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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. [ABSTRACT FROM AUTHOR]

Background: Knee osteoarthritis(KOA) is the most prevalent type of OA and a leading cause of disability in the United States. Falls are a major public health concern in older adults. Our aim was to examine how the severity of radiographic KOA impacts recurrent falls in a cohort of middle and older aged individuals enrolled in the Osteoarthritis Initiative (OAI).Methods: 3,972 participants, mean age of 63 years, 58% female were included. Participants were divided into 5 mutually exclusive groups based on their worst Kellgren-Lawrence grade of radiographic KOA from annual x-rays from baseline to 36-months. Generalized estimating equations for repeated logistic regression were used to model the association between KOA severity and the likelihood of recurrent falls (≥ 2 falls/year) over 5 years follow-up (>36-96 months).Results: Older adults (≥age 65) with KOA were at higher odds of recurrent falls in comparison to individuals without KOA in multivariate models (possible OA OR= 2.22, 95% CI= 1.09-4.52; mild OA OR=2.48, 95% CI= 1.34-4.62; unilateral moderate-severe OA OR= 2.84, 95% CI= 1.47- 5.50; bilateral moderate-severe OA OR= 2.52, 95% CI= 1.13-5.62). Middle aged adults(age 45-64) with KOA did not have increased odds of recurrent falls in comparison to those without KOA except for possible KOA (OR= 1.86, 95% CI=1.01-2.78) (KOA severity*age interaction = 0.025).Conclusions: Older adults with radiographic evidence of KOA have an increased likelihood of experiencing recurrent falls in comparison to those without KOA independent of established risk factors. Our results suggest fall prevention efforts should include older adults with all stages of KOA. [ABSTRACT FROM AUTHOR]

Background and Objectives Due to health consequences associated with insufficient physical activity (PA), particularly among aging adults, health care providers should assess and address lack of PA participation. Addressing lack of PA means developing individualized PA prescriptions that incorporate solutions to PA participation barriers. Assessing PA participation barriers can be done through the Social Ecological Model-based Inventory of Physical Activity Barriers Scale (IPAB). This study aimed to refine the initial 40-item IPAB and determine its reliability and validity. Research Design and Methods Five hundred and three community-dwelling adults 50 years and older completed a demographic and health questionnaire, the Physical Activity Vital Sign, the IPAB, and a feedback questionnaire. For scale refinement, half of the data were used for exploratory factor analysis and the other half for confirmatory factor analysis. The refined scale underwent reliability and validity assessment, including internal consistency, test–retest reliability, and construct validity. Results The refined scale contains 27 items consisting of 7 factors and 1 stand-alone item: (a) environmental, (b) physical health, (c) PA-related motivation, (d) emotional health, (e) time, (f) skills, (g) social, and (h) energy (a stand-alone item). The 27-item IPAB has good internal consistency (alpha = 0.91) and high test–retest reliability (intraclass correlation coefficient = 0.99). The IPAB's mean scores were statistically different between those who met the recommended levels of PA and those who did not (p <.001). Discussion and Implications The information gathered through the IPAB can guide discussions related to PA participation barriers and develop individualized PA prescriptions that incorporate solutions to the identified barriers. [ABSTRACT FROM AUTHOR]

Background: It is important to understand the factors associated with life-space mobility so that mobility disability can be prevented/treated. The purpose of this study was to identify the association between mobility determinants and life space among older adults.Methods: This study was a cross-sectional analysis of 249 community-dwelling older adults (mean age = 77.4 years, 65.5% female, 88% White), who were recruited for a randomized, controlled, clinical intervention trial. Associations between cognitive, physical, psychosocial, financial, and environmental mobility determinants and the life-space assessment (LSA) at baseline were determined using Spearman's correlation coefficients and one-way analysis of variance. Multivariate analysis was performed using multivariable linear regression models.Results: The mean LSA score for the sample was 75.3 (SD = 17.8). Personal factors (age, gender, education, comorbidities), cognitive (Trail Making Test A and B), physical (gait speed, lower extremity power, 6-Minute Walk Test, Figure of 8 Walk Test, tandem stance, energy cost of walking, and Late-Life Function and Disability Function Scale), psychosocial (Modified Gait Efficacy Scale), and financial (neighborhood socioeconomic status) domains of mobility were significantly associated with LSA score. In the final regression model, age (β = -0.43), lower extremity power (β = 0.03), gait efficacy (β = 0.19), and energy cost of walking (β = -57.41) were associated with life space (R2 = 0.238).Conclusions: Younger age, greater lower extremity power, more confidence in walking, and lower energy cost of walking were associated with greater life space. Clinicians treating individuals with mobility disability should consider personal, physical, and psychosocial factors when assessing barriers to life-space mobility. [ABSTRACT FROM AUTHOR]

