Mobility Limitation In Older Adults Research Articles

Foot Pain and Mobility Limitations in Older Adults: The Framingham Foot Study

Foot pain is very common in the general population and has been shown to have a detrimental impact on health-related quality of life. This is of particular concern in older people as it may affect activities of daily living and exacerbate problems with balance and gait. The objective of this study is to evaluate the independent relationships between foot pain and mobility limitation in a population of community-dwelling older adults. Population-based cross-sectional study. Participants (n = 1,544) from the Framingham Foot Study (2002-2008) were assessed for physical performance. Foot pain was documented using the question "On most days, do you have pain, aching, or stiffness in either foot?" Mobility limitation was assessed using the Short Physical Performance Battery, dichotomized using 1-9 as an indicator of mobility limitation and 10-12 as no mobility limitation. Foot pain was reported by 19% of men and 25% of women. After adjusting for age, obesity, smoking status, and depression, foot pain was significantly associated with mobility limitation in both men (odds ratio = 2.00, 95% confidence interval 1.14 - 3.50; p = .016) and women (odds ratio = 1.59, 95% confidence interval 1.03 - 2.46; p = .037). In our study of older adults from the Framingham Foot Study, foot pain was associated with an increased odds of having mobility limitation in both men and women. Clinicians should consider assessment of foot pain in general examinations of older adults who are at risk of mobility limitation.

A Comparison of Straight- and Curved-Path Walking Tests Among Mobility-Limited Older Adults

Habitual gait speed (HGS) and the figure-of-8 walking test (F8WT) are measures of walking ability that have been associated with mobility outcomes and disability among older adults. Our objective was to contrast the physiologic, health, and behavioral attributes underlying performance of these two walking tests among older adults with mobility limitations. HGS and F8WT were the primary outcomes. HGS was measured as time needed to walk a 4-m straight course at usual pace from standstill position. F8WT was measured as time to walk in a figure-of-8 pattern at self-selected usual pace from standstill position. Separate multivariable linear regression models were constructed that predicted walking performance. Independent variables included physiologic, cognitive-behavioral health attributes, and demographic information. Of 430 participants, 414 completed both walking tests. Participants were 67.7% female, had a mean age of 76.5 ± 7.0 years and a mean of 4.1 ± 2.0 chronic conditions. Mean HGS was 0.94 ± 0.23 m/s and mean F8WT was 8.80 ± 2.90 seconds. Within separate multivariable linear regression models (HGS: R (2) = .46, p model < .001; F8WT: R (2) = .47, p model < .001), attributes statistically significant within both models included: trunk extension endurance, ankle range of motion, leg press velocity at peak power, executive function, and sensory loss. Cognitive and physiologic attributes uniquely associated with F8WT were cognitive processing speed and self-efficacy, and reaction time and heel-to-floor time. Pain and peak leg press strength were associated with only HGS. Both HGS and F8WT are useful tests of walking performance. Factors uniquely associated with F8WT suggest that it may be well suited for use among older adult patients with balance problems or at risk for falls.

Efficacy of Whey Protein Supplementation on Resistance Exercise–Induced Changes in Lean Mass, Muscle Strength, and Physical Function in Mobility-Limited Older Adults

Whey protein supplementation may augment resistance exercise-induced increases in muscle strength and mass. Further studies are required to determine whether this effect extends to mobility-limited older adults. The objectives of the study were to compare the effects of whey protein concentrate (WPC) supplementation to an isocaloric control on changes in whole-body lean mass, mid-thigh muscle cross-sectional area, muscle strength, and stair-climbing performance in older mobility-limited adults in response to 6 months of resistance training (RT). Eighty mobility-limited adults aged 70-85 years were randomized to receive WPC (40g/day) or an isocaloric control for 6 months. All participants also completed a progressive high-intensity RT intervention. Sample sizes were calculated based on the primary outcome of change in whole-body lean mass to give 80% power for a 0.05-level, two-sided test. Lean mass increased 1.3% and 0.6% in the WPC and control groups, respectively. Muscle cross-sectional area was increased 4.6% and 2.9% in the WPC and control groups, respectively, and muscle strength increased 16%-50% in WPC and control groups. Stair-climbing performance also improved in both groups. However, there were no statistically significant differences in the change in any of these variables between groups. These data suggest that WPC supplementation at this dose does not offer additional benefit to the effects of RT in mobility-limited older adults.

