Prefrontal cortex activation while walking did not change but gait speed improved after a randomized physical therapy intervention.

BACKGROUND: Higher prefrontal cortex (PFC) activation while walking may indicate reduced gait automaticity. AIM: We examine whether PFC activation during walking improves after training in older adults at risk for mobility disability. METHODS: Forty-two adults aged ≥ 65 participated in a randomized clinical trial (NCT026637780) of a 12-week timing and coordination physical therapy intervention to improve walking (n = 20 intervention, n = 22 active control). PFC activation was measured by functional near-infrared spectroscopy (fNIRS) during four walking tasks over 15 m, each repeated 4 times: even surface walking, uneven surface walking, even dual-task, uneven dual-task; dual-task was reciting every other letter of the alphabet while walking. Gait speed and rate of correct letter generation were recorded. Linear mixed models tested between arm differences in change of fNIRS, gait speed, and letter generation from baseline to follow-up (12-week, 24-week, and 36-week). RESULTS: Intervention arms were similar in mean age (74.3 vs. 77.0) and baseline gait speed (0.96 vs. 0.93 m/s). Of 24 comparisons of between arm differences in the fNIRS signals, only two were significant which were not supported by differences at other follow-up times or on other tasks. Gait speed, particularly during dual-task conditions, and correct letter generation did improve post-intervention but improvements did not differ by arm. DISCUSSION AND CONCLUSIONS: After training, PFC activation during walking generally did not improve and did not differ by intervention arm. Improvements in gait speed without increased PFC activation may point toward more efficient neural control of walking.

Prevalence and Predictors of Ambulatory Care Physicians' Documentation of Mobility Limitations in Older Adults.

OBJECTIVE: To determine how often physicians document mobility limitations in visits with older adults, and which patient, physician, and practice characteristics associate with documented mobility limitations. DESIGN: We completed a cross-sectional analysis of National Ambulatory Medical Care Surveys, years 2012-2016. Multivariate analyses were conducted to identify patient, physician, and practice-level factors associated with mobility limitation documentation. SETTING: Ambulatory care visits. PARTICIPANTS: We analyzed visits with adults 65 years and older. Final sample size represented 1.3 billion weighted visits. INTERVENTION: Not applicable. MAIN OUTCOME MEASURE: We defined the presence/absence of a mobility limitation by whether any International Classification of Diseases (ICD)-9 or ICD-10 code related to mobility limitations, injury codes, or the patient's "reasons for visit" were documented in the visits. RESULTS: The overall prevalence of mobility limitation documentation was 2.4%. The most common codes were falls-related. Patient-level factors more likely to be associated with mobility limitation documentation were visits by individuals over 85 years of age, relative to 65-69 years, (odds ratio 2.32, 95% confidence interval 1.76-3.07]; with a comorbid diagnosis of arthritis (odds ratio 1.35, 1.18-2.01); and with a comorbid diagnosis of cerebrovascular disease (odds ratio 1.60, 1.13-2.26). Patient-level factors less likely to be associated with mobility limitation documentation were visits by men (odds ratio 0.80, 0.64-0.99); individuals with a cancer diagnosis (odds ratio 0.76, 0.58-0.99); and by individuals seeking care for a chronic problem (relative to a new problem [odds ratio 0.36, 0.29-0.44]). Physician-level factors associated with an increased likelihood of mobility limitation documentation were visits to neurologists (odds ratios 4.48, 2.41-8.32) and orthopedists (odds ratio 2.67, 1.49-4.79) compared with primary care physicians. At the practice-level, mobility documentation varied based on the percentage of practice revenue from Medicare. CONCLUSIONS: Mobility limitations are under-documented and may be primarily captured when changes in function are overt.

Bidirectional associations of accelerometer-derived physical activity and stationary behavior with self-reported mental and physical health during midlife.

