Integrated Social- and Neurocognitive Model of Physical Activity Behavior in Older Adults with Metabolic Disease.

BACKGROUND: Despite the proven benefits of physical activity to treat and prevent metabolic diseases, such as diabetes (T2D) and metabolic syndrome (MetS), most individuals with metabolic disease do not meet physical activity (PA) recommendations. PA is a complex behavior requiring substantial motivational and cognitive resources. The purpose of this study was to examine social cognitive and neuropsychological determinants of PA behavior in older adults with T2D and MetS. The hypothesized model theorized that baseline self-regulatory strategy use and cognitive function would indirectly influence PA through self-efficacy. METHODS: Older adults with T2D or MetS (M age = 61.8 ± 6.4) completed either an 8-week physical activity intervention (n = 58) or an online metabolic health education course (n = 58) and a follow-up at 6 months. Measures included cognitive function, self-efficacy, self-regulatory strategy use, and PA. RESULTS: The data partially supported the hypothesized model (χ2 = 158.535(131), p > .05, comparative fit index = .96, root mean square error of approximation = .04, standardized root mean square residual = .06) with self-regulatory strategy use directly predicting self-efficacy (ß = .33, p < .05), which in turn predicted PA (ß = .21, p < .05). Performance on various cognitive function tasks predicted PA directly and indirectly via self-efficacy. Baseline physical activity (ß = .62, p < .01) and intervention group assignment via self-efficacy (ß = -.20, p < .05) predicted follow-up PA. The model accounted for 54.4 % of the variance in PA at month 6. CONCLUSIONS: Findings partially support the hypothesized model and indicate that select cognitive functions (i.e., working memory, inhibition, attention, and task-switching) predicted PA behavior 6 months later. Future research warrants the development of interventions targeting cognitive function, self-regulatory skill development, and self-efficacy enhancement. TRIAL REGISTRATION NUMBER: The trial was registered with the clinical trial number NCT01790724.

Fitness, but not physical activity, is related to functional integrity of brain networks associated with aging.

Greater physical activity and cardiorespiratory fitness are associated with reduced age-related cognitive decline and lower risk for dementia. However, significant gaps remain in the understanding of how physical activity and fitness protect the brain from adverse effects of brain aging. The primary goal of the current study was to empirically evaluate the independent relationships between physical activity and fitness with functional brain health among healthy older adults, as measured by the functional connectivity of cognitively and clinically relevant resting state networks. To build context for fitness and physical activity associations in older adults, we first demonstrate that young adults have greater within-network functional connectivity across a broad range of cortical association networks. Based on these results and previous research, we predicted that individual differences in fitness and physical activity would be most strongly associated with functional integrity of the networks most sensitive to aging. Consistent with this prediction, and extending on previous research, we showed that cardiorespiratory fitness has a positive relationship with functional connectivity of several cortical networks associated with age-related decline, and effects were strongest in the default mode network (DMN). Furthermore, our results suggest that the positive association of fitness with brain function can occur independent of habitual physical activity. Overall, our findings provide further support that cardiorespiratory fitness is an important factor in moderating the adverse effects of aging on cognitively and clinically relevant functional brain networks.

Differential exercise effects on quality of life and health-related quality of life in older adults: a randomized controlled trial.

PURPOSE: Maintaining quality of life (QOL) and physical and mental health status are important outcomes throughout the aging process. Although cross-sectional studies suggest a relationship between global QOL and physical activity, it is unclear whether such a relationship exists as a function of exercise training. METHODS: We examined the effects of two exercise intervention arms on health-related quality of life (HRQOL) and global QOL. Low-active, older adults (n = 179) were randomly assigned to either a 12-month aerobic walking group or a strengthening and flexibility group. HRQOL and QOL were measured at baseline, 6, and 12 months. RESULTS: There was a significant group by time effect on QOL [F(2,176) = 3.11, p = 0.047, η (2) = 0.03]. There was also a significant overall group by time effect for HRQOL [F(4,174) = 2.46, p = 0.047, η (2) = 0.05], which was explained by the significant group by time interaction for mental health status (p = 0.041, η (2) = 0.02) favoring the walking condition. Further analyses using latent class analysis revealed three classes of individuals with differential patterns of change in QOL and HRQOL across time. These classes reflected no change, declines, and improvements in these constructs across time. CONCLUSIONS: Walking appears to enhance the mental aspect of HRQOL and global QOL when compared to a non-aerobic intervention. Additionally, the patterns of change in QOL and HRQOL were not linear over time. Our findings are in contrast to previous reports that these outcomes change a little or not at all in randomized trials.