Association Between Chair Stand Strategy and Mobility Limitations in Older Adults With Symptomatic Knee Osteoarthritis

ObjectiveTo determine which lower limb strength and joint kinetic and kinematic parameters distinguish sit-to-stand (STS) performance of older adults with symptomatic knee osteoarthritis (OA) with higher and lower chair stand time. DesignCross-sectional. SettingMotion analysis laboratory. ParticipantsIndividuals (N=49; 26 men, 23 women) aged 50 to 79 years (mean ± SD age, 64.7±8.1y) with radiographic knee OA and daily symptoms, stratified by chair stand times. InterventionsNot applicable. Main Outcome MeasuresLower limb strength and STS strategy. ResultsThe chair stand times (mean ± SD) in the high-, moderate-, and low-functioning groups in men were 6.5±0.7, 8.6±0.7, and 11.5±1.3 seconds, respectively, and in women were 7.6±1.2, 10.0±0.5, and 12.8±1.8 seconds, respectively. Chair stand time (P=.0391) and all measures of lower limb strength (all P<.0001) differed by sex. In men, no strength measure differed between groups, whereas in women hip abductor strength on the more affected side differed between groups. In men, sagittal hip range of motion (ROM) (P=.0122) differed between groups, and there was a trend toward a difference in sagittal knee power (P=.0501) during STS, while in women only sagittal knee ROM (P=.0392) differed between groups. ConclusionsHigher- and lower-functioning adults with symptomatic knee OA appear to use different strategies when standing from a chair. Higher-functioning men flexed more at the hip and produced greater knee power than lower-functioning men. Higher-functioning women used less knee flexion than lower-functioning women. Since STS is an important mobility task, these parameters may serve as foci for rehabilitation aimed at reducing mobility limitations.

Influences on Neighborhood Walking in Older Adults

The purpose of this cross-sectional survey study was to examine the influence of self-efficacy, outcome expectations, and environment on neighborhood walking in older adults with (n = 163, mean age = 78.7, SD = 7.96 years) and without (n = 163, mean age = 73.6, SD = 7.93 years) mobility limitations, controlling for demographic characteristics. Multiple regression revealed that in mobility-limited older adults, demographic characteristics, self-efficacy, and outcome expectations explained 17.4% of variance in neighborhood walking, while environment (neighborhood destinations and design) explained 9.4%. Destinations, self-efficacy, sex, and outcome expectations influenced walking. In those without mobility limitations, demographic characteristics, self-efficacy, and outcome expectations explained 15.6% of the variance, while environment explained 5.6%. Self-efficacy, sex, and design influenced walking. Neighborhood walking interventions for older adults should include self-efficacy strategies tailored to mobility status and neighborhood characteristics.

The specific contributions of force and velocity to muscle power in older adults

The purpose of this study is to examine the relative importance of the force-based and velocity-based measures of muscle performance to explain inter-individual differences in power production capability and functional task performance. Participants included seventy-nine men and women: middle-aged healthy adults (MH: 40–55years), older healthy adults (OH: 70–85years), and older adults with mobility limitations (OML: 70–85years). Muscle power at 180°/s, isometric maximal torque, and maximal contraction velocity at 40% 1RM were measured during unilateral leg extension. The Short Physical Performance Battery (SPPB) was used to differentiate between healthy and mobility limited older adults. Functional task performance was assessed using multiple chair rise and stair climb tests. Leg extensor force (torque), but not maximal contraction velocity, was significantly associated with muscle power in MH. Both torque and velocity were significantly associated with muscle power in OH. Maximal velocity, but not torque, was associated with power in OML. Maximal velocity demonstrated an association with multiple chair rise time and stair climb time in OML, but not MH or OH. It is concluded that movement velocity is an increasingly important determinant of maximal power output with advancing age. Furthermore, movement velocity is also a critical component of functional task performance with aging and may contribute to functional deficits. These findings help to explain why the rate-dependent variable power has emerged as a critical component of both assessment and rehabilitation of muscular performance and physical function in older adults.