BACKGROUND: Moderate-to-vigorous intensity physical activity (MVPA) is associated with favorable self-rated mental and physical health. Conversely, poor self-rated health in these domains could precede unfavorable shifts in activity. We evaluated bidirectional associations of accelerometer-estimated time spent in stationary behavior (SB), light intensity physical activity (LPA), and MVPA with self-rated health over 10 years in in the CARDIA longitudinal cohort study. METHODS: Participants (n = 894, age: 45.1 ± 3.5; 63% female; 38% black) with valid accelerometry wear and self-rated health at baseline (2005-6) and 10-year follow-up (2015-6) were included. Accelerometry data were harmonized between exams and measured mean total activity and duration (min/day) in SB, LPA, and MVPA; duration (min/day) in long-bout and short-bout SB (≥30 min vs. < 30 min) and MVPA (≥10 min vs. < 10 min) were also quantified. The Short-Form 12 Questionnaire measured both a mental component score (MCS) and physical component score (PCS) of self-rated health (points). Multivariable linear regression associated baseline accelerometry variables with 10-year changes in MCS and PCS. Similar models associated baseline MCS and PCS with 10-year changes in accelerometry measures. RESULTS: Over 10-years, average (SD) MCS increased 1.05 (9.07) points, PCS decreased by 1.54 (7.30) points, and activity shifted toward greater SB and less mean total activity, LPA, and MVPA (all p < 0.001). Only baseline short-bout MVPA was associated with greater 10-year increases in MCS (+ 0.92 points, p = 0.021), while baseline mean total activity, MVPA, and long-bout MVPA were associated with greater 10-year changes in PCS (+ 0.53 to + 1.47 points, all p < 0.005). In the reverse direction, higher baseline MCS and PCS were associated with favorable 10-year changes in mean total activity (+ 9.75 cpm, p = 0.040, and + 15.66 cpm, p < 0.001, respectively) and other accelerometry measures; for example, higher baseline MCS was associated with - 13.57 min/day of long-bout SB (p < 0.001) and higher baseline PCS was associated with + 2.83 min/day of MVPA (p < 0.001) in fully adjusted models. CONCLUSIONS: The presence of bidirectional associations between SB and activity with self-rated health suggests that individuals with low overall activity levels and poor self-rated health are at high risk for further declines and supports intervention programming that aims to dually increase activity levels and improve self-rated health.

Psychometric properties of instrumented postural sway measures recorded in community settings in independent living older adults.

BACKGROUND: In the last few decades, research related to balance in older adults has been conducted in lab-based settings. The lack of portability and high cost that is associated with the current gold standard methods to quantify body balance limits their application to community settings such as independent living facilities. The purpose of the study was to examine the relative and absolute reliability and the convergent validity of static standing balance performance using an accelerometer device. METHODS: A total of 131 participants (85% female, mean age 80 ± 8 years) were included for the validity aim, and a subsample of 38 participants were enrolled in the reliability testing (89% female, mean age 76 ± 7 years). The root-mean-square (RMS) and normalized path length (NPL) for sway in antero-posterior (AP) and medio-lateral (ML) directions were calculated for different standing balance conditions. Test-retest reliability was assessed over two testing visits occurring 1 week apart using the intraclass correlation coefficient (ICC) for relative reliability, and the minimal detectable change (MDC) was calculated for the absolute reliability. Spearman's rank correlation coefficient was used to test convergent validity at baseline between balance measurements and related mobility measures. RESULTS: Reliability of balance performance using accelerometers was good to excellent with ICC values ranging from 0.41 to 0.83 for RMS sway and from 0.49 to 0.82 for NPL sway. However, the ICC during semi-tandem stance in A-P direction was 0.35, indicating poor reliability. The MDC of the sway measurements ranged from 2.4 to 9.4 for the RMS and 5.2 to 13.8 for the NPL. Balance measurements were correlated with mobility measurements. CONCLUSIONS: Using a portable accelerometer to quantify static standing postural control provides reliable measurements in community settings.

Potential long-term impact of "On The Move" group-exercise program on falls and healthcare utilization in older adults: an exploratory analysis of a randomized controlled trial.

