Exercise training increases size of hippocampus and improves memory.

The hippocampus shrinks in late adulthood, leading to impaired memory and increased risk for dementia. Hippocampal and medial temporal lobe volumes are larger in higher-fit adults, and physical activity training increases hippocampal perfusion, but the extent to which aerobic exercise training can modify hippocampal volume in late adulthood remains unknown. Here we show, in a randomized controlled trial with 120 older adults, that aerobic exercise training increases the size of the anterior hippocampus, leading to improvements in spatial memory. Exercise training increased hippocampal volume by 2%, effectively reversing age-related loss in volume by 1 to 2 y. We also demonstrate that increased hippocampal volume is associated with greater serum levels of BDNF, a mediator of neurogenesis in the dentate gyrus. Hippocampal volume declined in the control group, but higher preintervention fitness partially attenuated the decline, suggesting that fitness protects against volume loss. Caudate nucleus and thalamus volumes were unaffected by the intervention. These theoretically important findings indicate that aerobic exercise training is effective at reversing hippocampal volume loss in late adulthood, which is accompanied by improved memory function.

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.

The influence of aerobic fitness on cerebral white matter integrity and cognitive function in older adults: results of a one-year exercise intervention.

Cerebral white matter (WM) degeneration occurs with increasing age and is associated with declining cognitive function. Research has shown that cardiorespiratory fitness and exercise are effective as protective, even restorative, agents against cognitive and neurobiological impairments in older adults. In this study, we investigated whether the beneficial impact of aerobic fitness would extend to WM integrity in the context of a one-year exercise intervention. Further, we examined the pattern of diffusivity changes to better understand the underlying biological mechanisms. Finally, we assessed whether training-induced changes in WM integrity would be associated with improvements in cognitive performance independent of aerobic fitness gains. Results showed that aerobic fitness training did not affect group-level change in WM integrity, executive function, or short-term memory, but that greater aerobic fitness derived from the walking program was associated with greater change in WM integrity in the frontal and temporal lobes, and greater improvement in short-term memory. Increases in WM integrity, however, were not associated with short-term memory improvement, independent of fitness improvements. Therefore, while not all findings are consistent with previous research, we provide novel evidence for correlated change in training-induced aerobic fitness, WM integrity, and cognition among healthy 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.

The association between aerobic fitness and executive function is mediated by prefrontal cortex volume.

Aging is marked by a decline in cognitive function, which is often preceded by losses in gray matter volume. Fortunately, higher cardiorespiratory fitness (CRF) levels are associated with an attenuation of age-related losses in gray matter volume and a reduced risk for cognitive impairment. Despite these links, we have only a rudimentary understanding of whether fitness-related increases in gray matter volume lead to elevated cognitive function. In this cross-sectional study, we examined whether the association between higher aerobic fitness levels and elevated executive function was mediated by greater gray matter volume in the prefrontal cortex (PFC). One hundred and forty-two older adults (mean age=66.6 years) completed structural magnetic resonance imaging (MRI) scans, CRF assessments, and performed Stroop and spatial working memory (SPWM) tasks. Gray matter volume was assessed using an optimized voxel-based morphometry approach. Consistent with our predictions, higher fitness levels were associated with: (a) better performance on both the Stroop and SPWM tasks, and (b) greater gray matter volume in several regions, including the dorsolateral PFC (DLPFC). Volume of the right inferior frontal gyrus and precentral gyrus mediated the relationship between CRF and Stroop interference while a non-overlapping set of regions bilaterally in the DLPFC mediated the association between CRF and SPWM accuracy. These results suggest that specific regions of the DLPFC differentially relate to inhibition and spatial working memory. Thus, fitness may influence cognitive function by reducing brain atrophy in targeted areas in healthy older adults.

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.

Construct validation of a non-exercise measure of cardiorespiratory fitness in older adults.