Validity of an Exercise Test Based on Habitual Gait Speed in Mobility-Limited Older Adults

Li X, Forman DE, Kiely DK, LaRose S, Hirschberg R, Frontera WR, Bean JF. Validity of an exercise test based on habitual gait speed in mobility-limited older adults. ObjectiveTo evaluate whether a customized exercise tolerance testing (ETT) protocol based on an individual's habitual gait speed (HGS) on level ground would be a valid mode of exercise testing older adults. Although ETT provides a useful means to risk-stratify adults, age-related declines in gait speed paradoxically limit the utility of standard ETT protocols for evaluating older adults. A customized ETT protocol may be a useful alternative to these standard methods, and this study hypothesized that this alternative approach would be valid. DesignWe performed a cross-sectional analysis of baseline data from a randomized controlled trial of older adults with observed mobility problems. Screening was performed using a treadmill-based ETT protocol customized for each individual's HGS. We determined the content validity by assessing the results of the ETTs, and we evaluated the construct validity of treadmill time in relation to the Physical Activity Scale for the Elderly (PASE) and the Late Life Function and Disability Instrument (LLFDI). SettingOutpatient rehabilitation center. ParticipantsCommunity-dwelling, mobility-limited older adults (N=141). InterventionsNot applicable. Main Outcome MeasuresCardiac instability, ETT duration, peak heart rate, peak systolic blood pressure, PASE, and LLFDI. ResultsAcute cardiac instability was identified in 4 of the participants who underwent ETT. The remaining participants (n=137, 68% female; mean age, 75.3y) were included in the subsequent analyses. Mean exercise duration was 9.39 minutes, with no significant differences in durations being observed after evaluating among tertiles by HGS status. Mean peak heart rate and mean peak systolic blood pressure were 126.6 beats/min and 175.0mmHg, respectively. Within separate multivariate models, ETT duration in each of the 3 gait speed groups was significantly associated (P<.05) with PASE and LLFDI. ConclusionsMobility-limited older adults can complete this customized ETT protocol, allowing for the identification of acute cardiac instability and the achievement of optimal exercise parameters.

Muscle power failure in mobility-limited older adults: preserved single fiber function despite lower whole muscle size, quality and rate of neuromuscular activation

This study investigated the physiological and gender determinants of the age-related loss of muscle power in 31 healthy middle-aged adults (aged 40-55 years), 28 healthy older adults (70-85 years) and 34 mobility-limited older adults (70-85 years). We hypothesized that leg extensor muscle power would be significantly lower in mobility-limited elders relative to both healthy groups and sought to characterize the physiological mechanisms associated with the reduction of muscle power with aging. Computed tomography was utilized to assess mid-thigh body composition and calculate specific muscle power and strength. Surface electromyography was used to assess rate of neuromuscular activation and muscle biopsies were taken to evaluate single muscle fiber contractile properties. Peak muscle power, strength, muscle cross-sectional area, specific muscle power and rate of neuromuscular activation were significantly lower among mobility-limited elders compared to both healthy groups (P ≤ 0.05). Mobility-limited older participants had greater deposits of intermuscular adipose tissue (P < 0.001). Single fiber contractile properties of type I and type IIA muscle fibers were preserved in mobility-limited elders relative to both healthy groups. Male gender was associated with greater decrements in peak and specific muscle power among mobility-limited participants. Impairments in the rate of neuromuscular activation and concomitant reductions in muscle quality are important physiological mechanisms contributing to muscle power deficits and mobility limitations. The dissociation between age-related changes at the whole muscle and single fiber level suggest that, even among older adults with overt mobility problems, contractile properties of surviving muscle fibers are preserved in an attempt to maintain overall muscle function.