BACKGROUND: Wellness program participation may reduce the risk of falling, emergency department-use, and hospitalization among older adults. "On the Move" (OTM), a community-based group exercise program focused on the timing and coordination of walking, improved mobility in older adults, but its impact on falls, emergency department-use, and hospitalizations remains unclear. The aim of this preliminary study was to investigate the potential long-term effects that OTM may have on downstream, tertiary outcomes. METHODS: We conducted a secondary analysis of a cluster-randomized, single-blind intervention trial, which compared two community-based, group exercise programs: OTM and a seated exercise program on strength, endurance, and flexibility (i.e. 'usual-care'). Program classes met for 50 min/session, 2 sessions/week, for 12 weeks. Older adults (≥65 years), with the ability to ambulate independently at ≥0.60 m/s were recruited. Self-reported incidence of falls, emergency department visitation, and hospitalization were assessed using automated monthly phone calls for the year following intervention completion. Participants with ≥1 completed phone call were included in the analyses. Incidence rate ratios (IRRs) and 95% confidence intervals (CIs) were calculated (reference = usual-care). RESULTS: Participants (n = 248) were similar on baseline characteristics and number of monthly phone calls completed. Participants in the seated exercise program attended an average of 2.9 more classes (p = .017). Of note, all results were not statistically significant (i.e. 95% CI overlapped a null value of 1.0). However, point estimates suggest OTM participation resulted in a decreased incidence rate of hospitalization compared to usual-care (IRR = 0.88; 95% CI = 0.59-1.32), and the estimates strengthened when controlling for between-group differences in attendance (adjusted IRR = 0.82; 95% CI = 0.56-1.21). Falls and emergency department visit incidence rates were initially greater for OTM participants, but decreased after controlling for attendance (adjusted IRR = 1.08; 95% CI = 0.72-1.62 and adjusted IRR = 0.96; 95% CI = 0.55-1.66, respectively). CONCLUSION: Compared to a community-based seated group exercise program, participation in OTM may result in a reduced risk of hospitalization. When OTM is adhered to, the risk for falling and hospitalizations are attenuated. However, definitive conclusions cannot be made. Nevertheless, it appears that a larger randomized trial, designed to specifically evaluate the impact of OTM on these downstream health outcomes is warranted. TRIAL REGISTRATION: Clinical trials.gov (NCT01986647; prospectively registered on November 18, 2013).

Psychometric Properties of Lower Extremity Strength Measurements Recorded in Community Settings in Independent Living Older Adults.

BACKGROUND: A uniaxial load cell device provides an alternative, easy and inexpensive way to quantify muscle strength in different settings outside the clinic and research labs. So, the purpose of the study was to examine the test-retest reliability and the construct validity of lower extremity strength performance using an uniaxial load cell device. METHODS: A total of 131 subjects (85% female, mean age 80 ± 8 years) were included for the validity aim, and a sample of 38 subjects were enrolled in the reliability testing (89% female, mean age 76 ± 7 years). For the strength measurements were assessed with a portable load cell for three consecutive trials. Test-retest reliability was assessed over two testing visits occurring one week apart. Spearman's rank correlation coefficient was used to test convergent validity with other mobility-related measurements construct validity at baseline. RESULTS: Strength measurements showed good to excellent reliability in most of the measured parameters with intraclass correlation coefficients range from 0.89 to 0.99 and were correlated with mobility measurements with Spearman rho range from 0.21 to 0.38. CONCLUSION: The portable uni-axial load cell to measure lower extremity strength provides reliable measurements in community settings.

Accuracy and Acceptability of Commercial-Grade Physical Activity Monitors in Older Adults.

