Risk Of Mobility Disability Research Articles

Multidimensional Benefits of Weight Management in Old Age: The Mobility and Vitality Lifestyle Program

The high prevalence of overweight or obesity in older adults is a public health concern because obesity is associated with risk of mobility disability. The benefits of brief community-based lifestyle interventions that promote modest weight loss and increased physical activity are unclear. We assessed the impact of a 13-month lifestyle intervention, the Mobility and Vitality Lifestyle Program (MOVE UP), delivered by community health workers (CHW), on a variety of outcomes, including weight loss, performance-based lower extremity function (Short Physical Performance Battery, SPPB), activity, diet, and health-related quality of life (CDC U48 DP005001). The 32-session behavioral weight management intervention enrolled 303 community-dwelling adults (90.4% of those eligible), who were followed for 12 months (2015-19). Participants completed the program at 26 sites led by 22 CHWs. Participants were age (sd) 67.7 (4.1) and were mostly female (87%). 22.7% were racial minorities. The mean (sd) BMI at baseline was 34.7 (4.7). Median weight loss in the sample was 5% of baseline body weight. SPPB total scores improved by +0.31 units (p < .006), gait speed by +0.04 m/sec (p < .0001), and time to complete chair stands by -0.95 sec (p < .0001). Presenters will assess the effect of MOVE UP on activity, diet, fatigue, and health-related quality of life. A final paper examines implementation of MOVE UP and how site and CHW factors affected outcomes. Findings suggest that promoting healthier eating, weight loss, and physical activity in a community setting is an effective strategy for reducing risk of disability in older adults.

Higher relative effort of the knee relates to faster adaptation in older adults at risk for mobility disability.

Gait adaptation is crucial for adults at risk for mobility disability, and executive function and physical function may be important for adaptation performance. Gait adaptation can be measured using a treadmill with two belts, known as a split-belt treadmill. Increasing evidence supports that gait adaptability, executive function, and physical function are interrelated in older adults. The purpose of this study was to determine if: a) executive function and measures of relative effort of the ankle and knee relate to split-belt treadmill adaptation; b) older adults classified as fast adapters display differences in relative effort, executive function, and propulsive impulse (push-off) compared to slow adapters; and c) spatial and temporal control differ between individuals with faster rate of adaptation compared to those with slower rates of adaptation. Greater effort of the knee on the slow belt was related to faster early adaptation (r=0.650, p=0.005) indicating its importance for adapting quickly to the perturbation. We did not observe a relationship between cognitive tests and adaptation performance. We did not detect any statistical differences in cognitive tests performance, push-off, spatial or temporal control between fast adapters compared to slow adapters. Our results suggest that in older adults at risk for mobility disability, higher effort at the knee is important for early split-belt adaptation.

Impact of Low Muscle Mass and Low Muscle Strength According to EWGSOP2 and EWGSOP1 in Community-Dwelling Older People.

A universal definition of sarcopenia is still lacking. Since the European criteria have been recently revised, we aimed at studying prevalence of low muscle strength (LMS) and low muscle mass (LMM), as defined according to the European Working Group of Sarcopenia in Older People (EWGSOP) 2 and 1 definitions, and their individual contribution toward mortality and incident mobility disability in a cohort of community-dwelling older people. Longitudinal analysis of 535 participants of the InCHIANTI study. LMS and LMM were defined according to the criteria indicated in the EWGSOP2 and 1. Cox and log-binomial regressions were used to examine association with mortality and 3-year mobility disability (inability to walk 400 m). We observed a lower prevalence of the combination LMM/LMS according to EWGSOP2 compared to EWGSOP1 (3.2% vs 6.2%). Using the new criteria, all sarcopenia components were associated with mortality, although the hazard ratio [HR] for the group LMM/LMS was no longer significant after adjustment for confounders (LMM: HR 2.69, 95% confidence interval [CI] 1.04-6.94; LMS: HR 3.18, 95% CI 1.44-7.01; LMM/LMS: HR 2.95, 95% CI 0.86-10.16). Using EWGSOP1, LMS alone was independently associated with mortality (HR 4.43, 95% CI 1.85-10.57). None of the sarcopenia components conferred a higher risk of mobility disability. The EWGSOP2 algorithm leads to a reduction in the estimated prevalence of sarcopenia defined as combination of LMM/LMS. The finding that, independent of the adopted criteria, people with LMS and normal mass have a higher mortality risk compared to robust individuals, confirms that evaluation of muscle strength has a central role for prognosis evaluation.