Age-Related Eye Disease and Mobility Limitations in Older Adults

To examine the extent of mobility limitations in patients with age-related macular degeneration (AMD), glaucoma, or Fuchs' corneal dystrophy compared with that in a control group of older adults with good vision. Two hundred seventy-two patients (68 with AMD, 49 with Fuchs' dystrophy, 82 with glaucoma, and 73 controls) from the ophthalmology clinics of Maisonneuve-Rosemont Hospital (Montreal, Canada) participated in a cross-sectional study from September 2009 until February 2011. Control patients who had normal visual acuity and visual fields were recruited from the same clinics. Questionnaire (life space, falls, and driving) and performance-based (one-legged balance test, Timed Up and Go [TUG] test) mobility data were collected; visual acuity, contrast sensitivity, and visual field were measured; and the medical record was reviewed. The three eye diseases were associated with different patterns of mobility limitations. Patients with glaucoma had the most types of mobility limitations, as they had reduced life-space scores, had worse TUG scores, were less likely to drive, and were more likely to have poor balance than the control group (P < 0.05). Compared with the controls, patients with AMD and Fuchs' corneal dystrophy had reduced life-space scores and were less likely to drive (P < 0.05). The results suggest that eye diseases, especially glaucoma, restrain the mobility of older people in many different ways. It is important to further explore the impact of eye disease on mobility in this population, to develop interventions that could help affected older adults maintain their independence.

Gait pattern alterations in older adults associated with type 2 diabetes in the absence of peripheral neuropathy—Results from the Baltimore Longitudinal Study of Aging

Diabetes may impact gait mechanics before onset of frank neuropathies and other associated threats to mobility. This study aims to characterize gait pattern alterations of type 2 diabetic adults without peripheral neuropathy during walking at maximum speed (fast-walking) as well as at self-selected speed (usual-walking). One-hundred and eighty-six participants aged 60–87 from the Baltimore Longitudinal Study of Aging (BLSA) able to walk unassisted and without peripheral neuropathy were classified as non-diabetic ( N = 160) or having type 2 diabetes ( N = 26). Gait parameters from the fast-walking and usual-walking tests were compared between participants with and without type 2 diabetes. Participants with diabetes had a shorter stride length for fast-walking ( p = 0.033) and a longer percentage of the gait cycle with the knee in 1st flexion for both fast- and usual-walking ( p = 0.033, and 0.040, respectively) than non-diabetic participants. Participants with diabetes exhibited a smaller hip range of motion in the sagittal plane during usual-walking compared to non-diabetics ( p = 0.049). During fast-walking, participants with diabetes used lower ankle generative mechanical work expenditure (MWE) and higher knee absorptive MWE compared to non-diabetic persons ( p = 0.021, and 0.018, respectively). These findings suggest that individuals with type 2 diabetes without overt peripheral neuropathy exhibit altered and less efficient gait patterns than non-diabetic persons. These alterations are more apparent during walking at a maximum speed indicating that maximum gait testing may be useful for identifying early threats to mobility limitations in older adults with type 2 diabetes.

Increased Trunk Extension Endurance Is Associated With Meaningful Improvement in Balance Among Older Adults With Mobility Problems

Suri P, Kiely DK, Leveille SG, Frontera WR, Bean JF. Increased trunk extension endurance is associated with meaningful improvement in balance among older adults with mobility problems. Objective To determine whether trunk extension endurance changes with training are associated with clinically meaningful improvements in balance among mobility-limited older adults. Design Longitudinal data from a randomized controlled trial. Setting Outpatient rehabilitation research center. Participants Community-dwelling older adults (N=64; mean age, 75.9y) with mobility limitations as defined by a score of 4 to 10 on the Short Physical Performance Battery. Interventions Sixteen weeks of progressive resistance training. Main Outcome Measures Outcomes were the Berg Balance Scale (BBS) and the Unipedal Stance Time (UST). Predictors included leg strength, leg power, trunk extension endurance, and the product of heart rate and blood pressure (RPP) at the final stage of an exercise tolerance test. We performed an analysis of data from participants who completed 16 weeks of training by using binary outcomes defined by a clinically meaningful change (CMC) from baseline to completion of the intervention (BBS=4 units; UST=5s). The association of predictor variables with balance outcomes was examined separately and together in multivariate adjusted logistic regression models. Results Trunk extension endurance in seconds (1.04 [1.00–1.09]) was independently associated with CMC on the BBS. Trunk extension endurance (1.02 [1.00–1.03]) was independently associated with CMC on the UST. Other physical attributes were not associated with meaningful change in balance. Conclusions Improvements in trunk extension endurance were independently associated with CMCs in balance in older adults. Leg strength, leg power, and RPP were not associated with CMC in balance. Poor trunk extension endurance may be a rehabilitative impairment worthy of further study as a modifiable factor linked to balance among older adults.