The aim of this study was to evaluate accuracy of seven commercial activity monitors in measuring steps in older adults with varying walking abilities and to assess monitor acceptability and usability. Forty-three participants (age = 87 ± 5.7 years) completed a gait speed assessment, two walking trials while wearing the activity monitors, and questionnaires about usability features and activity monitor preferences. The Accusplit AX2710 Accelerometer Pedometer had the highest accuracy (93.68% ± 13.95%), whereas the Fitbit Charge had the lowest (39.12% ± 40.3%). Device accuracy varied based on assistive device use, and none of the monitors were accurate at gait speeds <0.08 m/s. Barriers to monitor usability included inability to apply monitor and access the step display. Monitor accuracy was rated as the most important feature, and ability to interface with a smart device was the least important feature. This study identified the limitations of the current commercial activity monitors in both step counting accuracy and usability features for older adults.

The Role of the Environment on Sedentary Behavior in Community-Dwelling Older Adults.

OBJECTIVES: To compare amounts of sedentary behavior and physical activity in adults residing in planned group residential settings to those residing in private homes. METHODS: Thirty-one older adults who resided in planned group residential settings (n=13) and in private homes (n=18) participated. Daily activities were measured using the Sensewear Armband for 7 days. Estimates of the duration of daily activities performed across sedentary, light, and moderate-to-vigorous intensities were captured. RESULTS: Participants in planned group residential settings were older (age 85.9±3.5 vs 78.3±7.2; p=0.001) and spent more time in sedentary behaviors (12.7±1.5 vs 11.3±1.6; p=0.02) than participants in private homes. The difference was attenuated slightly after controlling for age and wear time (adjusted difference 1.2±0.6 hours, p=0.06). DISCUSSION: Adults residing in planned group residential settings, which provide supportive services, were more sedentary than adults residing in private homes. The environment in which older adults live may contribute to sedentary behavior.

Improving motor control in walking: a randomized clinical trial in older adults with subclinical walking difficulty.

OBJECTIVE: To test the proposed mechanism of action of a task-specific motor learning intervention by examining its effect on measures of the motor control of gait. DESIGN: Single-blinded randomized clinical trial. SETTING: University research laboratory. PARTICIPANTS: Adults (N=40) aged ≥65 years with gait speed >1.0m/s and impaired motor skill (figure-of-8 walk time >8s). INTERVENTIONS: The 2 interventions included a task-oriented motor learning and a standard exercise program; both interventions included strength training. Both lasted 12 weeks, with twice-weekly, 1-hour, physical therapist-supervised sessions. MAIN OUTCOME MEASURES: Two measures of the motor control of gait, gait variability and smoothness of walking, were assessed pre- and postintervention by assessors masked to the treatment arm. RESULTS: Of 40 randomized subjects, 38 completed the trial (mean age ± SD, 77.1±6.0y). The motor learning group improved more than the standard group in double-support time variability (.13m/s vs .05m/s; adjusted difference [AD]=.006, P=.03). Smoothness of walking in the anteroposterior direction improved more in the motor learning than standard group for all conditions (usual: AD=.53, P=.05; narrow: AD=.56, P=.01; dual task: AD=.57, P=.04). Smoothness of walking in the vertical direction also improved more in the motor learning than standard group for the narrow-path (AD=.71, P=.01) and dual-task (AD=.89, P=.01) conditions. CONCLUSIONS: Among older adults with subclinical walking difficulty, there is initial evidence that task-oriented motor learning exercise results in gains in the motor control of walking, while standard exercise does not. Task-oriented motor learning exercise is a promising intervention for improving timing and coordination deficits related to mobility difficulties in older adults, and needs to be evaluated in a definitive larger trial.

The Test-Retest Reliability of Indirect Calorimetry Measures of Energy Expenditure During Overground Walking in Older Adults With Mobility Limitations.

