Location-specific psychosocial and environmental correlates of physical activity and sedentary time in young adolescents: preliminary evidence for location-specific approaches from a cross-sectional observational study.

BACKGROUND: A better understanding of the extent to which psychosocial and environmental correlates of physical activity are specific to locations would inform intervention optimization. PURPOSE: To investigate cross-sectional associations of location-general and location-specific variables with physical activity and sedentary time in three common locations adolescents spend time. METHODS: Adolescents (N = 472,Mage = 14.1,SD = 1.5) wore an accelerometer and global positioning systems (GPS) tracker and self-reported on psychosocial (e.g., self-efficacy) and environmental (e.g., equipment) factors relevant to physical activity and sedentary time. We categorized each survey item based on whether it was specific to a location to generate psychosocial and environmental indices that were location-general or specific to either school, non-school, or home location. Physical activity (MVPA) and sedentary time were based on time/location match to home, school, or all "other" locations. Mixed-effects models investigated the relation of each index with location-specific activity. RESULTS: The location-general and non-school physical activity psychosocial indices were related to greater MVPA at school and "other" locations. The school physical activity environment index was related to greater MVPA and less sedentary time at school. The home activity environment index was related to greater MVPA at home. The non-school sedentary psychosocial index was related to less sedentary time at home. Interactions among indices revealed adolescents with low support on one index benefited (i.e., exhibited more optimal behavior) from high support on another index (e.g., higher scores on the location-general PA psychosocial index moderated lower scores on the home PA environment index). Concurrent high support on two indices did not provide additional benefit. CONCLUSIONS: No psychosocial or environment indices, including location-general indices, were related to activity in all locations. Most of the location-specific indices were associated with activity in the matching location(s). These findings provide preliminary evidence that psychosocial and environmental correlates of activity are location specific. Future studies should further develop location-specific measures and evaluate these constructs and whether interventions may be optimized by targeting location-specific psychosocial and environmental variables across multiple locations.

Sedentary behavior and cardiovascular disease in older women: The Objective Physical Activity and Cardiovascular Health (OPACH) Study.

Background: Evidence that higher sedentary time is associated with higher risk for cardiovascular disease (CVD) is based mainly on self-reported measures. Few studies have examined whether patterns of sedentary time are associated with higher risk for CVD. Methods: Women from the Objective Physical Activity and Cardiovascular Health (OPACH) Study (n=5638, aged 63-97, mean age=79±7) with no history of myocardial infarction (MI) or stroke wore accelerometers for 4-to-7 days and were followed for up to 4.9 years for CVD events. Average daily sedentary time and mean sedentary bout duration were the exposures of interest. Cox regression models estimated hazard ratios (HR) and 95% confidence intervals (CI) for CVD using models adjusted for covariates and subsequently adjusted for potential mediators (body mass index (BMI), diabetes, hypertension, and CVD-risk biomarkers [fasting glucose, high-density lipoprotein, triglycerides, and systolic blood pressure]). Restricted cubic spline regression characterized dose-response relationships. Results: There were 545 CVD events during 19,350 person-years. Adjusting for covariates, women in the highest (≥ ~11 hr/day) vs. the lowest (≤ ~9 hr/day) quartile of sedentary time had higher risk for CVD (HR=1.62; CI=1.21-2.17; p-trend <0.001). Further adjustment for potential mediators attenuated but did not eliminate significance of these associations (p-trend<.05, each). Longer vs. shorter mean bout duration was associated with higher risks for CVD (HR=1.54; CI=1.27-2.02; p-trend=0.003) after adjustment for covariates. Additional adjustment for CVD-risk biomarkers attenuated associations resulting in a quartile 4 vs. quartile 1 HR=1.36; CI=1.01-1.83; p-trend=0.10). Dose-response associations of sedentary time and bout duration with CVD were linear (P-nonlinear >0.05, each). Women jointly classified as having high sedentary time and long bout durations had significantly higher risk for CVD (HR=1.34; CI=1.08-1.65) than women with both low sedentary time and short bout duration. All analyses were repeated for incident coronary heart disease (MI or CVD death) and associations were similar with notably stronger hazard ratios. Conclusions: Both high sedentary time and long mean bout durations were associated in a dose-response manner with increased CVD risk in older women, suggesting that efforts to reduce CVD burden may benefit from addressing either or both component(s) of sedentary behavior.