Are Changes in Leg Power Responsible for Clinically Meaningful Improvements in Mobility in Older Adults?

From among physiological attributes commonly targeted in rehabilitation, to identify those in which changes led to clinically meaningful differences (CMDs) in mobility outcomes. Secondary analysis of data collected for a randomized controlled trial of exercise using binary outcomes defined by recording a large CMD (Short Physical Performance Battery (SPPB)=1 unit; gait speed (GS)=0.1 m/s). Iterative models were performed to evaluate possible confounding between physiological variables and relevant covariates. Outpatient rehabilitation centers. Community-dwelling mobility-limited older adults (n=116) participating in a 16-week randomized controlled trial of two modes of exercise. Physiological measures included leg power, leg strength, balance as measured according to the Performance-Oriented Mobility Assessment (POMA), and rate pressure product at the maximal stage of an exercise tolerance test. Outcomes included GS and SPPB. Leg power and leg strength were measured using computerized pneumatic strength training equipment and recorded in Watts and Newtons, respectively. Participants were 68% female, had a mean age of 75.2, a mean of 5.5 chronic conditions, and a baseline mean SPPB score of 8.7. After controlling for age, site, group assignment, and baseline outcome values, leg power was the only attribute in which changes were significantly associated with a large CMD in SPPB (odds ratio (OR)=1.48, 95% confidence interval (CI)=1.09-2.02) and GS (OR=1.31, 95% CI=1.01-1.70). Improvements in leg power, independent of strength, appear to make an important contribution to clinically meaningful improvements in SPPB and GS.

Estimating Transition Probabilities in Mobility and Total Costs for Medicare Beneficiaries

Hoffman JM, Ciol MA, Huynh M, Chan L. Estimating transition probabilities in mobility and total costs for Medicare beneficiaries. Objective To examine how persons move back and forth along levels of mobility disability. Design Self-reported mobility limitations were used to create categories of annual transition states. The total cost to Medicare associated with each year was calculated for each participant. In addition, we examined cost relative to transition state, adjusting for demographic and other health status variables. Setting National survey. Participants Participants in the longitudinal Medicare Current Beneficiary Survey from 1992 to 2005. Interventions Not applicable. Main Outcome Measures Annual self-reported mobility limitations and total Medi costs. Results Most participants remained without mobility limitations or improved over time. Reported average costs were 10 times higher for those who transitioned to severe limitations, unable to walk, or death compared with persons who reported no mobility limitation. Estimated costs were highest for those transitioning to increased states of disability and to death. Conclusions Mobility limitations in older adults are dynamic, and improvement (as measured by annual transitions) occurred for a large number of Medicare beneficiaries. High total annual costs were observed in groups that transitioned to worsening mobility states, suggesting a link between mobility limitation transitions and cost. Prevention and treatment of mobility limitation may be an important factor to consider in health care reform.

Impaired Voluntary Neuromuscular Activation Limits Muscle Power in Mobility-Limited Older Adults

Age-related alterations of neuromuscular activation may contribute to deficits in muscle power and mobility function. This study assesses whether impaired activation of the agonist quadriceps and antagonist hamstrings, including amplitude- and velocity-dependent characteristics of activation, may explain differences in leg extension torque and power between healthy middle-aged, healthy older, and mobility-limited older adults. Torque, power, and electromyography were recorded during maximal voluntary leg extension trials across a range of velocities on an isokinetic dynamometer. Neuromuscular activation was similar between middle-aged and older healthy groups, with differences in torque and power explained predominantly by muscle size. However, the older mobility-limited group demonstrated marked impairment of torque, power, and agonist muscle activation, with the greatest deficits occurring at the fastest movement velocities. Agonist muscle activation was found to be strongly associated with torque output. Similar neuromuscular activation between the middle-aged and older healthy groups indicates that impaired voluntary activation is not an obligatory consequence of aging. However, the finding that the mobility-limited group exhibited impaired activation of the agonist quadriceps and concomitant deficits in torque and power output suggests that neuromuscular activation deficits may contribute to compromised mobility function in older adults.