Impact of a brief intervention on self-regulation, self-efficacy and physical activity in older adults with type 2 diabetes.

Despite evidence of the benefits of physical activity, most individuals with type 2 diabetes do not meet physical activity recommendations. The purpose of this study was to test the efficacy of a brief intervention targeting self-efficacy and self-regulation to increase physical activity in older adults with type 2 diabetes. Older adults (Mage = 61.8 ± 6.4) with type 2 diabetes or metabolic syndrome were randomized into a titrated physical activity intervention (n = 58) or an online health education course (n = 58). The intervention included walking exercise and theory-based group workshops. Self-efficacy, self-regulation and physical activity were assessed at baseline, post-intervention, and a follow-up. Results indicated a group by time effect for self-regulation [F(2,88) = 14.021, p < .001, η (2) = .24] and self-efficacy [F(12,77) = 2.322, p < .05, η (2) = .266] with increases in the intervention group. The intervention resulted in short-term increases in physical activity (d = .76, p < .01), which were partially maintained at the 6-month follow-up (d = .35, p < .01). The intervention increased short-term physical activity but was not successful at maintaining increases in physical activity. Similar intervention effects were observed in self-efficacy and self-regulation. Future research warrants adjusting intervention strategies to increase long-term change.

Physical activity levels and patterns in older adults: the influence of a DVD-based exercise program.

The use of multimedia to influence health behaviors offers unique advantages over more traditional center-based programs, however, little is known about the effectiveness of such approaches in improving physical activity levels over time. The purpose of this study was to examine the efficacy of a progressive and age-appropriate, DVD-delivered exercise program in promoting physical activity levels among older adult cohorts. Community dwelling older adults (N = 307, Mean age = 71 years) were randomized to one of two groups: a 6-month home-based DVD-delivered exercise (i.e., FlexToBa™) intervention group or a healthy aging DVD control group. Physical activity was assessed objectively using a standard 7-day accelerometer wear period and subjectively using the Godin Leisure Time Exercise Questionnaire, at baseline and follow-up. Analysis of covariances indicated a statistically significant treatment effect for subjectively [F(1,250) = 8.42, P = .004, η(2) = .03] and objectively [F(1,240) = 3.77, P = .05, η(2) = .02] measured physical activity. The older cohort (>70) in the FlexToBa condition further had significantly larger improvements in physical activity levels compared to their younger counterparts. From a public health perspective, media-delivered interventions such as the FlexToBa program might prove to be cost-effective, have a broader reach and at the same time be effective in improving physical activity levels in older adults.

Influence of allowable interruption period on estimates of accelerometer wear time and sedentary time in older adults.

The criteria one uses to reduce accelerometer data can profoundly influence the interpretation of research outcomes. The purpose of this study was to examine the influence of 3 different interruption periods (i.e., 20, 30, and 60 min) on the amount of data retained for analyses and estimates of sedentary time among older adults. Older adults (N = 311, M age = 71.1) wore an accelerometer for 7 d and reported wear time on an accelerometer log. Accelerometer data were downloaded and scored using 20-, 30-, and 60-min interruption periods. Estimates of wear time, derived using each interruption period, were compared with self-reported wear time, and descriptive statistics were used to compare estimates of sedentary time. Results showed a longer interruption period (i.e., 60 min) yields the largest sample size and the closest approximation of self-reported wear time. A short interruption period (i.e., 20 min) is likely to underestimate sedentary time among older adults.

Neurobiological markers of exercise-related brain plasticity in older adults.