Built Environment, Physical Activity, and Obesity: Findings from the International Physical Activity and Environment Network (IPEN) Adult Study.

Creating more physical activity-supportive built environments is recommended by the World Health Organization for controlling noncommunicable diseases. The IPEN (International Physical Activity and Environment Network) Adult Study was undertaken to provide international evidence on associations of built environments with physical activity and weight status in 12 countries on 5 continents (n > 14,000). This article presents reanalyzed data from eight primary papers to identify patterns of findings across studies. Neighborhood environment attributes, whether measured objectively or by self-report, were strongly related to all physical activity outcomes (accelerometer-assessed total physical activity, reported walking for transport and leisure) and meaningfully related to overweight/obesity. Multivariable indexes of built environment variables were more strongly related to most outcomes than were single-environment variables. Designing activity-supportive built environments should be a higher international health priority. Results provide evidence in support of global initiatives to increase physical activity and control noncommunicable diseases while achieving sustainable development goals.

Differences in adolescent activity and dietary behaviors across home, school, and other locations warrant location-specific intervention approaches.

BACKGROUND: Investigation of physical activity and dietary behaviors across locations can inform "setting-specific" health behavior interventions and improve understanding of contextual vulnerabilities to poor health. This study examined how physical activity, sedentary time, and dietary behaviors differed across home, school, and other locations in young adolescents. METHODS: Participants were adolescents aged 12-16 years from the Baltimore-Washington, DC and the Seattle areas from a larger cross-sectional study. Participants (n = 472) wore an accelerometer and Global Positioning Systems (GPS) tracker (Mean days = 5.12, SD = 1.62) to collect location-based physical activity and sedentary data. Participants (n = 789) completed 24-h dietary recalls to assess dietary behaviors and eating locations. Spatial analyses were performed to classify daily physical activity, sedentary time patterns, and dietary behaviors by location, categorized as home, school, and "other" locations. RESULTS: Adolescents were least physically active at home (2.5 min/hour of wear time) and school (2.9 min/hour of wear time) compared to "other" locations (5.9 min/hour of wear time). Participants spent a slightly greater proportion of wear time in sedentary time when at school (41 min/hour of wear time) than at home (39 min/hour of wear time), and time in bouts lasting ≥30 min (10 min/hour of wear time) and mean sedentary bout duration (5 min) were highest at school. About 61% of daily energy intake occurred at home, 25% at school, and 14% at "other" locations. Proportionately to energy intake, daily added sugar intake (5 g/100 kcal), fruits and vegetables (0.16 servings/100 kcal), high calorie beverages (0.09 beverages/100 kcal), whole grains (0.04 servings/100 kcal), grams of fiber (0.65 g/100 kcal), and calories of fat (33 kcal/100 kcal) and saturated fat (12 kcal/100 kcal) consumed were nutritionally least favorable at "other" locations. Daily sweet and savory snacks consumed was highest at school (0.14 snacks/100 kcal). CONCLUSIONS: Adolescents' health behaviors differed based on the location/environment they were in. Although dietary behaviors were generally more favorable in the home and school locations, physical activity was generally low and sedentary time was higher in these locations. Health behavior interventions that address the multiple locations in which adolescents spend time and use location-specific behavior change strategies should be explored to optimize health behaviors in each location.

Reducing Sitting Time in Obese Older Adults: The I-STAND Randomized Controlled Trial.

BACKGROUND: The authors tested the efficacy of the "I-STAND" intervention for reducing sitting time, a novel and potentially health-promoting approach, in older adults with obesity. METHODS: The authors recruited 60 people (mean age = 68 ± 4.9 years, 68% female, 86% White; mean body mass index = 35.4). The participants were randomized to receive the I-STAND sitting reduction intervention (n = 29) or healthy living control group (n = 31) for 12 weeks. At baseline and at 12 weeks, the participants wore activPAL devices to assess sitting time (primary outcome). Secondary outcomes included fasting glucose, blood pressure, and weight. Linear regression models assessed between-group differences in the outcomes. RESULTS: The I-STAND participants significantly reduced their sitting time compared with the controls (-58 min per day; 95% confidence interval [-100.3, -15.6]; p = .007). There were no statistically significant changes in the secondary outcomes. CONCLUSION: I-STAND was efficacious in reducing sitting time, but not in changing health outcomes in older adults with obesity.

