Fall history in older adults impacts acceleration profiles after a near collision with a moving pedestrian hazard.

BACKGROUND: Environmental hazards (e.g., pedestrian traffic) cause falls and testing environment impacts gait in older adults. However, most fall risk evaluations do not assess real-world moving hazard avoidance. AIMS: This study examined the effect of fall history in older adults on acceleration profiles before, during, and after a near collision with a moving hazard, in laboratory and real-world settings. METHODS: Older adults with (n = 14) and without a fall history (n = 15) performed a collision avoidance walking task with a sudden moving hazard in real-world and laboratory settings. Gait acceleration and video data of participants' first-person views were recorded. Four mixed effects multilevel models analyzed the magnitude and variability of mean and peak anteroposterior and mediolateral acceleration while walking before, during, and after the moving hazard in both environments. RESULTS: In the real-world environment, older adults without a fall history increased their mean anteroposterior acceleration after the moving hazard (p = 0.046), but those with a fall history did not (p > 0.05). Older adults without a fall history exhibited more intersubject variability than those with a fall history in mean (p < 0.001) and peak anteroposterior (p = 0.015) acceleration across environments and epochs. Older adults without a fall history exhibited a slower peak mediolateral reaction during the moving hazard (p = 0.014) than those with a fall history. CONCLUSIONS: These results suggest that compared to older adults with a fall history, older adults without a fall history are more adaptable and able to respond last-minute to unexpected hazards. Older adults with a fall history exhibited more homogenous responses.

Dual-tasking impacts gait, cognitive performance, and gaze behavior during walking in a real-world environment in older adult fallers and non-fallers.

INTRODUCTION: Everyday walking often involves simultaneous performance of a cognitive task in environments with competing auditory and visual stimuli. Previous research has not evaluated task performance in these situations, where older adults are known to fall, limiting our understanding of how older adults adjust their gait, visual scanning (gaze), and cognitive processing to avoid falls (or not). The purpose of this study was to examine the effect of dual-task walking in a high-distraction real-world environment on cognitive performance, gait performance, and gaze behavior in older adult fallers relative to non-fallers. METHODS: Fourteen community-dwelling, older adult fallers (76.6 ± 9.1 years, 11 females) and 15 community-dwelling, older adult non-fallers (77.4 ± 7.6 years, 11 females) participated. Participants performed single-task walking, single-task cognitive (seated category naming), and dual-task walking (category naming + walking) trials for 1 min each in a real-world environment (busy hospital lobby). Gait speed, stride length variability, stride duration variability, gaze fixation duration on 6 areas of interest (AOIs), and percentage of time fixating on 6 AOIs were recorded during single- and dual-task walking trials. Number of correct responses, time to first response, and mean subsequent response time (measure of rate of decline of response retrieval throughout trial) were determined for single-task cognitive and dual-task walking trials. Two-way MANCOVAs and MANOVAs were used to compare the effects of fall status and task condition on gait and cognitive variables. Hierarchical linear regression models were used to assess predictors of gaze behavior variables. RESULTS: Compared to single-task, during dual-task trials, participants walked 0.21 m/s slower, had 1.5 fewer verbal responses, and a 2823 ms shorter mean subsequent response time, indicating a faster declining rate of retrieval during the cognitive task. Additionally, during dual-task walking, participants fixated their gaze on Far People (AOI) for a significantly smaller percentage of time and on the Near Walking Path (AOI) for a significantly greater percentage of time than during single-task walking. During all trials, being a non-faller predicted a longer average fixation duration on the Far Environment (AOI) than for fallers. Environmental busyness, baseline gait speed, and baseline executive function impacted gaze behavior. CONCLUSION: All participants exhibited dual-task decrements in gait and cognitive performance and changes in gaze behavior from single- to dual-task walking. Perhaps of more importance, non-fallers appear to have had more freedom to divert their gaze to less relevant environmental stimuli while walking, and two measures of fall risk impacted patterns of gaze behavior differently. Thus, overt visual attention during walking in real-world environments should be further explored in relation to fall risk.