The Tribulations of Trials: Lessons Learnt Recruiting 777 Older Adults Into REtirement in ACTion (REACT), a Trial of a Community, Group-Based Active Aging Intervention Targeting Mobility Disability.

BackgroundChallenges of recruitment to randomized controlled trials (RCTs) and successful strategies to overcome them should be clearly reported to improve recruitment into future trials. REtirement in ACTion (REACT) is a United Kingdom-based multicenter RCT recruiting older adults at high risk of mobility disability to a 12-month group-based exercise and behavior maintenance program or to a minimal Healthy Aging control intervention.MethodsThe recruitment target was 768 adults, aged 65 years and older scoring 4–9 on the Short Physical Performance Battery (SPPB). Recruitment methods include the following: (a) invitations mailed by general practitioners (GPs); (b) invitations distributed via third-sector organizations; and (c) public relations (PR) campaign. Yields, efficiency, and costs were calculated.ResultsThe study recruited 777 (33.9% men) community-dwelling, older adults (mean age 77.55 years (SD 6.79), mean SPPB score 7.37 (SD 1.56)), 95.11% white (n = 739) and broadly representative of UK quintiles of deprivation. Over a 20-month recruitment period, 25,559 invitations were issued. Eighty-eight percent of the participants were recruited via GP invitations, 5.4% via the PR campaign, 3% via word-of-mouth, and 2.5% via third-sector organizations. Mean recruitment cost per participant was £78.47, with an extra £26.54 per recruit paid to GPs to cover research costs.ConclusionsREACT successfully recruited to target. Response rates were lower than initially predicted and recruitment timescales required adjustment. Written invitations from GPs were the most efficient method for recruiting older adults at risk of mobility disability. Targeted efforts could achieve more ethnically diverse cohorts. All trials should be required to provide recruitment data to enable evidence-based planning of future trials.

COGNITIVE DECLINE ENHANCES VULNERABILITY TO ENVIRONMENTAL DETERMINANTS OF MOBILITY

Neighborhood and residential characteristics can potentially influence mobility of older adults but associations may differ based on cognitive function. We tested whether neighborhood and residential characteristics derived from audits of Google Streetview images were related to 4-year incident mobility disability and whether these associations differed by cognitive trajectories (maintainer vs decliner over 14 years). In 260 participants from the Health ABC (mean age=81.8 years, 57% female, 39% black), Cox proportional hazard models tested associations stratified by cognitive trajectory, adjusted for demographics. Mixed compared to residential land use was associated with greater risk of mobility disability among cognitive decliners (HR=1.27, 95% CI: 1.05-1.54) but not cognitive maintainers (HR=1.07, 95% CI: 0.90-1.28). Presence of slopes near the home and having a ramp at the home entrance were associated with lower mobility disability risk, again in decliners only. Lower cognitive function may increase vulnerability to poorer neighborhood and residential characteristics for mobility outcomes.

Association of Fish Oil and Physical Activity on Mobility Disability in Older Adults.

