Age-related modifications in steering behaviour: effects of base-of-support constraints at the turn point

Abstract

This study investigated the effects of altering the base of support (BOS) at the turn point on anticipatory locomotor adjustments during voluntary changes in travel direction in healthy young and older adults. Participants were required to walk at their preferred pace along a 3-m straight travel path and continue to walk straight ahead or turn 40 degrees to the left or right for an additional 2-m. The starting foot and occasionally the gait starting point were adjusted so that participants had to execute the turn using a cross-over step with a narrow BOS or a lead-out step with a wide BOS. Spatial and temporal gait variables, magnitudes of angular segmental movement, and timing and sequencing of body segment reorientation were similar despite executing the turn with a narrow or wide BOS. A narrow BOS during turning generated an increased step width in the step prior to the turn for both young and older adults. Age-related changes when turning included reduced step velocity and step length for older compared to young adults. Age-related changes in the timing and sequencing of body segment reorientation prior to the turn point were also observed. A reduction in walking speed and an increase in step width just prior to the turn, combined with a delay in motion of the center of mass suggests that older adults used a more cautious combined foot placement and hip strategy to execute changes in travel direction compared to young adults. The results of this study provide insight into mobility constraints during a common locomotor task in older adults.

Effect of walking velocity on segment coordination during pre-planned turns in healthy older adults

“…These delay times are shorter than what has been reported as the relative delay in trunk reorientation in healthy young adults by Patla et al [3] (300 ms), and Grasso et al [14] (440 ms). Our results are closer to the results of Carpinella et al [6] who showed delays of 140 and 230 ms for upper trunk and pelvis relative to the head as healthy elderly made a 908 left turn in the middle of their walk, and the results of Paquette et al [4] who reported 228 ms delay in rotation of trunk as healthy elderly made a 408 turn in the middle of their walk.…”

“…Healthy young adults modify their foot placement and trunk roll motion at the initiation of a turn to control and move their body center of mass towards the new direction of travel. This is followed by movements in the yaw plane, which start from the head, proceed to the trunk, and end at the foot in a top-down manner [3,4]. A similar top-down sequence in segment reorientation also has been reported in healthy elderly as they turn in the middle of their walk [5][6][7][8].…”

Action strategies of older adults walking through apertures

“…When passing through confined spaces, older adults require a larger safety margin in order to be successful. This agerelated cautious behaviour has been reported previously during steering tasks [10] and when cognitive demands are increased [11].…”

Visuomotor adaptation of voluntary step initiation in older adults

“…They also show delays in reorienting the center of mass when turning [8] and poor anticipatory postural adjustments when attempting to counter inertial perturbations induced by their own moving limbs [9,10]. Impaired interlimb coordination and reduced anticipatory muscle activation patterns in the legs during gait initiation are also characteristic of this population [11,12].…”