The current study examined how a randomized one-year aerobic exercise program for healthy older adults would affect serum levels of brain-derived neurotrophic factor (BDNF), insulin-like growth factor type 1 (IGF-1), and vascular endothelial growth factor (VEGF) - putative markers of exercise-induced benefits on brain function. The study also examined whether (a) change in the concentration of these growth factors was associated with alterations in functional connectivity following exercise, and (b) the extent to which pre-intervention growth factor levels were associated with training-related changes in functional connectivity. In 65 participants (mean age=66.4), we found that although there were no group-level changes in growth factors as a function of the intervention, increased temporal lobe connectivity between the bilateral parahippocampus and the bilateral middle temporal gyrus was associated with increased BDNF, IGF-1, and VEGF for an aerobic walking group but not for a non-aerobic control group, and greater pre-intervention VEGF was associated with greater training-related increases in this functional connection. Results are consistent with animal models of exercise and the brain, but are the first to show in humans that exercise-induced increases in temporal lobe functional connectivity are associated with changes in growth factors and may be augmented by greater baseline VEGF.

A profile for predicting attrition from exercise in older adults.

The purpose of this study was to determine a profile for predicting attrition among older adults involved in a 12-month exercise program. The parent study was a single-blinded randomized controlled trial. The study took place between 2006 and 2009 within a university setting. Older adults (N = 179) completed baseline assessments of functional performance and psychosocial measures. Participants who were randomized, elected to receive treatment, and did not complete the exercise program were considered "dropouts" (n = 35). Those who completed the program (n = 144) were classified as "completers." A latent profile analysis revealed two distinct patterns of memory complaints, self-efficacy to overcome barriers to exercise, balance performance, and stair performance. Dropouts were nearly twice as likely to be members of the profile that exhibited a higher degree of memory complaints, lower self-efficacy for overcoming exercise barriers, poorer single leg balance, and longer times to walk down stairs. The results provide an initial validation of a profile for discriminating between "dropouts" and "completers," one that may have considerable utility for screening older adults prior to study entry.

Measuring enjoyment of physical activity in older adults: invariance of the physical activity enjoyment scale (paces) across groups and time.

The purpose of this study was to validate the Physical Activity Enjoyment Scale (PACES) in a sample of older adults. Participants within two different exercise groups were assessed at two time points, 6 months apart. Group and longitudinal invariance was established for a novel, 8-item version of the PACES. The shortened, psychometrically sound measure provides researchers and practitioners an expedited and reliable instrument for assessing the enjoyment of physical activity.

Longitudinal invariance and construct validity of the abbreviated late-life function and disability instrument in healthy older adults.

OBJECTIVE: To cross-validate the psychometric properties of the abbreviated Late-Life Function and Disability Instrument (LL-FDI), a measure of perceived functional limitations and disability. DESIGN: Baseline and 12-month follow-up assessments conducted across the course of a 12-month exercise program. SETTING: University research community. PARTICIPANTS: Older healthy adults (N=179; mean ± SD age, 66.43±5.67y) at baseline; 145 were retained at follow-up. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: LL-FDI and functional performance measures. RESULTS: Factor analyses confirmed the factor structure of the abbreviated LL-FDI, and all subscales met minimal criteria for temporal invariance. Significant correlations also were found between functional limitations subscales and an array of physical function performance measures, supporting the scale's construct validity. CONCLUSIONS: The abbreviated LL-FDI with some modifications appears to be temporally invariant in community-dwelling older adults. Additionally, moderate relationships between functional limitations and functional performance provide further support for these being conceptually distinct constructs.

Trajectories of change in self-esteem in older adults: exercise intervention effects.