This study aimed to examine whether long-term fish oil (FO) supplementation is associated with a lower risk of mobility disability and enhances benefits of physical activity (PA). A total of 1635 sedentary adults age 70 to 89 yr from the Lifestyle Interventions and Independence for Elders single-blinded randomized, multicenter clinical trial, which compared a structured PA program to a health education program. Primary outcome was incident major mobility disability (MMD), defined by loss of ability to walk 400 m, measured every 6 months for an average of 2.6 yr. Secondary outcomes included persistent mobility disability, Short Physical Performance Battery, 400-m walk speed, and grip strength. A third of participants reported using FO at baseline (456 (28%); mean age, 78.5 yr; 70.5% women). MMD was experienced by 131 participants (28.7%) in the FO group and 405 (34.4%) participants in the nonuser group. After adjusting for confounders, FO supplementation was associated with a lower risk (HR, 0.78; 95% confidence interval (CI), 0.64-0.96) of incident MMD. However, there was no interaction (P = 0.19) between FO supplementation and PA intervention for MMD. For the secondary outcome of persistent mobility disability, the intervention association differed by supplementation (P = 0.002) with PA intervention associations of (HR, 1.36; 95% CI, 0.83-2.23) for users and (HR, 0.61; 95% CI, 0.46-0.81) for nonusers. Changes in physical performance outcomes were not modified by baseline FO supplementation or combination with PA. FO supplementation was associated with a lower risk of MMD in low to moderate functioning older adults. However, supplementation did not enhance the benefit of PA on risk of mobility disability. These results are hypothesis generating and need to be confirmed in randomized trials.

Associations of Usual Pace and Complex Task Gait Speeds With Incident Mobility Disability.

To assess whether gait speed under complex conditions predicts long-term risk for mobility disability as well as or better than usual-pace gait speed. Longitudinal cohort study. Subsample of Health Aging and Body Composition study with follow-up from 2002 to 2003 to 2010 to 2011, including 337 community-dwelling adults (mean age = 78.5 years, 50.7% female, 26.1% black). Associations of gait speed measured under usual-pace, fast-pace, dual-task, and narrow-path conditions with mobility disability, defined by any self-reported difficulty walking ¼ mile assessed annually, were tested by Cox proportional hazard models adjusted for demographic and health characteristics. Models were fitted for each walking condition, and R2 statistics were used to compare predictive value across models. Models were repeated for persistent mobility disability, defined as at least two consecutive years of mobility disability. Mobility disability occurred in 204 (60.5%) participants over the 8-year follow-up. There was a lower hazard of developing mobility disability with faster gait speed under all conditions. Hazard ratios, confidence intervals, and R2 of gait speed predicting mobility disability were similar across all four walking conditions (R2 range = 0.22-0.27), but were strongest for dual-task gait speed (hazard ratio [95% confidence interval], R2 of fully adjusted models = 0.81 [0.75-0.88], 0.27). Results were comparable for persistent mobility disability (R2 range = 0.26-0.28). Slower gait speed under both usual-pace and complex conditions may be a clinical indicator of future risk of mobility disability. These results support the call for increased use of gait speed measures in routine geriatric care. J Am Geriatr Soc 67:2072-2076, 2019.

Vitamin K Status and Mobility Limitation and Disability in Older Adults: The Health, Aging, and Body Composition Study.

Vitamin K has been implicated in chronic diseases associated with increased risk for mobility disability, such as osteoarthritis and cardiovascular disease. However, the association between vitamin K status and mobility disability is unknown. Therefore, we examined the association between vitamin K status and incident mobility disability in the Health, Aging, and Body Composition Study. Plasma phylloquinone (vitamin K1) was categorized as <0.5, 0.5-<1.0 and ≥1.0 nmol/L (n = 1,323, 48% male). Plasma ucMGP, which increases when vitamin K status is low, was measured in 716 participants and categorized into tertiles. Mobility limitation and disability, defined as two consecutive semiannual reports of having any or a lot of difficulty walking a one-fourth mile or climbing 10 steps without resting, were assessed over a median 6-10 years of follow-up. Multivariate Cox proportional hazard models were used to evaluate the association between vitamin K status and incident mobility limitation and disability. Participants with plasma phylloquinone less than 0.5 nmol/L were more likely to develop mobility limitation and disability compared to those with at least 1.0 nmol/L (adjusted HR (95% CI) mobility limitation: 1.27 (1.05-1.53); disability: 1.34 (1.01-1.76)). After further adjustment for knee pain, the associations were partially attenuated (HR (95% CI) mobility limitation: 1.20 (0.99-1.45); disability: 1.26 (0.96-1.67)). Plasma ucMGP was not associated with incident mobility limitation, but was nonlinearly associated with incident mobility disability (HR (95% CI), compared to tertile 1: tertile 2 = 1.64 (1.19-2.27), tertile 3 = 1.17 (0.83-1.66), fully adjusted). Our results suggest vitamin K may be involved in the disablement process in older age. Future studies are needed to confirm our findings and clarify the underlying mechanism.