Effect of the environment on gait and gaze behavior in older adult fallers compared to older adult non-fallers.

INTRODUCTION: Compared to controlled laboratory settings, the real world is highly distracting with constant demands on visual attention to avoid hazards and falling. Fall-risk assessments do not adequately take into account the potential role of everyday distractions and environmental hazards. The purpose of this project was to identify the effect of the environment on gait and gaze behavior during walking in older adult fallers relative to non-fallers. METHODS: Thirteen older adult fallers (76.8±9.4 years, 3.2±2.3 falls in last year) and 13 age-matched non-fallers (78.3±7.3 years, 0 falls in last year) participated. Participants walked in a real-world and lab setting while gait and gaze were recorded. Gait variables were stride length variability, stride duration variability, and stride velocity. Gaze was analyzed for percentage of time fixating and average fixation duration coded across 6 areas of interest (AOIs) in the visual surroundings. RESULTS: Non-fallers walked faster than fallers, but there were no other group or environment effects on gait. For gaze behavior, fallers had shorter fixation durations on the near environment than non-fallers, but only in the real world. In the real world relative to the lab, fallers decreased fixation durations on the near environment but increased durations on near people. In the real world, participants spent a greater proportion of time fixating on people than on the walking path or the near environment compared to the lab. After adjusting for baseline gait speed, fallers had shorter fixation durations than non-fallers in both environments. CONCLUSIONS: Our results indicate that in a busy environment, older adults concentrate most of their overt visual attention on people when navigating their walking path. Fallers in particular focus longer on people near to them and have overall shorter fixations than non-fallers. Visual focus while walking in a busy environment should be further explored as a fall-risk factor.

Relationships between gait variability and ambulatory activity post stroke.

BACKGROUND: Fall risk and balance confidence are related to gait variability and ambulatory activity post stroke, yet whether a relationship exists between gait variability and ambulatory activity is unknown. Knowing if gait variability measured under naturalistic conditions is related to ambulatory activity could explain more about the relationship between falls and walking activity post-stroke. OBJECTIVES: To examine relationships between spontaneous, daily ambulatory activity and gait variability during single- and dual-task walking, in low- and high-distraction settings in adults post stroke. METHODS: Sixteen community-dwelling adults post stroke participated in a cross-sectional study. Spatiotemporal gait parameters were recorded during single- and cognitive-motor dual-task walking in low- and high-distraction settings. Coefficient of variation was calculated for stride length and stride duration. Average walking bout duration, maximum walking bout duration, and total number of steps per day were captured using an activity monitor. Correlations between ambulatory activity measures and gait variability were examined. RESULTS: In the high-distraction setting, single-task stride duration variability was negatively related to all three ambulatory activity measures, but the strongest relationship was a negative correlation between dual-task stride duration variability and average walking duration. In the low-distraction setting, single-task stride duration variability was negatively related to maximum walking duration. None of the other variability measures were related to ambulatory activity. CONCLUSIONS: The finding that stride duration variability in a high-distraction environment, with or without an additional cognitive task, is related to ambulatory activity in community-dwelling stroke survivors suggests that assessments incorporating attentional demands of real-world walking may be useful additions to clinical practice.

Relationship Between Dual-Task Gait Speed and Walking Activity Poststroke.

