The Sensorimotor Locus of Balance Control in Elderly Gait
| Status: | Completed |
|---|---|
| Conditions: | Other Indications, Orthopedic |
| Therapuetic Areas: | Orthopedics / Podiatry, Other |
| Healthy: | No |
| Age Range: | 65 - Any |
| Updated: | 2/6/2019 |
| Start Date: | October 30, 2017 |
| End Date: | July 25, 2018 |
The aging population is at an exceptionally high risk of debilitating falls, contributing
significantly to reduced independence and quality of life. It remains extremely challenging
to screen for falls risk, and programs designed to mitigate falls risk have only modestly
influenced the sizeable portion of the aging population experiencing one or more falls
annually. Balance control in standing and walking depends on integrating reliable sensory
feedback and on planning and executing appropriate motor responses. Walking balance control
is especially dynamic, requiring active and coordinated adjustments in posture (i.e., trunk
stabilization) and foot placement from step to step. Accordingly, using a custom, immersive
virtual environment, the investigators have shown that sensory (i.e., optical flow)
perturbations, especially when applied during walking, elicit strong and persistent motor
responses to preserve balance. Exciting pilot data suggest that these motor responses are
remarkably more prevalent in old age, presumably governed by an increased reliance on vision
for balance control. Additional pilot data suggest that prolonged exposure to these
perturbations may effectively condition successful balance control strategies. Founded on
these recent discoveries, and leveraging the increase reliance on vision for balance control
in old age, the investigators stand at the forefront of a potentially transformative new
approach for more effectively identifying and mitigating age-related falls risk. The
investigator's overarching hypothesis is that optical flow perturbations, particularly when
applied during walking, can effectively identify balance deficits due to aging and falls
history and can subsequently condition the neuromechanics of successful balance control via
training.
significantly to reduced independence and quality of life. It remains extremely challenging
to screen for falls risk, and programs designed to mitigate falls risk have only modestly
influenced the sizeable portion of the aging population experiencing one or more falls
annually. Balance control in standing and walking depends on integrating reliable sensory
feedback and on planning and executing appropriate motor responses. Walking balance control
is especially dynamic, requiring active and coordinated adjustments in posture (i.e., trunk
stabilization) and foot placement from step to step. Accordingly, using a custom, immersive
virtual environment, the investigators have shown that sensory (i.e., optical flow)
perturbations, especially when applied during walking, elicit strong and persistent motor
responses to preserve balance. Exciting pilot data suggest that these motor responses are
remarkably more prevalent in old age, presumably governed by an increased reliance on vision
for balance control. Additional pilot data suggest that prolonged exposure to these
perturbations may effectively condition successful balance control strategies. Founded on
these recent discoveries, and leveraging the increase reliance on vision for balance control
in old age, the investigators stand at the forefront of a potentially transformative new
approach for more effectively identifying and mitigating age-related falls risk. The
investigator's overarching hypothesis is that optical flow perturbations, particularly when
applied during walking, can effectively identify balance deficits due to aging and falls
history and can subsequently condition the neuromechanics of successful balance control via
training.
Specific Aim 1. Investigate sensory, motor, and cognitive-motor mechanisms governing
susceptibility to optical flow perturbations. Aging increases the reliance on vision for
balance control. However, central and peripheral mechanisms underlying aging and falls
history effects on the susceptibility to optical flow perturbations are unclear. Hypothesis
1: Entrainment to optical flow perturbations will correlate most strongly with visual
dependence and decreased somatosensory function, alluding to an age-associated process of
multi-sensory reweighting. Methods: Multivariate models will quantify the extent to which
strategically-selected sensory (i.e., visual dependence via rod/frame test, somatosensory
function), motor (i.e., rate of torque development, timed sit-to-stand) and cognitive-motor
(i.e., interference) mechanisms underlie inter-individual differences in susceptibility to
perturbations.
Specific Aim 2. Estimate the efficacy of prolonged optical flow perturbations to condition
the neuromechanics of walking balance control in older adult fallers. Pilot data from young
adults suggests that prolonged exposure to optical flow perturbations may condition reactive
strategies used to successfully control walking balance. The investigator's premise is that
dynamic perturbation training can improve resilience to unexpected balance disturbances.
Here, the investigators conduct a preliminary test of the effects of training with optical
flow perturbations on walking balance in older adult fallers. Hypothesis 2: (a) Older adults
with a history of falls will adapt to prolonged exposure to perturbations, conditioning their
step to step adjustments in walking balance control, and (b) improving their response to
unexpected balance challenges following training. Methods: In two 20 min sessions, on
different days in a randomized cross-over design, older adults with a history of falls will
walk with ("treatment" session) and without ("control" session) prolonged exposure to optical
flow perturbations. The investigators will assess time-dependent changes in the
neuromechanics of walking balance during training and after-effects via gait variability,
dynamic stability, and performance on a series of real-world like targeting and obstacle
avoidance tasks.
susceptibility to optical flow perturbations. Aging increases the reliance on vision for
balance control. However, central and peripheral mechanisms underlying aging and falls
history effects on the susceptibility to optical flow perturbations are unclear. Hypothesis
1: Entrainment to optical flow perturbations will correlate most strongly with visual
dependence and decreased somatosensory function, alluding to an age-associated process of
multi-sensory reweighting. Methods: Multivariate models will quantify the extent to which
strategically-selected sensory (i.e., visual dependence via rod/frame test, somatosensory
function), motor (i.e., rate of torque development, timed sit-to-stand) and cognitive-motor
(i.e., interference) mechanisms underlie inter-individual differences in susceptibility to
perturbations.
Specific Aim 2. Estimate the efficacy of prolonged optical flow perturbations to condition
the neuromechanics of walking balance control in older adult fallers. Pilot data from young
adults suggests that prolonged exposure to optical flow perturbations may condition reactive
strategies used to successfully control walking balance. The investigator's premise is that
dynamic perturbation training can improve resilience to unexpected balance disturbances.
Here, the investigators conduct a preliminary test of the effects of training with optical
flow perturbations on walking balance in older adult fallers. Hypothesis 2: (a) Older adults
with a history of falls will adapt to prolonged exposure to perturbations, conditioning their
step to step adjustments in walking balance control, and (b) improving their response to
unexpected balance challenges following training. Methods: In two 20 min sessions, on
different days in a randomized cross-over design, older adults with a history of falls will
walk with ("treatment" session) and without ("control" session) prolonged exposure to optical
flow perturbations. The investigators will assess time-dependent changes in the
neuromechanics of walking balance during training and after-effects via gait variability,
dynamic stability, and performance on a series of real-world like targeting and obstacle
avoidance tasks.
Inclusion Criteria:
- Be able to walk without an assistive aid (i.e., walker, cane)
- Have the full capacity to provide informed consent
OLDER NON-FALLERS
- Age 65+ years
- No history of falls* in the prior 12 months
OLDER ADULTS WITH A HISTORY OF FALLS
- Age 65+ years
- History of one or more falls* in the prior 12 months
- For the purposes of this study, falls counted towards the self-reported total
will be defined as per the Kellogg International Work Group - a fall is
"unintentionally coming to the ground or some lower level and other than as a
consequence of sustaining a violent blow, loss of consciousness, sudden onset of
paralysis as in stroke or an epileptic seizure"
Exclusion Criteria:
- Current lower extremity injury or fracture
- Taking medication that causes dizziness
- Have a leg prosthesis
- Prisoners
- Individuals clearly lacking the capacity to provide informed consent
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