The purpose of this study was to assess the relative and absolute reliability of metabolic measures of energy expenditure and gait speed during overground walking in older adults with mobility limitations. Thirty-three (mean age [SD] = 76.4 [6.6] years; 66% female) older adults with slow gait participated. Measures of energy expenditure and gait speed were recorded during two 6-min bouts of overground walking (1 week apart) at a self-selected "usual" walking pace. The relative reliability for all variables was excellent: ICC = .81-.91. Mean differences for five of the six outcome variables was less than or equal to the respected SEM, while all six mean differences fell below the calculated MDC95. Clinicians and researchers can be confident that metabolic measures of energy expenditure and gait speed in older adults with slow walking speeds can be reliably assessed during overground walking, providing an alternative to traditional treadmill assessments.

Activity and Participation Are Associated with Future Falls, Hospitalizations, and Emergency Visits in Community-Dwelling Older Adults.

OBJECTIVE: Activity and participation are important for older adults as they are associated with well-being and quality of life. Falls, emergency department (ED) visits, and hospitalizations are adverse health outcomes that impact older adults. Limited research has investigated whether measurement of activity and participation are related to adverse health events in community dwelling older adults. This study sought to examine the association between activity and participation with falls, ED visits, and hospitalization over 1 year in community dwelling older adults. METHODS: A secondary analysis of a longitudinal clinical trial of 341 community dwelling older adults was conducted. The sample mean age was 80.9 (SD = 7.7) years and 83% were female. One-year risk of falls was associated with baseline Late Life Function and Disability Instrument (LLFDI) components of overall function and disability (frequency and limitations dimensions). Incident rate ratios (IRRs) and 95% CIs were calculated. RESULTS: For each 5-point higher score (clinically meaningful difference) in activity as measured by LLFDI-overall function (adjusted for age, race, sex, comorbidities and fall history), there was an 18% lower rate of falls (IRR = 0.82, 95% CI = 0.74-0.92); 12% reduction in hospitalizations (IRR = 0.88; 95% CI = 0.77-0.99); and 11% lower rate of emergency room visits (IRR = 0.89, 95% CI = 0.81-0.98). Greater participation as measured by the LLFDI limitations dimension was related to fewer falls (IRR = 0.93, 95% CI = 0.87-1.00) and hospitalizations (IRR = 0.91, 95% CI = 0.83-0.99). CONCLUSION: Greater activity and participation are associated with a lower incidence of falls, ED visits, and hospitalizations representing an important consideration for targeted physical therapist interventions. IMPACT STATEMENT: Physical therapists are uniquely positioned to identify and address reduced activity and participation. If activity and participation are specifically targeted and improved through physical therapy, undesirable distal health outcomes might be prevented or minimized.

Greater activity and participation were found to be related to lower rate of falls, ED visits, and hospitalizations in a sample of 341 older adults who lived in the community.

On the move in the community: Protocol for a hybrid 1 trial examining effectiveness and fidelity of a community-based group exercise program for older adults.

BACKGROUND: On the Move (OTM), a group exercise program to improve mobility in older adults, is efficacious when delivered by research staff. The next step in the development of OTM as a fully implementable intervention is to conduct an effectiveness study in which the intervention is delivered in community settings by community providers. METHODS: We describe the methods of a hybrid 1 cluster randomized, single-blind, intervention trial to compare the effectiveness of OTM to a delayed intervention control in 502 community-dwelling older adults across 44 sites. OTM classes are taught by certified instructors in the community twice a week for 12 weeks. Control centers receive no intervention for the first 12 weeks followed by 12-weeks of OTM classes. Participants are assessed at baseline, 12 and 24 weeks. The primary outcome is gait speed. Intervention fidelity, measured by adherence and competence in intervention delivery, is assessed by review of instructor intervention diaries and observation. Organizational, instructor, and participant-level factors which may impact fidelity are assessed using questionnaires, focus groups, and structured interviews. CONCLUSION: The findings of this trial will 1) establish the effectiveness of OTM on improvements in walking and post-intervention persistence of benefits, 2) assess intervention fidelity and identify the impact of organizational, instructor, and participant level factors on fidelity, and 3) determine the extent to which fidelity moderates the effectiveness of OTM. The information derived from this project will provide valuable insight into the real-world effectiveness of OTM as a health promotion program for improving mobility in older adults.