Trunk Muscle Attributes Are Associated With Balance and Mobility in Older Adults: A Pilot Study

To determine whether trunk muscle attributes are associated with balance and mobility performance among mobility-limited older adults. Cross-sectional analysis of data from a randomized clinical trial. Outpatient rehabilitation research center. Community-dwelling older adults (N = 70; mean age 75.9 years) with mobility limitations as defined by the Short Physical Performance Battery (SPPB). Independent variables included physiologic measures of trunk extension strength, trunk flexion strength, trunk extension endurance, trunk extension endurance, and leg press strength. All measures were well tolerated by the study subjects without the occurrence of any associated injuries or adverse events. The association of each physiologic measure with each outcome was examined by the use of separate multivariate models to calculate the partial variance (R(2)) of each trunk and extremity measure. Balance measured by the Berg Balance Scale and Unipedal Stance Test and mobility performance as measured by the SPPB. Trunk extension endurance (partial R(2) = .14, P = .02), and leg press strength (partial R(2) = .14, P = .003) accounted for the greatest amount of the variance in SPPB performance. Trunk extension endurance (partial R(2) = .17, P = .007), accounted for the greatest amount of the variance in BBS performance. Trunk extension strength (R(2) = .09, P = .03), accounted for the greatest amount of the variance in UST performance. The variance explained by trunk extension endurance equaled or exceeded the variance explained by limb strength across all three performance outcomes. Trunk endurance and strength can be safely measured in mobility-limited older adults and are associated with both balance and mobility performance. Trunk endurance and trunk strength are physiologic attributes worthy of targeting in the rehabilitative care of mobility-limited older adults.

The Prevalence and Severity of Physical Mobility Limitations in Older Adults with Intellectual Disabilities

Background The population of older adults with intellectual disabilities is growing, creating new challenges for individuals, families and service providers. Although there has been increased research into the ageing process for adults with intellectual disabilities, there is little focused research investigating physical mobility.Materials and Methods A proxy‐response telephone survey was conducted to establish the prevalence and severity of mobility limitations among adults with intellectual disabilities, aged 45 years and over, using validated instruments to quantify mobility in a representative population‐based sample.Results Surveys were completed for 128 people. Mobility limitations were common, but the prevalence varied depending on the definition of mobility limitation. The prevalence of limitations was greater among females than males, but no clear age trend was seen.Conclusions The common nature of mobility limitations among the growing population of older adults with intellectual disabilities has implications for service providers and policy‐makers.

Increased Velocity Exercise Specific to Task Training Versus the National Institute on Aging's Strength Training Program: Changes in Limb Power and Mobility

This study was designed to evaluate the benefits of InVEST (Increased Velocity Specific to Task) training on limb power and mobility among mobility-limited older adults. We conducted a single blinded, randomized controlled trial among 138 mobility-limited community-dwelling older adults, evaluating two 16-week supervised exercise programs. The intervention group participated in InVEST training, and the control group participated in the National Institute on Aging's (NIA) strength training program. Primary outcomes were changes in limb power per kilogram and mobility performance as measured by the Short Physical Performance Battery (SPPB). After 16 weeks, InVEST produced significantly greater improvements in limb power than NIA (p=.02). There was no significant difference in strength improvements. Both groups had significant changes in SPPB of greater than 1 unit. Self-reported function was also significantly improved in both groups. Differences between groups were not statistically different. In a post hoc analysis when participants were categorized by the manifestation of baseline leg velocity impairments (N=68), InVEST training produced effect size differences in SPPB that were clinically meaningful (SPPB Group x Time difference 0.73 units, p=.05). Among mobility-limited older adults, both NIA and InVEST produce robust changes in observed physical performance and self-reported function. These improvements were not meaningfully different by statistical or clinical criteria. Compared with NIA, InVEST training produced greater improvements in limb power and equivalent improvements in strength. Observed differences between NIA and InVEST based upon baseline leg impairment status are informative for futures studies.