Changes in Moderate Intensity Physical Activity Are Associated With Better Cognition in the Multilevel Intervention for Physical Activity in Retirement Communities (MIPARC) Study.

OBJECTIVE: The authors investigated if the physical activity increases observed in the Multilevel Intervention for Physical Activity in Retirement Communities (MIPARC) improved cognitive functions in older adults. The authors also examined if within-person changes in moderate to vigorous physical activity (MVPA), as opposed to low-light and high-light physical activity, were related to cognitive improvements in the entire sample. METHODS: This was a cluster randomized control trial set in retirement communities in San Diego County, CA. A total of 307 older adults without a formal diagnosis of dementia (mean age: 83 years; age range: 67-100; standard deviation: 6.4 years; 72% women) were assigned to the physical activity (N = 151) or healthy education control (N = 156) groups. Interventions were led by study staff for the first 6 months and sustained by peer leaders for the next 6 months. Components included individual counseling and self-monitoring with pedometers, group education sessions, and printed materials. Measurements occurred at baseline, 6 months, and 12 months. Triaxial accelerometers measured physical activity for 1 week. The Trail Making Test (TMT) Parts A and B and a Symbol Search Test measured cognitive functions. RESULTS: There were no significant differences in cognitive functions between the MIPARC intervention and control groups at 6 or 12 months. Within-person increases in MVPA, and not low-light or high-light physical activity, were associated with improvements in TMT Parts B, B-A, and Symbol Search scores in the entire sample. CONCLUSION: Findings suggest that MVPA may have a stronger impact on cognitive functions than lower intensity physical activity within retirement community samples of highly educated older adults without dementia.

Associations of built environment and proximity of food outlets with weight status: Analysis from 14 cities in 10 countries.

The study aimed to examine associations of neighborhood built environments and proximity of food outlets (BE measures) with body weight status using pooled data from an international study (IPEN Adult). Objective BE measures were calculated using geographic information systems for 10,008 participants (4463 male, 45%) aged 16-66 years in 14 cities. Participants self-reported proximity to three types of food outlets. Outcomes were body mass index (BMI) and overweight/obesity status. Male and female weight status associations with BE measures were estimated by generalized additive mixed models. Proportion (95% CI) of overweight (BMI 25 to <30) ranged from 16.6% (13.1, 19.8) to 41.1% (37.3, 44.7), and obesity (BMI ≥ 30) from 2.9% (1.3, 4.4) to 31.3% (27.7, 34.7), with Hong Kong being the lowest and Cuernavaca, Mexico highest for both proportions. Results differed by sex. Greater street intersection density, public transport density and perceived proximity to restaurants (males) were associated with lower odds of overweight/obesity (BMI ≥ 25). Proximity to public transport stops (females) was associated with higher odds of overweight/obesity. Composite BE measures were more strongly related to BMI and overweight/obesity status than single variables among men but not women. One standard deviation improvement in the composite measures of BE was associated with small reductions of 0.1-0.5% in BMI but meaningful reductions of 2.5-5.3% in the odds of overweight/obesity. Effects were linear and generalizable across cities. Neighborhoods designed to support public transport, with food outlets within walking distance, may contribute to global obesity control.

Dimensions of sedentary behavior and objective cognitive functioning in breast cancer survivors.