Global Positioning System Indicators of Community Mobility and Future Health Outcomes Among Older Adults.

BACKGROUND: We examined the relationship between global positioning system (GPS) indicators of community mobility and incident hospitalizations, emergency department (ED) visits, and falls over 1-year in community-dwelling older adults. METHODS: We performed a secondary analysis of a randomized trial investigating a physical therapy intervention to improve mobility in older adults. One hundred and forty-eight participants (mean age: 76.9 ±â€…6.2 years; 65% female) carried a GPS device following the postintervention visit. Over 1-year, new hospitalizations, falls, and ED visits were reported. GPS indicators of community mobility included the median area and compactness of the standard deviation ellipse (SDE), the median percentage of time spent outside of home (TOH), and median maximum distance from home. Generalized linear models assessed the association between 1-year risk of outcomes and GPS measures adjusted for age, race, gender, body mass index, comorbidity burden, and fall history. RESULTS: The mean ±â€…standard deviation of the median SDE area was 4.4 ±â€…8.5 km2, median SDE compactness 0.7 ±â€…0.2, median percentage TOH 14.4 ±â€…12.0%, and median maximum distance from home was 38 ±â€…253 km. Each 5% increase in median percentage TOH was associated with a 24% lower risk of hospitalization (incident rate ratio = IRR = 0.76, 95%CI: 0.61-0.95; p = .01). The association persisted after covariate adjustment (IRR = 0.78, 95%CI: 0.63-0.98; p = .03). No significant associations appeared for any GPS indicators with incident falls or ED visits. CONCLUSIONS: Increased TOH was associated with a lower risk of incident hospitalization over 1 year among community-dwelling older adults. Restricted community mobility may be an indicator of activity limitations related to future health outcomes, but further study is warranted.

Feasibility and Preliminary Efficacy of Virtual Rehabilitation for Middle and Older Aged Veterans With Mobility Limitations: A Pilot Study.

Objective: To evaluate the feasibility and preliminary efficacy of the transition of an outpatient center-based rehabilitation program for middle and older aged Veterans with mobility limitations to a tele-health platform. Design: Non-randomized non-controlled pilot study including 10 treatment sessions over 8 weeks and assessments at baseline, 8, 16, and 24 weeks. Setting: VA Boston Healthcare System ambulatory care between August 2020 and March 2021. Participants: Veterans aged 50 years and older (n=178) were contacted via letter to participate, and 21 enrolled in the study. Intervention: Participants had virtual intervention sessions with a physical therapist who addressed impairments linked to mobility decline and a coaching program promoting exercise adherence. Main Outcome Measures: Ambulatory Measure for Post-Acute Care (AM-PAC), Phone-FITT, and Self-Efficacy for Exercise (SEE) scale. Results: Completers (n=14, mean age 74.9 years, 86% men) averaged 9.8 out of 10 visits. Changes in the Ambulatory Measure for Post-Acute Care (AM-PAC) exceeded clinically meaningful change after 8 and 24 weeks of treatment, at 4.1 units and 4.3 units respectively. Statistically significant improvements from baseline in AM-PAC and Phone-FITT were observed after 8 weeks of treatment and at 24 weeks. No significant changes were observed in exercise self-efficacy. Conclusions: In this group of veterans, telerehab was feasible and demonstrated preliminary efficacy in both mobility and physical activity, thus justifying further investigation in a larger scale clinical trial.

Neighborhood Walkability Is Associated With Global Positioning System-Derived Community Mobility of Older Adults.