BACKGROUND: Cardiorespiratory fitness (CRF) is associated with a decreased risk of all-cause mortality but is rarely assessed in medical settings due to burdens of time, cost, risk, and resources. The purpose of this study was to test the construct validity of a regression equation developed by Jurca and colleagues (2005) to estimate CRF without exercise testing in community dwelling older adults. METHODS: Participants (n = 172) aged 60 to 80 years with no contraindications to submaximal or maximal exercise testing completed a maximal graded exercise test (GXT) and the submaximal Rockport 1-mile walk test on separate occasions. Data included in the regression equation (age, sex, body mass index, resting heart rate, and physical activity) were obtained via measurement or self-report. Participants also reported presence of cardiovascular conditions. RESULTS: The multiple R for the regression equation was .72, p < .001 and CRF estimated from this equation was significantly correlated with the MET value from the GXT (r = 0.66) and with CRF estimated from submaximal field testing (r = 0.67). All three CRF indices were significantly and inversely associated with reporting more cardiovascular conditions. CONCLUSIONS: This research provides preliminary evidence that a non-exercise estimate of CRF is at least as valid as field test estimates of CRF and represents a low-risk, low-cost, and expedient method for estimating fitness in older adults.

Changes in cognitive function after a 12-week exercise intervention in adults with Down syndrome.

BACKGROUND: Between 250,000 and 400,000 individuals in the United States are diagnosed with Down syndrome (DS). Nearly all adults with DS will develop Alzheimer's disease pathology starting in their thirties. Recent studies suggest that increased physical activity (PA) may be important for maintaining components of cognition, including memory. OBJECTIVE: The purpose of this study was to evaluate changes in cognitive function after completion of a 12-week exercise intervention in adults with DS. METHODS: Participants were randomized to attend 30-minute group exercise sessions 1 or 2 times a week for 12 weeks. The exercise sessions were delivered via video conferencing on a tablet computer to groups of 5-8 participants. Sessions consisted of aerobic based exercises such as walking and jogging to music, dancing, as well as strength based exercises such as vertical jumps, bicep curls, and squats. Cognitive function was measured at baseline and end of study using the Cantab Dementia Battery for iPads, which assessed the cognitive domains of memory, attention, and reaction time. RESULTS: Twenty-seven participants (27.9 ±â€¯7.1 years of age, 40.7% female) enrolled and completed the 12-week intervention. Participants randomized to 1 session/week averaged 26.6 ±â€¯3.0 min/week of PA from the group exercise session. Participants randomized to 2 sessions/week averaged 57.7 ±â€¯15.3 min/week of PA from the group exercise sessions. Participants improved their performance on the two memory variables (p = 0.048 and p = 0.069). CONCLUSION: Increased exercise may have positive changes on memory and other cognitive functions.

Remote Exercise for Adults with Down Syndrome.

PURPOSE: Adults with Down syndrome are less physically active than their typically developed peers. The purpose of this study was to assess the feasibility of delivering moderate-to- vigorous exercise sessions, led by a trained health educator using real-time video conferencing, to groups of young adults with Down syndrome in their homes. METHODS: Participants were randomized to 30-minute group exercise sessions either 1 or 2 times a week delivered on an iPad mini tablet computer using the Zoom video conferencing application, and were asked to attend individual support/education sessions once a week using FaceTime® on the iPad, for 12 weeks. Minutes of MVPA during all group sessions were assessed using a Fitbit Charge HR activity/heart rate monitor. Participants were also asked to complete weekly homework assignments involving MVPA. RESULTS: Twenty-seven participants (n = 14,1 session·wk-1, n =13, 2 sessions·wk-1), mean age 27.9 ± 7.1 yrs., ~ 41% female, enrolled in and completed the 12-wk. intervention. Attendance at group exercise and individual support/education sessions did not differ significantly between those randomized to 1 (exercise sessions =89.9 ± 8.8%, support/education sessions = 81.2 ±18.7%) or 2 sessions·wk-1 (exercise sessions = 88.8 ± 7.7%; p=0.79, support/education sessions= 86.0 ± 20.9%; p=0.87). Participants averaged 27.7 ± 5.7 mins·session-1 of MVPA with no significant difference between the 1 (26.6 ± 3.0 mins·session-1) and 2 session·wk-1 groups (28.8 ± 7.7 mins·session-1, p=0.16). The completion rate for homework assignments did not differ significantly between the 1 (21.4 ± 26.3%) and 2 session·wk-1 groups (37.7 ± 21.7%, p=0.28). CONCLUSION: Exercise delivered by group video conferencing may be a feasible and potentially effective approach for increasing MVPA in adults with Down syndrome.