Activity Energy Expenditure and Mobility Limitation in Older Adults: Differential Associations by Sex

In this study, the authors aimed to determine whether higher activity energy expenditure, assessed by using doubly labeled water, was associated with a reduced decline in mobility limitation among 248 older community-dwelling US adults aged 70-82 years enrolled in 1998-1999. Activity energy expenditure was calculated as total energy expenditure (assessed over 2 weeks by using doubly labeled water) minus resting metabolic rate (measured with indirect calorimetry), with adjustment for the thermic effect of food. Across sex-specific tertiles of activity energy expenditure, men in the lowest activity group experienced twice the rate of mobility limitation as men in the highest activity group (41% (n = 18) vs. 18% (n = 8)). Conversely, women in the lowest and highest activity groups exhibited similarly high rates of mobility limitation (40% (n = 16) vs. 38% (n = 15)). After adjustment for potential confounders, men with higher activity energy expenditure levels continued to show reduced risk of mobility limitation (per standard deviation (284 kcal/day): hazard ratio = 0.61, 95% confidence interval: 0.41, 0.92). Women showed no association (per standard deviation (226 kcal/day): hazard ratio = 1.34, 95% confidence interval: 0.98, 1.85). Greater energy expenditure from any and all physical activity was significantly associated with reduced risk of developing mobility limitation among men, but not among women.

Overweight and Obesity Over the Adult Life Course and Incident Mobility Limitation in Older Adults: The Health, Aging and Body Composition Study

Obesity in middle and old age predicts mobility limitation; however, the cumulative effect of overweight and/or obesity over the adult life course is unknown. The association between overweight and/or obesity in young, middle, and late adulthood and its cumulative effect on incident mobility limitation was examined among community-dwelling US adults aged 70-79 years at baseline (1997-1998) in the Health, Aging and Body Composition Study (n = 2,845). Body mass index was calculated by using recalled weight at ages 25 and 50 years and measured weight at ages 70-79 years. Mobility limitation (difficulty walking 1/4 mile (0.4 km) or climbing 10 steps) was assessed semiannually over 7 years of follow-up and was reported by 43.0% of men and 53.7% of women. Men and women who were overweight or obese at all 3 time points had an increased risk of mobility limitation (hazard ratio = 1.61, 95% confidence interval: 1.25, 2.06 and hazard ratio = 2.85, 95% confidence interval: 2.15, 3.78, respectively) compared with those who were normal weight throughout. Furthermore, there was a significant graded response (P < 0.0001) on risk of mobility limitation for the cumulative effect of obesity in men and overweight and/or obesity in women. Onset of overweight and obesity in earlier life contributes to an increased risk of mobility limitation in old age.

Which Impairments Are Most Associated With High Mobility Performance in Older Adults? Implications for a Rehabilitation Prescription

Bean JF, Kiely DK, LaRose S, Leveille SG. Which impairments are most associated with high mobility performance in older adults? Implications for a rehabilitation prescription. Objective To test which rehabilitative impairments are associated with higher mobility performance among community-dwelling, mobility-limited older adults. Design Cross-sectional analysis of baseline data from participants within a randomized controlled trial. Setting Outpatient rehabilitation research center. Participants Community-dwelling older adults (N=138; mean age, 75.4y) with mobility limitations as defined by the Short Physical Performance Battery (SPPB). Interventions Not applicable. Main Outcome Measures Balance measured via the Berg Balance Scale, leg strength, leg velocity, submaximal aerobic capacity, body mass index (BMI), and mobility performance as measured by the SPPB. Results Each of the 5 physiologic attributes (unipedal balance, leg strength, leg velocity, submaximal aerobic capacity, BMI) was categorized into tertiles by using lower values as reference for impairment status. Within an adjusted model, measures associated with higher SPPB performance (>9) included a BBS score greater than or equal to 54 (odds ratio [OR]=4.54; 95% confidence interval [CI], 1.11–18.60), leg strength greater than or equal to 21.5N/kg (OR=30.35; 95% CI, 5.48–168.09), leg velocity .0101 to .0129m·s −1·kg −1 (OR=5.31; 95% CI, 1.25–22.57), and leg velocity greater than or equal to .0130m·s −1·kg −1 (OR=22.86; 95% CI, 3.88–134.75). Conclusions Our investigation highlights the importance of rehabilitative impairments in leg strength, leg velocity, and balance as being associated with mobility status as measured by the SPPB. In our sample of participants within an exercise trial, submaximal aerobic capacity and BMI status were not associated with mobility performance. These findings suggest that the augmentation of not only leg strength and balance but also leg velocity may be important in the rehabilitative care of mobility-limited older adults.