Establishing the Link Between Lean Mass and Grip Strength Cut Points With Mobility Disability and Other Health Outcomes: Proceedings of the Sarcopenia Definition and Outcomes Consortium Conference.

Lack of consensus on how to diagnose sarcopenia has limited the ability to diagnose this condition and hindered drug development. The Sarcopenia Definitions and Outcomes Consortium (SDOC) was formed to develop evidence-based diagnostic cut points for lean mass and/or muscle strength that identify people at increased risk of mobility disability. We describe here the proceedings of a meeting of SDOC and other experts to discuss strategic considerations in the development of evidence-based sarcopenia definition. Presentations and panel discussions reviewed the usefulness of sarcopenia as a biomarker, the analytical approach used by SDOC to establish cut points, and preliminary findings, and provided strategic direction to develop an evidence-based definition of sarcopenia. The SDOC assembled data from eight epidemiological cohorts consisting of 18,831 participants, clinical populations from 10 randomized trials and observational studies, and 2 nationally representative cohorts. In preliminary assessments, grip strength or grip strength divided by body mass index was identified as discriminators of risk for mobility disability (walking speed <0.8 m/s), whereas dual-energy X-ray absorptiometry-derived lean mass measures were not good discriminators of mobility disability. Candidate definitions based on grip strength variables were associated with increased risk of mortality, falls, mobility disability, and instrumental activities of daily living disability. The prevalence of low grip strength increased with age. The attendees recommended the establishment of an International Expert Panel to review a series of position statements on sarcopenia definition that are informed by the findings of the SDOC analyses and synthesis of literature. International consensus on an evidence-based definition of sarcopenia is needed. Grip strength-absolute or adjusted for body mass index-is an important discriminator of mobility disability and other endpoints. Additional research is needed to develop a predictive risk model that takes into account sarcopenia components as well as age, sex, race, and comorbidities.

The Experience and Meaning of Physical Activity in Assisted Living Facility Residents.

Assisted living (AL) residents engage in very low levels of physical activity (PA), placing them at increased risk for mobility disability and frailty. But many residents in AL may not perceive the need to increase their PA. This study explored the experience, meaning, and perceptions of PA in 20 older adults in AL. The factors associated with PA were also examined. Qualitative data were collected using semistructured interviews and analyzed using phenomenological methodology. Six themes were identified: PA was experienced as planned exercise, activities of daily living, and social activities based on a schedule or routine; PA meant independence and confidence in the future; residents perceived themselves as being physically active; social comparisons influenced perception of PA; personal health influenced PA; motivations and preferences influenced PA. The findings highlight the importance of residents' personal perceptions of PA and effects of the social milieu in the congregate setting on PA.

Physical activity patterns and multimorbidity burden of older adults with different levels of functional status: NHANES 2003–2006

BackgroundPhysical function and physical activity decrease with age, but differences in physical activity patterns within different physical functioning groups are unknown. ObjectivesTo describe physical activity patterns and multimorbidity burden by physical function group and age. MethodsActigraph accelerometer-derived physical activity patterns were compared by physical function (high functioning, activity limitations, activity of daily living disabled) determined by questionnaire and age among 2174 older adults (mean age = 70.9, sd = 0.2 years) from the cross-sectional 2003–2006 National Health and Nutrition Examination Survey. Associations between physical function, physical activity, and multimorbidity were examined. ResultsReduced physical function and increased age were associated with lower physical activity, increased sedentary time and a compressed activity profile. During the most active hour of the day (11:00 a.m.), the oldest, lowest physical functioning group was 82% less active than the youngest, highest physical functioning group. High functioning had over 30% more total activity counts, over 56% more time in moderate-to-vigorous activity, about 8% less time sedentary and took approximately one more sedentary break/hour than lower physical functioning groups. Gender differences in physical activity variables were prevalent for high functioning, but limited within reduced physical functioning groups. Physical function, age, total activity counts/day, and breaks in sedentary time/day were independently associated with multimorbidity (p < 0.005). ConclusionsReduced physical function and increased age are associated with physical activity levels, and all three are associated with multimorbidity. Understanding physical activity differences by physical function is important for designing interventions for older individuals at increased risk for mobility disability.