Does the method of weight loss effect long-term changes in weight, body composition or chronic disease risk factors in overweight or obese adults? A systematic review.

BACKGROUND: Differences in biological changes from weight loss by energy restriction and/or exercise may be associated with differences in long-term weight loss/regain. OBJECTIVE: To assess the effect of weight loss method on long-term changes in weight, body composition and chronic disease risk factors. DATA SOURCES: PubMed and Embase were searched (January 1990-October 2013) for studies with data on the effect of energy restriction, exercise (aerobic and resistance) on long-term weight loss. Twenty articles were included in this review. STUDY ELIGIBILITY CRITERIA: Primary source, peer reviewed randomized trials published in English with an active weight loss period of >6 months, or active weight loss with a follow-up period of any duration, conducted in overweight or obese adults were included. STUDY APPRAISAL AND SYNTHESIS METHODS: Considerable heterogeneity across trials existed for important study parameters, therefore a meta-analysis was considered inappropriate. Results were synthesized and grouped by comparisons (e.g. diet vs. aerobic exercise, diet vs. diet + aerobic exercise etc.) and study design (long-term or weight loss/follow-up). RESULTS: Forty percent of trials reported significantly greater long-term weight loss with diet compared with aerobic exercise, while results for differences in weight regain were inconclusive. Diet+aerobic exercise resulted in significantly greater weight loss than diet alone in 50% of trials. However, weight regain (∼ 55% of loss) was similar in diet and diet+aerobic exercise groups. Fat-free mass tended to be preserved when interventions included exercise.

Does increased exercise or physical activity alter ad-libitum daily energy intake or macronutrient composition in healthy adults? A systematic review.

BACKGROUND: The magnitude of the negative energy balance induced by exercise may be reduced due to compensatory increases in energy intake. OBJECTIVE: TO ADDRESS THE QUESTION: Does increased exercise or physical activity alter ad-libitum daily energy intake or macronutrient composition in healthy adults? DATA SOURCES: PubMed and Embase were searched (January 1990-January 2013) for studies that presented data on energy and/or macronutrient intake by level of exercise, physical activity or change in response to exercise. Ninety-nine articles (103 studies) were included. STUDY ELIGIBILITY CRITERIA: Primary source articles published in English in peer-reviewed journals. Articles that presented data on energy and/or macronutrient intake by level of exercise or physical activity or changes in energy or macronutrient intake in response to acute exercise or exercise training in healthy (non-athlete) adults (mean age 18-64 years). STUDY APPRAISAL AND SYNTHESIS METHODS: Articles were grouped by study design: cross-sectional, acute/short term, non-randomized, and randomized trials. Considerable heterogeneity existed within study groups for several important study parameters, therefore a meta-analysis was considered inappropriate. Results were synthesized and presented by study design. RESULTS: No effect of physical activity, exercise or exercise training on energy intake was shown in 59% of cross-sectional studies (n = 17), 69% of acute (n = 40), 50% of short-term (n = 10), 92% of non-randomized (n = 12) and 75% of randomized trials (n = 24). Ninety-four percent of acute, 57% of short-term, 100% of non-randomized and 74% of randomized trials found no effect of exercise on macronutrient intake. Forty-six percent of cross-sectional trials found lower fat intake with increased physical activity. LIMITATIONS: The literature is limited by the lack of adequately powered trials of sufficient duration, which have prescribed and measured exercise energy expenditure, or employed adequate assessment methods for energy and macronutrient intake. CONCLUSIONS: We found no consistent evidence that increased physical activity or exercise effects energy or macronutrient intake.

Physical activity is related to timing performance in older adults.

Physical activity has been linked to better cognitive function in older adults, especially for executive control processes. Researchers have suggested that temporal processing of durations less than 1 second is automatic and engages motor processes, while timing of longer durations engages executive processes. The purpose of this study was to determine whether a higher level of physical activity is associated with better reproduction performance in older adults, especially for durations in the "cognitive" range (i.e., longer than 1 s). Older right-handed adults completed a temporal reproduction task with five target durations (300, 650, 1000, 1350, and 1700 ms). Physical activity level was assessed via estimation of VO2 peak using a self-report activity scale. Results indicated that higher physical activity level was associated with better timing accuracy and that this effect was dependent on target duration. Namely, the relationship between physical activity and timing accuracy was strongest at the longest durations. Therefore, greater physical activity in older adults may have specific benefits linked to better executive functions.