BACKGROUND: Neighborhood walkability may encourage greater out-of-home travel (ie, community mobility) to support independent functioning in later life. We examined associations between a novel walkability audit index and Global Positioning System (GPS)-derived community mobility in community-dwelling older adults. We compared associations with the validated Environmental Protection Agency (EPA) National Walkability Index and further examined moderation by clinical walking speed. METHODS: Participants were 146 older adults (Mean = 77.0 ±â€…6.5 years, 68% women) at baseline of a randomized trial to improve walking speed. A walkability index (range: 0-5; eg, land-use mix, crosswalks, and so on) was created using Google Street View audits within 1/8-mile of the home. Participants carried a GPS device for 5-7 days to derive objective measures of community mobility (eg, time spent out of home, accumulated distance from home). RESULTS: Each 1 SD (~1.3-point) greater walkability audit score was associated with a median 2.16% more time spent out of home (95% confidence interval [95% CI]: 0.30-4.03, p = .023), adjusting for individual demographics/health and neighborhood socioeconomic status. For slower walkers (4-m walking speed <1 m/s), each 1 SD greater audit score was also associated with a median 4.54 km greater accumulated distance from home (95% CI: 0.01-9.07, p (interaction) = .034). No significant associations were found for the EPA walkability index. CONCLUSIONS: Walkability immediately outside the home was related to greater community mobility, especially for older adults with slower walking speeds. Results emphasize the need to consider the joint influence of local environment and individual functioning when addressing community mobility in older populations.

Fear of falling in community-dwelling older adults: What their gait acceleration pattern reveals.

BACKGROUND: Fear of Falling (FOF) is common among community-dwelling older adults and is associated with increased fall-risk, reduced activity, and gait modifications. OBJECTIVE: In this cross-sectional study, we examined the relationships between FOF and gait quality. METHODS: Older adults (N=232; age 77±6; 65 % females) reported FOF by a single yes/no question. Gait quality was quantified as (1) harmonic ratio (smoothness) and other time-frequency spatiotemporal variables from triaxial accelerometry (Vertical-V, Mediolateral-ML, Anterior-Posterior -AP) during six-minute walk; (2) gait speed, step-time CoV (variability), and walk-ratio (step-length/cadence) on a 4-m instrumented walkway. Mann Whitney U-tests and Random forest classifier compared gait between those with and without FOF. Selected gait variables were used to build Support Vector Machine (SVM) classifier and performance was evaluated using AUC-ROC. RESULTS: Individuals with FOF had slower gait speed (103.66 ± 17.09 vs. 110.07 ± 14.83 cm/s), greater step time CoV (4.17 ± 1.66 vs. 3.72 ± 1.24 %), smaller walk-ratio (0.53 ± 0.08 vs. 0.56 ± 0.07 cm/steps/minute), smaller standard deviation V (0.15 ± 0.06 vs. 0.18 ± 0.09 m/s2), and smaller harmonic-ratio V (2.14 ± 0.73 vs. 2.38 ± 0.58), all p<.01. Linear SVM yielded an AUC-ROC of 67 % on test dataset, coefficient values being gait speed (-0.19), standard deviation V (-0.23), walk-ratio (-0.36), and smoothness V (-0.38) describing associations with presence of FOF. CONCLUSION: Older adults with FOF have reduced gait speed, acceleration adaptability, walk-ratio, and smoothness. Disrupted gait patterns during fear of falling could provide insights into psychosocial distress in older adults. Longitudinal studies are warranted.

Association of Gait Quality With Daily-Life Mobility: An Actigraphy and Global Positioning System Based Analysis in Older Adults.