A LINC00341-mediated regulatory pathway supports chondrocyte survival and may prevent osteoarthritis progression.

Osteoarthritis (OA) is the most common degenerative joint diseaseandresults from progressive loss and destruction of articular cartilage and the underlying bone. The disease affects millions of people worldwide with an associated risk of mobility disability. However, the molecular basis underlying OA initiation and progression is not well understood and, currently, there is no effective intervention available to decelerate disease progression or restore degraded cartilage. We have found that lncRNA long intergenic nonprotein coding RNA 341 (LINC00341) is aberrantly downregulated in OA patient tissues and cultured OA chondrocytes. This is likely responsible for the increased apoptosis of chondrocytes and pathological destruction of cartilage. Further investigation has revealed that LINC00341 interacts with miR-141 to suppress its functional binding to the 3'-untranslated region of YY1-associated factor 2 (YAF2) messenger RNA. Aberrant downregulation of LINC00341 thus may ultimately lead to inhibition of the YAF2 protein, which has been implicated to be an antiapoptotic factor. Our study has revealed a new noncoding RNA-mediated regulatory network that highly likely protects chondrocytes by preventing apoptosis under normal conditions. The results will help further explore the molecular details pertaining to the progression of OA and stimulate efforts to develop effective therapies.

Physical Activity and Performance Impact Long-term Quality of Life in Older Adults at Risk for Major Mobility Disability

Older adults are a rapidly growing segment of the U.S. Mobility problems that lead to further disability can be addressed through physical activity interventions. Quality of life outcome results are reported from a large trial of physical activity for sedentary older adults at risk for mobility disability. Data were from the Lifestyle Interventions and Independence for Elders study. This multisite RCT compared physical activity to health education among 1,635 randomly assigned sedentary older adults at risk for mobility disability in 2010-2011. Measures included demographics; comorbidity; a timed 400-meter walk; the Short Physical Performance Battery; and the Quality of Well-Being Scale (0-1.0 scale). Baseline and long-term follow-up (2.6 years) health-related quality of life data were collected as a secondary outcome. Multivariate linear regression modeling was used to examine covariates of health-related quality of life over time in 2017. The sample had an overall mean Quality of Well-Being score of 0.613. Both groups declined in quality of life over time, but assignment to the physical activity intervention resulted in a slower decline in health-related quality of life scores (p=0.03). Intervention attendance was associated with higher health-related quality of life for both groups. Baseline characteristics including younger age, fewer comorbid conditions, non-white ethnicity, and faster 400-meter walk times were also associated with higher health-related quality of life over time. Declining mobility measured by physical performance is associated with lower quality of life in sedentary older adults. Physical activity interventions can slow the decline in quality of life, and targeting specific subgroups may enhance the effects of such interventions.