This 12-month, 2 arm, single blind randomized controlled exercise trial examined relationships among changes in multidimensional self-esteem as a function of intervention mode (i.e., walking vs. flexibility-toning-balance). Data were collected on three equidistant occasions (baseline, 6 and 12 months). One-hundred seventy-nine older adults (M(age) = 66.38) began the study and 145 completed assessments at all time points. Participants completed measures of physical and global self-esteem as well as demographic information. There were no significant group differences at baseline on these demographic indicators or esteem variables. Data were analyzed using linear and parallel process growth modeling procedures. Results supported the position that across both groups, domain-level (i.e., physical self-worth) was dependent upon sub-domain-level (i.e., perceived attractiveness, strength, and condition) esteem change. Furthermore, greater improvements were observed in the flexibility-toning-balance group, in terms of perceived strength and attractiveness esteem, compared to the walking group. Our findings support theoretically-based predictions and extend the literature showing unique psychological responses conditional on specific types of physical activities.

Functional implications of muscle co-contraction during gait in advanced age.

Older adults often exhibit high levels of lower extremity muscle co-contraction, which may be the cause or effect of age-related impairments in gait and associated falls. Normal gait requires intact executive function and thus can be slowed by challenging executive resources available to the neuromuscular system through the performance of a dual task. We therefore investigated associations between lower limb co-contraction and gait characteristics under normal and dual task conditions in healthy older adults (85.4±5.9years). We hypothesized that greater co-contraction is associated with slower gait speed during dual task conditions that stress executive and attentional abilities. Co-contraction was quantified during different phases of the gait cycle using surface electromyography (EMG) signals obtained from the anterior tibialis and lateral gastrocnemius while walking at preferred speed during normal and dual task conditions. Variables included the time difference to complete the Trail Making Test A and B (ΔTMT) and gait measures during normal or dual task walking. Higher co-contraction levels during the swing phase of both normal and dual task walking were associated with longer ΔTMT (normal: R2=0.25, p=0.02; dual task: R2=0.27, p=0.01). Co-contraction was associated with gait measures during dual task walking only; greater co-contraction levels during stride and stance were associated with slower gait speed (stride: R2=0.38, p=0.04; stance: R2=0.38, p=0.04), and greater co-contraction during stride was associated with longer stride time (R2=0.16, p=0.03). Our results suggest that relatively high lower limb co-contraction may explain some of the mobility impairments associated with the conduct of executive tasks in older adults.

Maintenance Effects of a DVD-Delivered Exercise Intervention on Physical Function in Older Adults.

BACKGROUND: Exercise training has been demonstrated to enhance physical function and to have a protective effect against functional limitations and disability in older adults. PURPOSE: The objective of this study was to determine whether the effects of a home-based, DVD-delivered exercise intervention on functional performance and limitations were maintained 6-month postintervention termination. METHODS: Follow-up assessments of functional performance and limitations were conducted in a sample of community-dwelling older adults (N = 237) who participated in a 6-month randomized controlled exercise trial. Participants were initially randomized to a DVD-delivered exercise intervention or an attentional control condition. The Short Physical Performance Battery, measures of flexibility and strength, and functional limitations were assessed immediately before and after the intervention and then again 6 months later. Analyses of covariance were conducted to examine changes in physical function between the two conditions at the end of the intervention to 6-month follow-up. RESULTS: There were statistically significant adjusted group differences in the Short Physical Performance Battery (η(2) = 0.03, p = .01), upper-body strength (η(2) = 0.03, p = .005), and lower-body flexibility (η(2) = 0.02, p = .05), indicating that gains brought about by the intervention were maintained 6 months later. CONCLUSIONS: A DVD-delivered exercise program specifically designed to target elements of functional fitness in older adults can produce clinically meaningful gains in physical function that are maintained beyond intervention cessation.

Meeting physical activity guidelines in rural breast cancer survivors.

OBJECTIVES: To examine the contribution of social cognitive constructs to meeting physical activity (PA) recommendations in rural breast cancer survivors (BCS). METHODS: Rural BCS (N = 483) completed a mail-based survey. PA, fatigue, barriers and exercise self-efficacy, environment, social support, and perceived barriers to PA were assessed. PA was dichotomized into either meeting guidelines (150+minutes/week) or not. RESULTS: Our model fit the data well with less fatigue, greater efficacy, and lower barriers being associated with PA (χ²=804.532(418), p < .001, CFI=.948, RMSEA=.044, SRMR=.046). CONCLUSIONS: Fatigue, self-efficacy, and perceived barriers are key targets for future interventions designed to increase PA in rural BCS. Enhancing self-efficacy and overcoming barriers will require strategies unique and relevant to BCS living in rural settings.