Background. Therapeutic activities to improve mobility often include walking practice and exercises to improve defcits in endurance, strength, and balance. Because walking may also be energy inefficient in people with decreased mobility, another approach is to reduce energy cost by improving timing and coordination (TC) of movement. Methods. This pilot randomized trial of older adults with slow and variable gait offered two types of therapeutic activity over 12 weeks. One addressed Walking, Endurance. Balance, and Strength (WEBS) and the other focused on TC. Outcomes were energy cost of walking and measures of mobility. Results. Of 50 participants (mean age. 77.2 [+ or -] 5.5 years, 65% women). 47 completed the study. Baseline gait speed was 0.85 [+ or -] 0.13 m/s and energy cost of walking was 0.30 [+ or -] 0.10 mL/kg/m, nearly twice normal. Both interventions increased gait speed (TC by 0.21 m/s and WEBS by 0.14 m/s. p < .001). TC reduced tile energy cost of walking 0.10 [+ or -] 0.03 mL/ kg/m more than WEBS (p < .001) and reduced the modified Gait Abnormalities Rating Scale 1.5 [+ or -] 0.6 more points than WEBS (p < .05). TC had a 9.8 [+ or -] 3.5 points greater gain than WEBS in self-reported confidence in walking (p < .01). Conclusions. in older adults with slow and variable gait, activity focused on TC reduced the energy cost of walking and improved confidence in walking more than WEBS while generating at least equivalent gains in mobility. To optimize mobility, future larger studies should assess various combinations of TC and WEBS over longer periods of time. Key Words: Exercise--Gait--Energy cost. doi: 10.1093/gerona/glp098

Background. It is unclear if physical activity (PA) can prevent or reverse frailty. We examined different doses and types of PA and their association with the onset and severity of frailty. Methods. Health, Aging and Body Composition (Health ABC) study participants (N = 2,964) were followed for 5 years, with frailty defined as a gait speed of less than 0.60 m/s and/or inability to rise from a chair without using one's arms. Individuals with one impairment were considered moderately frail and those with both severely frail. We examined PA doses of volume and intensity, activity types (eg, lifestyle vs exercise activities), and their associations with incident frailty and transition to severe frailty in those who became frail. Results. Adjusted models indicated that sedentary individuals had significantly increased odds of developing frailty compared with the exercise active group (adjusted odds ratio [OR] = 1.45; 95% confidence interval [CI]: 1.04-2.01), whereas the lifestyle active did not. Number of diagnoses was the strongest predictor of incident frailty. In those who became frail during follow-up (n = 410), there was evidence that the sedentary (adjusted OR = 2.80; 95% CI: 0.98-8.02) and lifestyle active (adjusted OR = 2.81; 95% CI: 1.22-6.43) groups were more likely to have worsening frailty over time. Conclusions. Despite the strong relationship seen between comorbid conditions and onset of frailty, this observational study suggests that participation in self-selected exercise activities is independently associated with delaying the onset and the progression of frailty. Regular exercise should be further examined as a potential factor in frailty prevention for older adults. Key Words: Aging--Exercise--Frail elderly--Longitudinal studies.

Background. Gait speed is a strong predictor of incident walking disability. The objective was to determine if gait variability adds to the prediction of incident mobility disability independent of gait speed. Methods. Participants included 379 older adults (mean age = 79 years; 78% Caucasian, and 40% men) in the Cardiovascular Health Study at the Pittsburgh site. All could ambulate independently and reported no difficulty walking a half mile. Gait characteristics were determined from a 4-meter computerized walkway. For each gait parameter, variability was defined as the standard deviation from the individual steps from two passes. Incident walking disability was obtained by phone interview every 6 months for 54 months and was defined as new difficulty walking a half mile or inability to walk a half mile. Results. Of the 379 participants, 222 (58.6%) developed incident mobility disability. In unadjusted Cox proportional hazards models gait speed, mean step length, mean stance time, and stance time variability were associated with incident mobility disability. After adjusting for gait speed, demographics, chronic conditions, prescription medications, health status, and physical activity level, only stance time variability remained an important indicator of disability. In the adjusted model, an increase in stance time variability of 0.01 seconds was associated with a 13% higher incidence of mobility disability (hazard ratio 1.13, 95% confidence interval, 1.01-1.27). Conclusions. Stance time variability is an independent predictor of future mobility disability. Future efforts are needed to determine whether interventions that decrease stance time variability will also delay mobility disability.

A study to demonstrate that the ability to walk 400 m and timed performance discriminate mortality and cardiovascular risk and risk for mobility limitation and disability in community dwelling older adults without known difficulty performing mobility-related tasks is illustrated. The findings provide validation of the importance of having the capacity to walk longer distances and show that there is a wide range of function and risk in apparently well-functioning older adults.

Background. Biologic changes are expected to occur prior to disability. Compared with physical disability measures, measures of muscle impairment may be an earlier indicator of functional decline. The purpose of this study was to describe a new approach of measuring muscle impairment during a functional task. Methods. Right quadriceps muscle activity was recorded using surface electromyography (sEMG) from 160 older women (age 73.9 [+ or -] 3.9 years, mean [+ or -] SD). Specific patterns of muscle activity during the chair stand task were determined using an exploratory principal components factor analysis (PCFA). Muscle activity parameters were validated by comparison to the Physical Performance Test, gait speed, and the Functional Status Questionnaire. Results. The PCFA indicated two factors (magnitude and timing) that represented important components of quadriceps muscle activity during chair stand, explaining 68.6% of the variance in performance. The slope of the rise of muscle activity represents a combination of the magnitude and timing components of muscle activity. Compared with women with a slope < 1, women with a slope [is greater than or equal to] 1 walked faster (1.17 m/s vs 1.09 m/s; p = .02) find reported less difficulty with activities of daily living (ADL) (98.6 vs 95.8; p = .003) and instrumental ADL (97.3 vs 92.2; p = .001). Conclusions. Quadriceps muscle activity recorded during chair stand is a valid and reliable measure of muscle performance during a functional task. As a biologic measure of muscle activation, sEMG may identify muscle impairment, which could indicate functional decline earlier than measures of functional status.