BACKGROUND AND PURPOSE: Gait speed does not adequately predict whether stroke survivors will be active in the community. This may be because traditional single-task gait speed does not sufficiently reproduce the demands of walking in the real world. This study assessed whether dual-task gait speed accounts for variance in daily ambulatory activity above what can be predicted with habitual (single task) gait speed in community-dwelling stroke survivors. METHODS: Twenty-eight community-dwelling individuals, 58.2 years of age (SD=16.6), 8.9 months poststroke (interquartile range, 3.7-19.4), completed a gait and cognitive task in single- and dual-task conditions. Daily ambulatory activity was captured using a physical activity monitor. A regression analysis examined R2 changes with single- and dual-task gait speed. RESULTS: Single-task gait speed explained 15.3% of the variance in daily ambulatory activity (P=0.04). Adding dual-task gait speed to the regression model increased the variance explained by an additional 20.6% (P=0.04). CONCLUSIONS: Gait speed assessed under attention-demanding conditions may improve explanation of variance in daily ambulatory activity after stroke.

A structural equation model relating physical function, pain, impaired mobility (IM), and falls in older adults.

The current study used a structural equation model to investigate the interrelationships among physical function, pain, IM, and falls in 511 American older adults. The model included 11 measurement variables (tandem stance, single leg stance, 360° turn, chair stand, arm curl, sit and reach, back scratch, normative score of 6-min walk or 2-min step, timed up and go, pain, and fall) and four latent variables (balance, strength, flexibility, and IM). The final model with the combined sample demonstrated good fit with the participant data (χ(2)(31)=30.0, N=499, p=0.52; Goodness of Fit Index (GFI)=0.99). Balance had a significant and the largest effect on IM (standardized regression weights=-1.05, p<0.001). Strength, endurance, flexibility, and pain had small effects on IM (standardized regression weights<0.2). The findings suggest that balance and mobility testing should be a priority in fall screening and prevention programs.

The effect of an exercise-based balance intervention on physical and cognitive performance for older adults: a pilot study.

BACKGROUND: Several exercise-based falls prevention interventions produced significant long-term reductions in fall rate, but few demonstrate long-term improvements in falls risk factors. A strong body of evidence supports a protective effect of aerobic or strength-training exercise on cognition. Individuals participating in an exercise-based balance improvement program may also experience this protective effect. This may contribute to the decreased rate of falls reported in the literature. PURPOSE: To determine if individuals participating in an evidence-based exercise program to reduce falls would demonstrate improvements in both physical and cognitive performance. METHODS: In this nonexperimental, pretest, posttest design study, 76 adults (65-93 years) participated in a scripted 12-week, 24 session exercise-based balance improvement program. Each 60 minute class incorporated balance, strength, endurance, and flexibility exercises. Participants completed baseline assessments of physical and cognitive performance measures 1 week prior and 1 week following the intervention. RESULTS: Fifty-two participants completed posttest measures. There were significant improvements in 3 physical performance measures (chair rise time, 360 degree turn, and 4 square step test). There also was similar improvement in the Symbol Digit Modality Test, a measure of processing speed and mental flexibility. When participants were dichotomized into 2 groups based on achieving/not achieving, a baseline walking speed of at least 1.0 meters/second, secondary analysis revealed greater improvements in cognitive performance measures of Trails A and Trails B tests by faster walkers compared to slower walkers. CONCLUSIONS: Participation in balance programs can have a positive impact on cognition and physical outcomes. This may provide insight about how exercise influences fall risk. Therapists can utilize this information clinically by educating patients about the potential positive effect of balance exercises on cognition.

A pilot study: coordination of precision grip in children and adolescents with high functioning autism.

PURPOSE: This pilot study compared temporal coordination during a precision grip task between 13 children and adolescents with autism spectrum disorders (ASD) who were high functioning and 13 peers with typical development. METHODS: Temporal coordination between grip and load forces was measured using latency between onset of grip and load forces, grip force at onset of load force, peak grip force (PGF), and time to PGF. RESULTS: Compared with peers with typical development, participants with ASD demonstrated prolonged latency between grip and load forces, elevated grip force at onset of load force, and increased movement variability. PGF and time to PGF were not significantly different between the 2 groups. CONCLUSIONS: These findings indicate temporal dyscoordination in participants with ASD. The findings also enhance our understanding of motor coordination deficits in persons with ASD and have theoretical as well as clinical implications.