Differential trajectories of well-being in older adult women: the role of optimism.

BACKGROUND: Well-being is important to healthy aging. The present study examined the trajectories and determinants of well-being in older women (n = 248) over a 39-month period. METHODS: Participants completed measures of optimism, pessimism, functional limitations, physical activity, and self-efficacy. Well-being, operationalised as life satisfaction, was assessed at baseline, 12, 24, and 39 months. Latent growth and class analyses examined trajectories of well-being and antecedents of change. RESULTS: The overall model testing a linear growth pattern fit the data well [χ(2) (df = 5) = 7.77, p = .17, CFI = .98, RMSEA = .05], revealing an overall significant, but modest decline in well-being. Three latent classes were further revealed; one class (n = 34, 13.3%) began with moderate levels of well-being (Mi = 25.4, p < .001), which decreased across time (Ms = -3.12, p < .001). A second class (n = 54, 21.8%) began with lower well-being (Mi = 17.1, p < .001) that remained low (Ms = .702, p = .378). The third class (n = 161, 64.9%) started with high levels of well-being (Mi = 28.4, p < .001) which were maintained (Ms = -.027, p = .841). Higher optimism and lower pessimism differentiated between declining well-being and maintaining well-being across time. CONCLUSIONS: Optimism and pessimism appear to differentiate patterns of well-being in community-dwelling older women. Promoting optimism-inducing strategies may be useful for maintaining well-being in older adulthood.

Executive function processes predict mobility outcomes in older adults.

OBJECTIVES: To examine the relationship between performance on executive function measures and subsequent mobility outcomes in community-dwelling older adults. DESIGN: Randomized controlled clinical trial. SETTING: Champaign-Urbana, Illinois. PARTICIPANTS: Community-dwelling older adults (N = 179; mean age 66.4). INTERVENTION: A 12-month exercise trial with two arms: an aerobic exercise group and a stretching and strengthening group. MEASUREMENTS: Established cognitive tests of executive function (flanker task, task switching, and a dual-task paradigm) and the Wisconsin card sort test. Mobility was assessed using the timed 8-foot up and go test and times to climb up and down a flight of stairs. METHODS: Participants completed the cognitive tests at baseline and the mobility measures at baseline and after 12 months of the intervention. Multiple regression analyses were conducted to determine whether baseline executive function predicted postintervention functional performance after controlling for age, sex, education, cardiorespiratory fitness, and baseline mobility levels. RESULTS: Selective baseline executive function measurements, particularly performance on the flanker task (ß = 0.15-0.17) and the Wisconsin card sort test (ß = 0.11-0.16) consistently predicted mobility outcomes at 12 months. The estimates were in the expected direction, such that better baseline performance on the executive function measures predicted better performance on the timed mobility tests independent of intervention. CONCLUSION: Executive functions of inhibitory control, mental set shifting, and attentional flexibility were predictive of functional mobility. Given the literature associating mobility limitations with disability, morbidity, and mortality, these results are important for understanding the antecedents to poor mobility function that well-designed interventions to improve cognitive performance can attenuate.

Physical activity and cardiorespiratory fitness are beneficial for white matter in low-fit older adults.

Physical activity (PA) and cardiorespiratory fitness (CRF) are associated with better cognitive function in late life, but the neural correlates for these relationships are unclear. To study these correlates, we examined the association of both PA and CRF with measures of white matter (WM) integrity in 88 healthy low-fit adults (age 60-78). Using accelerometry, we objectively measured sedentary behavior, light PA, and moderate to vigorous PA (MV-PA) over a week. We showed that greater MV-PA was related to lower volume of WM lesions. The association between PA and WM microstructural integrity (measured with diffusion tensor imaging) was region-specific: light PA was related to temporal WM, while sedentary behavior was associated with lower integrity in the parahippocampal WM. Our findings highlight that engaging in PA of various intensity in parallel with avoiding sedentariness are important in maintaining WM health in older age, supporting public health recommendations that emphasize the importance of active lifestyle.