OBJECTIVE: Walking is a key component of daily-life mobility. We examined associations between laboratory-measured gait quality and daily-life mobility through Actigraphy and Global Positioning System (GPS). We also assessed the relationship between two modalities of daily-life mobility i.e., Actigraphy and GPS. METHODS: In community-dwelling older adults (N = 121, age = 77±5 years, 70% female, 90% white), we obtained gait quality from a 4-m instrumented walkway (gait speed, walk-ratio, variability) and accelerometry during 6-Minute Walk (adaptability, similarity, smoothness, power, and regularity). Physical activity measures of step-count and intensity were captured from an Actigraph. Time out-of-home, vehicular time, activity-space, and circularity were quantified using GPS. Partial Spearman correlations between laboratory gait quality and daily-life mobility were calculated. Linear regression was used to model step-count as a function of gait quality. ANCOVA and Tukey analysis compared GPS measures across activity groups [high, medium, low] based on step-count. Age, BMI, and sex were used as covariates. RESULTS: Greater gait speed, adaptability, smoothness, power, and lower regularity were associated with higher step-counts (0.20<|ρp| < 0.26, p < .05). Age(ß = -0.37), BMI(ß = -0.30), speed(ß = 0.14), adaptability(ß = 0.20), and power(ß = 0.18), explained 41.2% variance in step-count. Gait characteristics were not related to GPS measures. Participants with high (>4800 steps) compared to low activity (steps<3100) spent more time out-of-home (23 vs 15%), more vehicular travel (66 vs 38 minutes), and larger activity-space (5.18 vs 1.88 km2), all p < .05. CONCLUSIONS: Gait quality beyond speed contributes to physical activity. Physical activity and GPS-derived measures capture distinct aspects of daily-life mobility. Wearable-derived measures should be considered in gait and mobility-related interventions.

Associations of Neurological Biomarkers in Serum With Gait Measures: The Cardiovascular Health Study.

BACKGROUND: Gait impairment leads to increased mobility decline and may have neurological contributions. This study explores how neurological biomarkers are related to gait in older adults. METHODS: We studied participants in the Cardiovascular Health Study, a population-based cohort of older Americans, who underwent a serum biomarker assessment from samples collected in 1996-1997 for neurofilament light chain (NfL), glial fibrillary acidic protein, ubiquitin carboxy-terminal hydrolase L1, and total tau (n = 1 959, mean age = 78.0 years, 60.8% female). In a subsample (n = 380), cross-sectional associations with quantitative gait measures were explored. This subsample was assessed on a mat for gait speed, step length, double support time, step time, step length variability, and step time variability. Gait speed was also measured over a 15-ft walkway annually from 1996-1997 to 1998-1999 for longitudinal analyses. Linear regression models assessed cross-sectional associations of biomarkers with gait measures, whereas mixed effects models assessed longitudinal gait speed change from baseline to 1998-1999. RESULTS: Neurofilament light chain was significantly associated with annual gait speed decline (standardized ß = -0.64 m/s, 95% CI: [-1.23, -0.06]) after adjustment for demographic and health factors. Among gait mat-assessed phenotypes, NfL was also cross-sectionally associated with gait speed (ß = 0.001 m/s [0.0003, 0.002]) but not with other gait measures. None of the remaining biomarkers were significantly related to gait in either longitudinal or cross-sectional analyses. CONCLUSIONS: Higher NfL levels were related to greater annual gait speed decline. Gait speed decline may be related to axonal degeneration. The clinical utility of NfL should be explored.

What is the relation between fear of falling and physical activity in older adults?

OBJECTIVE: To describe the association between fear of falling (FOF) and total daily activity in older adults. DESIGN: Cross-sectional observational study. SETTING: Ambulatory clinical research training center. PARTICIPANTS: Community-dwelling older adults aged ≥64 years (N=78), who were independent in ambulation with or without an assistive device. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: FOF was defined by self-reported fear ratings using the Survey of Activities and Fear of Falling in the Elderly and self-reported fear status determined by response to the following question: Are you afraid of falling? Physical function was assessed using the Late Life Function and Disability Instrument. Physical activity was recorded using an accelerometer worn on the waist for 7 consecutive days, and mean daily counts of activity per minute were averaged over the 7-day period. RESULTS: Fear ratings were related to total daily activity (r=-.26, P=.02). The relation was not as strong as the relation of function and physical activity (r=.45, P<.001). When stratified by exercise status or functional status, fear was no longer related to total daily activity. Physical function explained 19% of the variance in physical activity, whereas the addition of fear status did not add to the explained variance in physical activity. CONCLUSIONS: FOF is related to total daily physical activity; however, FOF was not independently associated with physical activity when accounting for physical function. Some FOF may be reported as a limitation in function.