To study the effect of Yogabasti in Sandhigata vata

Osteoarthritis is the clinical and pathological outcome of a range of disorders that result in structural and functional failure of synovial joints. Osteoarthritis is the most prevalent form of arthritis, with an associated risk of mobility disability (defined as needing help walking or climbing stairs) for those with affected knees being greater than that due to any other medical condition in people aged. The societal burden (both in terms of personal suffering and use of health resources) is expected to increase with the increasing prevalence of obesity and the aging of the community.&#x0D; Osteoarthritis is a multifactorial process in which mechanical factors have a central role and is characterized by changes in the structure and function of the whole joint. There is no cure, and current therapeutic strategies are primarily aimed at reducing pain and improving joint function. &#x0D; Whereas in Ayurveda, Sandhigata Vata is the commonest form of articular disorder. It is a type of Vatavyadhi which mainly occurs in Vriddhavastha due to Dhatukshaya. That having similar symptoms as that of Osteoarthritis. In Ayurvedic classics, our Acharya has given so many special therapeutic procedures for specific disease along with thousands of no. of medicines. Due to easy availability and less cost of the drugs and the adverse effect of Basti. Basti is Ardha chikitsa according to Ayurveda. The incidence of osteoarthritis in India is as high as 12%. It is estimated that approximately four out of 100 people are affected by it. Osteoarthritis is the most common articular disorder begins asymptomatically in the 2nd &amp; 3rd decades and is extremely common by age 70.

Translating the Lifestyle Interventions and Independence for Elders Clinical Trial to Older Adults in a Real-World Community-Based Setting.

The Lifestyle Interventions and Independence for Elders (LIFE) clinical trial demonstrated that a structured program of physical activity (PA) reduced mobility-disability in older adults by up to 28%. It remains unknown whether the benefits of LIFE PA can be translated to older adults at risk for mobility-disability in real-world community-based settings. To address this knowledge gap, we conducted the ENhancing independence using Group-based community interventions for healthy AGing in Elders (ENGAGE) pilot study and examined the safety, feasibility, and preliminary effectiveness of translating LIFE PA to a community-based senior center. Forty older adults with severe lower extremity functional limitations (age: 76.9 ± 7.3 years; body mass index: 32.7 ± 8 kg/m2; 85% female; short physical performance battery score: 6.3 ± 2.2) were randomized to 24 weeks of PA or a health education control intervention. Community-based PA was safe (serious adverse events: PA vs health education, 0:2; nonserious adverse events: PA vs health education, 3:1) and participants successfully adhered to the PA intervention (65.2%). Compared to health education, PA participants who attended ≥25% of scheduled visits had meaningful and sustained short physical performance battery improvements at follow-up (between group short physical performance battery score differences: ~0.7 units). ENGAGE has demonstrated the preliminary safety, feasibility, and effectiveness of LIFE PA in a real-world community-based setting. Larger-scale translational studies are needed to further disseminate the benefits of LIFE PA to vulnerable older adults in a variety of community-based settings.

Abstract P263: Acid-Base Status as a Modifier of Loss of Lean Mass During Intentional Weight Loss in Older Adults

Weight loss interventions present a unique challenge in older adults: relative loss of lean mass during weight loss, if superimposed on age-related sarcopenia may increase the risk for mobility disability. Relative loss of lean mass (25-30%) during weight loss depends on the severity/duration of caloric restriction, initial body mass, and concomitant exercise training. We hypothesized that subclinical imbalances of acid-base status (reflected in lower serum bicarbonate) may also affect relative loss of lean mass during weight loss. The rationale: even subtle imbalances of acid-base status (e.g. bicarbonate &lt;23 mmol) impact clinical outcomes in older adults such as gait speed or incidence of functional limitation, while bicarbonate supplementation reduces urinary nitrogen wasting and may improve physical function. However, data on acid-base balance and serum bicarbonate during moderate caloric restriction are lacking. We, therefore, analyzed 2 randomized, controlled weight loss trials (including moderate caloric restriction and exercise): The Diet, Exercise, and Metabolism for Older Women [DEMO; (58±5.2 y)] and Cooperative Lifestyle Program; [CLIP; (67±4.7 y)]. Serum bicarbonate was assessed as total CO 2 (in mmol) and whole body lean mass measured by dual-energy X-ray absorptiometry. The analysis showed that 48% of participants had bicarbonate &lt;23. DEMO participants with lower serum bicarbonate at baseline lost more lean mass during the intervention (unadjusted β(SE)=0.32(0.16); p=0.04; n=92). Adjustments for age, BMI, eGFR, % weight loss, baseline, intervention group, had little effect, but adjusting for protein intake during weight loss attenuated the association (β(SE)=0.17(0.15); p=0.28.). Similarly, a change in serum bicarbonate during the trial was associated with % lean mass change, but attenuated after controlling for protein intake. This is not unexpected: protein is acid-producing and one of two major determinants of net dietary acid load; higher dietary acid load correlates with lower serum bicarbonate, in older adults. Results from the CLIP trial were remarkably similar, and consistently, baseline serum bicarbonate level was marginally predictive of baseline daily protein intake, with highest baseline serum bicarbonate having the lowest protein intake [bicarbonate: &gt;24 (n=58); &gt;21-24 (n=121); &lt;21 (N=93); protein in g/kg body weight 0.7(0.4); 0.9(0.4); 0.8(0.4) respectively, p=0.057). In conclusion, our analysis suggests that higher serum bicarbonate before and during weight loss may ameliorate loss of lean mass, however, to obtain definitive answer such analysis needs to be conducted under conditions of controlled or randomized protein intake. Importantly, our findings suggest that oral bicarbonate supplementation, a simple and relatively safe intervention, may ameliorate loss of lean mass during weight loss interventions in older adults.

