ) were analyzed. Elderly participants showed greater gait changes than younger individuals, particularly during HVO, leading to the highest DoP deviations. Our results indicate that the elderly had difficulty relying on non-visual cues to compensate for the altered vision. However, they had comparable <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ML_{MoS}$</tex-math></inline-formula> and more stable <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$AP_{MoS}$</tex-math></inline-formula> . Overall, older adults prioritized balance and stability, while young adults focused on preserving walking direction. Our results indicated that age significantly impacts gait during head oscillations, especially when visual information is altered.