Physical performance characteristics of assisted living residents and risk for adverse health outcomes.

PURPOSE: Researchers know little about the physical performance ability of residential care/assisted living (RC/AL) residents and its relationship to adverse outcomes such as fracture, nursing home placement, functional decline, and death. The purposes of this article are to (a) describe the functional characteristics of RC/AL residents, (b) examine the relationships between resident- and facility-level characteristics and physical performance, and (c) determine the predictive value of physical performance for adverse outcomes. DESIGN AND METHODS: Data came from 1,791 residents in 189 RC/AL facilities participating in the Collaborative Studies of Long-Term Care. At baseline, residents were tested on four performance measures (grip strength, chair rise, balance, and walking speed), and other resident- and facility-level information was collected. Adverse outcomes were measured over 1 year. RESULTS: Average grip strength was 14 +/- 7 kg, 61% of residents walked <0.6 m/s (M = 0.41 m/s), 26% could perform five chair rises, and only 19% could perform a tandem stand for a least 1 s. Multivariable analyses showed that more cognitive and functional impairment, depressive symptoms and comorbid conditions, and for-profit ownership were associated with poorer physical performance. Controlling for individual characteristics, we found that better performance on the four physical performance measures was associated with a reduced risk of nursing home placement, fracture, and decline in function over 1 year. IMPLICATIONS: Simple performance measures identify modifiable functional deficits and suggest targeted interventions to prolong independent mobility and aging in place in RC/AL facilities.

Orthotic aided training of the paretic upper limb in chronic stroke: results of a phase 1 trial.

This was a phase 1 investigation of an upper limb training program using the SaeboFlex dynamic orthosis to improve upper limb motor status. Thirteen individuals with chronic hemiparesis from stroke (age 26-71 years) participated. After being fitted with a SaeboFlex orthosis, each participant was engaged in 5 days of training (6 hours per day) that consisted of repetitive, task oriented activities with the SaeboFlex, exercises, and functional electrical stimulation. Individuals demonstrated improvements in movement at the shoulder and elbow. Wrist extension also improved, but wrist flexion and finger movement did not. Two more global measures of upper limb status improved. Muscle tone decreased. All participants remained pain free. This investigation demonstrates that a program using the orthosis was accompanied by many desirable changes and no untoward consequences.

Are scores on balance screening tests associated with mobility in older adults?

PURPOSE: To examine associations between measures of static and dynamic balance and performance of mobility tasks in older adults. METHODS: A cross-sectional analysis from 95 community dwelling participants (mean age 80.9 years, range 65 -03 years). Participants performed tests of static (tandem stance) and dynamic (360 degrees turn) balance and mobility (walking speed and timed chair rise). Associations among balance and mobility measures were examined using correlation and logistic regression. RESULTS: Static and dynamic balance were moderately associated (r = -.462). Relationships between dynamic balance and mobility were stronger than those between static balance and mobility. The association between dynamic balance and walking speed was particularly strong (r = -.701 ). Using logistic regression, age, and balance performance were significant predictors for outcomes of walking speed (dichotomized to < .0 m/s, >/= .0 m/s), and timed chair rise (dichotomized to 3.6 s). Faster 360 degrees turn times were independently associated with faster walking speed and chair rise time. CONCLUSION: Mobility tasks require both dynamic and static balance. As falls are a major health risk for older adults, including brief assessments of dynamic and static balance in the examination of older adults provides valuable information about physical function and mobility.

Relationship between hip abductor rate of force development and mediolateral stability in older adults.