Three-Year Changes in Physical Activity and Subsequent Loss of Ability to Walk 400 m in Older Adults: The InCHIANTI Study.

We examined the associations of maintaining or increasing physical activity (PA) for a 3-yr follow-up with subsequent incident inability to complete the 400-m walk test (i.e., mobility disability) for 6 yrs of follow-up in older adults. This study included 421 participants 65 yrs and older. The 400-m walk test was assessed at baseline and at 3-, 6-, and 9-yr follow-up. Physical activity was self-reported through a 6-point rating scale at baseline and 3-yr follow-up. Three-year cumulative PA (i.e., average at baseline and at 3-yr follow-up) and its changes (i.e., from baseline to 3-yr follow-up) were linked to subsequent incidence of mobility disability for 6 yrs of follow-up (i.e., from 3- to 9-yr follow-up), after adjustment for potential covariates. After the 3-yr period, incidence of mobility disability for the subsequent 6 yrs of follow-up occurred in 129 participants. The odds ratio (95% confidence interval) of incident mobility disability associated with 1-category increase in cumulative PA was 0.63 (0.41-0.97, P = 0.036). The odds ratio (95% confidence interval) of incident mobility disability associated with 1-category increase in changes in PA was 0.56 (0.38-0.84, P = 0.005). Hence, maintaining or increasing PA levels is associated with a reduced risk of mobility disability among older adults.

Resting State Default Mode Network Connectivity, Dual Task Performance, Gait Speed, and Postural Sway in Older Adults with Mild Cognitive Impairment.

Aging is associated with an increased risk of falling. In particular, older adults with mild cognitive impairment (MCI) are more vulnerable to falling compared with their healthy counterparts. Major contributors to this increased falls risk include a decline in dual task performance, gait speed, and postural sway. Recent evidence highlights the potential influence of the default mode network (DMN), the frontoparietal network (FPN), and the supplementary motor area (SMA) on dual task performance, gait speed, and postural sway. The DMN is active during rest and deactivates during task-oriented processes, to maintain attention and stay on task. The FPN and SMA are involved in top-down attentional control, motor planning, and motor execution. The DMN shows less deactivation during task in older adults with MCI. This lack of deactivation is theorized to increase competition for resources between the DMN and task-related brain regions (e.g., the FPN and SMA), increasing distraction from the task and reducing task performance. However, no study has yet investigated the relationship between the between-network connectivity of the DMN with these regions and dual task walking, gait speed or postural sway. We hypothesized that greater functional connectivity both within the DMN and between DMN–FPN and DMN–SMA, will be associated with poorer performance during dual task walking, slower gait speed, and greater postural sway in older adults with MCI. Forty older adults with MCI were measured on a dual task-walking paradigm, gait speed over a 4-m walk, and postural sway using a sway-meter. Greater within-DMN connectivity was significantly correlated with poorer dual task performance. Furthermore, greater inter-network connectivity between the DMN and SMA was significantly correlated with slower gait speed and greater postural sway on the eyes open floor sway task. Thus, greater resting state DMN functional connectivity may be an underlying neural mechanism for reduced dual task ability, slower gait speed, and greater postural sway, resulting in the increased risk of mobility disability and falling in older adults with MCI.