The perceived importance of physical activity: associations with psychosocial and health-related outcomes.

BACKGROUND: The purpose of this study was to assess the extent to which participation in a 12-month exercise program changed the degree of importance that older adults attached to physical activity. In addition, associations among changes in physical activity importance and health-related and psychosocial outcomes were examined. METHODS: Community-dwelling older adults (N = 179) were recruited to participate in a 12-month exercise trial examining the association between changes in physical activity and fitness with changes in brain structure and psychological health. Participants were randomly assigned to a walking condition or a flexibility, toning, and balance condition. Physical, psychological, and cognitive assessments were taken at months 0, 6, and 12. RESULTS: Involvement in a 12-month exercise program increased the importance that participants placed on physical activity; this positive change was similar across exercise condition and sex. Changes in importance, however, were only associated with changes in physical health status and outcome expectations for exercise midway through the intervention. There were no significant associations at the end of the program. CONCLUSIONS: Regular participation in physical activity can positively influence the perceived importance of the behavior itself. Yet, the implications of such changes on physical activity-related outcomes remain equivocal and warrant further investigation.

The Midwest Exercise Trial for the Prevention of Weight Regain: MET POWeR.

Weight reduction in overweight and obese individuals results in physiological and behavioral changes that make the prevention of weight regain more difficult than either initial weight loss or the prevention of weight gain. Exercise is recommended for the prevention of weight regain by both governmental agencies and professional organizations. To date, the effectiveness of exercise recommendations for the prevention of weight regain has not been evaluated in a properly designed, adequately powered trial. Therefore, we will conduct a randomized trial to evaluate the effectiveness of 3 levels of exercise on the prevention of weight regain, in initially overweight and obese sedentary men and women. Participants will complete a 3 month weight loss intervention of decreased energy intake (EI) and increased exercise (100 min/week). Participants achieving clinically significant weight loss (≥ 5% of initial weight), will then be randomly assigned to 12 months of verified exercise at 3 levels (150, 225 or 300 min/week). This study will evaluate: 1) the effectiveness of 3 levels of exercise on the prevention of weight regain over 12 months subsequent to clinically significant weight loss (≥ 5%); 2) gender differences in weight regain in response to 3 levels of exercise; and 3) potential compensatory changes in daily physical activity (PA) and EI on weight regain in response to the 3 levels of exercise. The results of this investigation will provide information to develop evidence-based recommendations for the level of exercise associated with the prevention of weight regain.

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.

Beyond vascularization: aerobic fitness is associated with N-acetylaspartate and working memory.

Aerobic exercise is a promising form of prevention for cognitive decline; however, little is known about the molecular mechanisms by which exercise and fitness impacts the human brain. Several studies have postulated that increased regional brain volume and function are associated with aerobic fitness because of increased vascularization rather than increased neural tissue per se. We tested this position by examining the relationship between cardiorespiratory fitness and N-acetylaspartate (NAA) levels in the right frontal cortex using magnetic resonance spectroscopy. NAA is a nervous system specific metabolite found predominantly in cell bodies of neurons. We reasoned that if aerobic fitness was predominantly influencing the vasculature of the brain, then NAA levels should not vary as a function of aerobic fitness. However, if aerobic fitness influences the number or viability of neurons, then higher aerobic fitness levels might be associated with greater concentrations of NAA. We examined NAA levels, aerobic fitness, and cognitive performance in 137 older adults without cognitive impairment. Consistent with the latter hypothesis, we found that higher aerobic fitness levels offset an age-related decline in NAA. Furthermore, NAA mediated an association between fitness and backward digit span performance, suggesting that neuronal viability as measured by NAA is important in understanding fitness-related cognitive enhancement. Since NAA is found exclusively in neural tissue, our results indicate that the effect of fitness on the human brain extends beyond vascularization; aerobic fitness is associated with neuronal viability in the frontal cortex of older adults.

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.