OBJECTIVE: To examine the relationship between hip abductor rate of force development (RFD) and performance of reactive and voluntary balance tasks in older adults. DESIGN: Descriptive study using correlation and regression analyses. SETTING: University research laboratory. PARTICIPANTS: A volunteer sample of 30 community-dwelling men and women over the age of 65 years. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Measures of hip abductor RFD, center of pressure (COP) displacement during compensatory stepping, and scores on 1-leg standing (OLS), and tandem gait tests. Hip abductor RFD was defined as the time required to go from 10% of maximum force to 60% of maximum force (10%-60% RFD) or to 90% of maximum force (10%-90% RFD). RESULTS: Hip abductor RFD did not correlate with COP displacement during compensatory stepping, but did correlate significantly with OLS and tandem gait variables (P<.05). In predicting OLS scores, age (beta=-.485, P<.05) and 10% to 60% RFD (beta=-.354, P<.05) were significant predictors. In predicting tandem gait scores, 10% to 90% RFD (beta=.384, P<.05) was the only significant predictor in the final regression model. CONCLUSIONS: Hip abductor RFD, tested under voluntary conditions, correlated with performance of clinical tests that challenge lateral stability. Our results support the idea that voluntary and reactive balance tasks involve different types of neuromuscular control.

Characteristics of stepping over an obstacle in community dwelling older adults under dual-task conditions.

Previous research suggests that older adults may have difficulty attending to simultaneous tasks. This study was conducted to determine how concurrent performance of a secondary cognitive task influences walking and stepping over an obstacle in community dwelling older adults. Twenty-one men and women with a mean age of 73.4 years (S.D.=5.3) participated in the study. Subjects performed a gait task both alone (single-task condition) and in combination with a cognitive task that involved reciting numbers (dual-task condition). In the gait task, each subject walked at his/her fastest speed along a 10-m walkway and stepped over an obstacle designed to simulate a door threshold. Paired t-tests were used to compare gait parameters (10 m gait speed, gait speed during obstacle approach and negotiation, medial-lateral center of pressure excursion and velocity during obstacle negotiation, foot clearance over the obstacle, step length and foot position relative to the obstacle) and cognitive task performance under single and dual-task conditions. Toe-obstacle distance was greater and obstacle-heel distance was reduced under dual-task conditions. Performance of the remaining gait parameters did not change with the addition of a secondary cognitive task. Cognitive task performance decreased under dual-task conditions. These community dwelling older adults demonstrated minimal or no change in measured gait parameters during simultaneous performance of a cognitive task. The observed decrement in cognitive task performance suggests that subjects may have placed a higher priority on gait performance.

Intrasession and intersession reliability of handheld dynamometry in children with cerebral palsy.

PURPOSE: The primary purpose of this study was to determine the intrasession and intersession reliability of isometric force measurements using handheld dynamometry of the knee extensors and flexors and hip abductors in 15 children with cerebral palsy. A secondary purpose was to explore the relationships between muscle forces and standing and walking skills among these subjects. SUBJECTS: Fifteen children with spastic diplegic or quadriplegic cerebral palsy (mean age, 11.7 +/- 3.6 years) participated. METHODS: Two test sessions were separated by four to 14 days. Isometric force production was measured for three muscle groups bilaterally using a handheld dynamometer. Reliability was measured using the intraclass correlation coefficient (ICC 3,1) and the standard error of measurement. The relationship between muscle force values and standing and walking skills [measured with the Gross Motor Function Measure (GMFM), Dimensions D and E] was examined using Pearson's correlation coefficient. RESULTS: Except for left knee flexion, the intrasession and intersession ICCs were 0.84 or greater. The standard errors of measurement ranged from 6.72 to 25.26 N. GMFM Dimensions D and E were positively related to normalized hip abductor force. GMFM Dimension E and the sum of Dimensions D + E were positively related to normalized knee flexor force. CONCLUSION: This group of children with cerebral palsy demonstrated primarily good to high reliability coefficients for isometric force measurements of three lower extremity muscle groups using handheld dynamometry. We suggest that physical therapists use the standard error of measurement for individual clients to help them distinguish measurement error from true changes in muscle force production.