Device-Measured Physical Activity As a Predictor of Disability in Mobility-Limited Older Adults.

To examine associations between objectively measured physical activity (PA) and incidence of major mobility disability (MMD) and persistent MMD (PMMD) in older adults in the Lifestyle Interventions and Independence for Elders (LIFE) Study. Prospective cohort of individuals aged 65 and older undergoing structured PA intervention or health education. The LIFE Study was a multicenter (eight sites) randomized controlled trial designed to compare the efficacy of a long-term structured PA intervention with that of a health education (HE) program in reducing the incidence of MMD in mobility-limited older adults. LIFE Study participants (n = 1,590) had a mean age±standard deviation of 78.9 ± 5.2, low levels of PA, and measured mobility-relevant functional impairment at baseline. Activity data were collected using hip-worn 7-day accelerometers at baseline and 6, 12, and 24 months after randomization to test for associations with incident MMD and PMMD (≥2 consecutive instances of MMD). At baseline, every 30 minutes spent being sedentary (<100 accelerometry counts per minute) was associated with higher rate of subsequent MMD (10%) and PMMD (11%) events. Every 500 steps taken was associated with lower rate of MMD (15%) and PMMD (18%). Similar associations were observed when fitting accelerometry-based PA as a time-dependent variable. Accelerometry-based PA levels were strongly associated with MMD and PMMD events in older adults with limited mobility. These results support the importance of daily PA and lower amounts of sedentary time levels in this population and suggest that accelerometry may be a useful tool for assessing risk of mobility disability.

Effects of a Long-Term Physical Activity Program on Activity Patterns in Mobility Impaired Older Adults

PURPOSE: To examine the effect of a long-term structured physical activity intervention on accelerometer-derived metrics of activity composition changes in older adults at high risk for mobility disability. METHODS: Participants were randomized to either a physical activity (PA) or health education (HE) program. The PA intervention included a walking regimen with strength, flexibility, and balance training. The HE program featured health-related discussions and a brief upper body stretching routine. Participants (n = 1,341) wore a hip-worn accelerometer for ≥10 h/day for ≥3 days at baseline and again at 6, 12 and 24 months post-randomization. Total physical activity (TPA)—defined as movements registering 100+ counts/min—was segmented into the following intensities: low light (LLPA; 100-759 counts/min), high light (HLPA; 760-1,040 counts/min), low moderate (LMPA; 1,041-2,019 counts/min), and high moderate and greater (HMPA; 2,020+ counts/min) physical activity. Patterns of activity were characterized as bouts (defined as the consecutive minutes within an intensity). RESULTS: Both groups decreased TPA (-10.5±1.0 minutes/day annually), but the PA intervention attenuated this effect (PA vs HE: +6.4±2.1 minutes/day, p<0.001). This attenuation shifted TPA composition by increasing daily time in HLPA (1+ bouts: 0.8±0.3; 5+ bouts: 0.2±0.04; 10+ bouts: 0.1±0.02 minutes), LMPA (1+ bouts: 2.7±0.4; 2+ bouts: 2.4±0.3; 5+ bouts: 2.0±0.2; 10+ bouts: 1.1±0.1 minutes), and HMPA (1+ bouts: 2.8±0.4; 2+ bouts: 2.5±0.3; 5+ bouts: 2.1±0.3; 10+ bouts: 1.7±0.2 minutes). All findings were statistically significant at p<0.01. DISCUSSION: The PA intervention increased physical activity by shifting the composition of activity toward higher intensity activity in longer duration bouts. However, a long-term structured physical activity intervention did not completely eliminate overall declines in total daily activity experienced by mobility impaired older adults.