Effects of a DVD-delivered exercise intervention on physical function in older adults.

BACKGROUND: Given the rapidly increasing demographic of older adults, it is vital to implement effective behavioral strategies to improve physical function to maintain activities of daily living. However, changing physical activity in older adults remains extremely difficult. The current trial tested the efficacy of a novel, 6-month, home-based, DVD-delivered exercise program focusing on flexibility, balance, and toning on the physical function of older adults. METHODS: Older adults (N = 307) were recruited from 83 towns and cities throughout central Illinois. The trial consisted of 4 waves of recruitment and randomization from May 2010 through January 2012. Inclusion criteria included being inactive, at least 65 years of age, English speaking, providing physician's consent, and willingness to be randomized. Eligible participants were randomly assigned to 1 of 2 treatment conditions: the exercise intervention or a healthy aging, attentional control. Functional assessments were completed at baseline and following the 6-month DVD intervention. Measures included the Short Physical Performance Battery, assessments of flexibility and strength, and self-reported functional limitations. RESULTS: Participants in the DVD intervention condition demonstrated significant improvements in the Short Physical Performance Battery (p = .005), lower extremity flexibility (p = .04), and upper body strength (p = .003). There were no effects of the intervention on self-reported functional limitations. CONCLUSIONS: The exercise intervention produced a clinically significant improvement in the Short Physical Performance Battery and improvements in flexibility and strength, demonstrating the effectiveness of a low-cost DVD exercise program in improving physical function in older adults.

Thinness expectations and weight cycling in a sample of middle-aged adults.

BACKGROUND: The False Hope Syndrome suggests that unrealistic expectations of dieting and weight loss are key constructs in the prediction of behavioral failure and may exacerbate weight cycling. The objective of this study was to determine cross-sectional associations among dieting and thinness expectations and weight cycling history within the framework of the False Hope Syndrome. METHODS: Participants were middle-aged (45±12 years) women (n=116) and men (n=98) recruited via worksite intranet distributions. Information on dieting and thinness expectations, weight loss attempts, and weight cycling history was gathered using standard questionnaires. RESULTS: More women than men reported currently dieting (43% vs. 26%; p<0.01). Moderate [OR=2.54; 95%CI: 1.01-6.45] and higher [OR=2.70; 95%CI: 1.07-6.80] levels of the thinness expectation score were significantly associated with the greater odds of weight cycling, independent of age, sex, BMI, and weight loss attempts. CONCLUSIONS: These data are the first to extend the pervasive and potent influence of thinness expectancy to middle-aged persons and in particular, to men.

Caudate Nucleus Volume Mediates the Link between Cardiorespiratory Fitness and Cognitive Flexibility in Older Adults.

The basal ganglia play a central role in regulating the response selection abilities that are critical for mental flexibility. In neocortical areas, higher cardiorespiratory fitness levels are associated with increased gray matter volume, and these volumetric differences mediate enhanced cognitive performance in a variety of tasks. Here we examine whether cardiorespiratory fitness correlates with the volume of the subcortical nuclei that make up the basal ganglia and whether this relationship predicts cognitive flexibility in older adults. Structural MRI was used to determine the volume of the basal ganglia nuclei in a group of older, neurologically healthy individuals (mean age 66 years, N = 179). Measures of cardiorespiratory fitness (VO(2max)), cognitive flexibility (task switching), and attentional control (flanker task) were also collected. Higher fitness levels were correlated with higher accuracy rates in the Task Switching paradigm. In addition, the volume of the caudate nucleus, putamen, and globus pallidus positively correlated with Task Switching accuracy. Nested regression modeling revealed that caudate nucleus volume was a significant mediator of the relationship between cardiorespiratory fitness, and task switching performance. These findings indicate that higher cardiorespiratory fitness predicts better cognitive flexibility in older adults through greater grey matter volume in the dorsal striatum.