The role of head-in-space stability on stepping reactions in young and elderly adults

Abstract

This study compared head kinematic responses and step latency following an anteriorly directed postural perturbation between two groups (Young, mean age 27.39; Elderly, mean age 71.9). We further attempted to demonstrate, for the first time, a positive linear relationship between sagittal plane head angular velocities and stepping responses in both groups. It was hypothesized that the Elderly would demonstrate higher head angular velocities and greater step latencies than the Young. We also hypothesized that a positive linear relationship would show that, following a perturbation, trials where head angular velocity was low yielded quicker step responses. Each participant experienced three perturbations under five different visual conditions designed to alter visual input and head/trunk coordination. Repeated-measures ANOVA was used, with α set at 0.05. For each test condition, the Elderly consistently demonstrated longer step latencies while exhibiting higher head angular velocities. For each group, a positive linear relationship was shown between the two dependent variables (Young: r=0.86; Elderly, r=0.84). During a postural perturbation, as head angular velocity increased, stepping responses were delayed.

Dynamic control of posture across locomotor tasks

“…Ability to reweight visual information declines with aging, resulting in larger gait deviations in response to visual perturbations in older individuals compared with younger individuals . Older adults also have reduced ability to maintain gaze fixation, and this ability is correlated with gait initiation performance, with those less able to maintain fixation requiring more time to initiate a step . Gaze behaviors during ongoing locomotion also are related to falls .…”

Acquiring visual information for locomotion by older adults: A systematic review

“…Older adults took longer to initiate a step after perturbation but rapid step movements occurred when a fixed visual reference was presented (Diehl and Pidcoe, 2010). Neither older or young adults appeared to use 'online' visual feedback when recovering from a loss of balance even when there was an obstacle to avoid or a target to step on (Zettel et al, 2007).…”

Head movement and its relation to hearing

“…During a loss of balance, an individual must correct their head orientation by making a corrective movement in the form of a step to regain balance, thus allowing the individual to reorient their posture and regain their balance. The ability of a person to regain balance depends, in part, on the time it takes to step and the velocity of the head ( Diehl and Pidcoe, 2011 ; Kowalewski et al, 2018 ). Head velocity in translation (rather than rotation), during the transition from a step to a standing balance is also an important consideration in head stabilization.…”

“…Peak velocity, the highest measured velocity within a specified span of time is useful in these studies for quantifying compensatory movements. In a study where balance was disrupted and individuals were forced to readjust, peak velocity ranged from 150°/s and 100°/s under normal conditions with latency to step initiation measured at approximately 0.30 s. Peak velocity and step latency were strongly correlated, with r values > 0.80: as peak velocity increased, step latency increased for both younger and older cohorts ( Diehl and Pidcoe, 2011 ). In general, older adults also exhibited greater angular velocity than younger adults indicating greater stability compensation ( Diehl and Pidcoe, 2011 ).…”