PURPOSE: To examine associations between dimensions of sedentary behavior and cognitive function in breast cancer survivors. METHODS: Sedentary behavior variables were measured using thigh-worn activPALs, and included total daily sitting time, time in long sitting bouts, sit-to-stand transitions, and standing time. Cognitive function was assessed using the NIH Toolbox Cognitive Domain. Separate multivariable linear regression models were used to examine associations between sedentary behavior variables with the cognitive domain scores of attention, executive functioning, episodic memory, working memory, and information processing speed. RESULTS: Thirty breast cancer survivors with a mean age of 62.2 (SD = 7.8) years who were 2.6 (SD = 1.1) years since diagnosis completed study assessments. In multivariable linear regression models, more time spent standing was associated with faster information processing (b: 5.78; p = 0.03), and more time spent in long sitting bouts was associated with worse executive function (b: -2.82; p = 0.02), after adjustment for covariates. No other sedentary behavior variables were statistically significantly associated with the cognitive domains examined in this study. CONCLUSIONS: Two important sedentary constructs that are amenable to intervention, including time in prolonged sitting bouts and standing time, may be associated with cognitive function in breast cancer survivors. More research is needed to determine whether modifying these dimensions of sedentary behavior will improve cognitive function in women with a history of breast cancer, or prevent it from declining in breast cancer patients.

Protocol for a cross sectional study of cancer risk, environmental exposures and lifestyle behaviors in a diverse community sample: the Community of Mine study.

BACKGROUND: Physical inactivity and unhealthy diet are modifiable behaviors that lead to several cancers. Biologically, these behaviors are linked to cancer through obesity-related insulin resistance, inflammation, and oxidative stress. Individual strategies to change physical activity and diet are often short lived with limited effects. Interventions are expected to be more successful when guided by multi-level frameworks that include environmental components for supporting lifestyle changes. Understanding the role of environment in the pathways between behavior and cancer can help identify what environmental conditions are needed for individual behavioral change approaches to be successful, and better recognize how environments may be fueling underlying racial and ethnic cancer disparities. METHODS: This cross-sectional study was designed to select participants (n = 602 adults, 40% Hispanic, in San Diego County) from a range of neighborhoods ensuring environmental variability in walkability and food access. Biomarkers measuring cancer risk were measured with fasting blood draw including insulin resistance (fasting plasma insulin and glucose levels), systemic inflammation (levels of CRP), and oxidative stress measured from urine samples. Objective physical activity, sedentary behavior, and sleep were measured by participants wearing a GT3X+ ActiGraph on the hip and wrist. Objective measures of locations were obtained through participants wearing a Qstarz Global Positioning System (GPS) device on the waist. Dietary measures were based on a 24-h food recall collected on two days (weekday and weekend). Environmental exposure will be calculated using static measures around the home and work, and dynamic measures of mobility derived from GPS traces. Associations of environment with physical activity, obesity, diet, and biomarkers will be measured using generalized estimating equation models. DISCUSSION: Our study is the largest study of objectively measured physical activity, dietary behaviors, environmental context/exposure, and cancer-related biomarkers in a Hispanic population. It is the first to perform high quality measures of physical activity, sedentary behavior, sleep, diet and locations in which these behaviors occur in relation to cancer-associated biomarkers including insulin resistance, inflammation, impaired lipid metabolism, and oxidative stress. Results will add to the evidence-base of how behaviors and the built environment interact to influence biomarkers that increase cancer risk. TRIAL REGISTRATION: ClinicalTrials.gov NCT02094170 , 03/21/2014.

A comparison of accelerometry analysis methods for physical activity in older adult women and associations with health outcomes over time.

This study compared five different methods for analyzing accelerometer-measured physical activity (PA) in older adults and assessed the relationship between changes in PA and changes in physical function and depressive symptoms for each method. Older adult females (N = 144, Mage = 83.3 ± 6.4yrs) wore hip accelerometers for six days and completed measures of physical function and depressive symptoms at baseline and six months. Accelerometry data were processed by five methods to estimate PA: 1041 vertical axis cut-point, 15-second vector magnitude (VM) cut-point, 1-second VM algorithm (Activity Index (AI)), machine learned walking algorithm, and individualized cut-point derived from a 400-meter walk. Generalized estimating equations compared PA minutes across methods and showed significant differences between some methods but not others; methods estimated 6-month changes in PA ranging from 4 minutes to over 20 minutes. Linear mixed models for each method tested associations between changes in PA and health. All methods, except the individualized cut-point, had a significant relationship between change in PA and improved physical function and depressive symptoms. This study is among the first to compare accelerometry processing methods and their relationship to health. It is important to recognize the differences in PA estimates and relationship to health outcomes based on data processing method. Abbreviation: Machine Learning (ML); Short Physical Performance Battery (SPPB); Center of Epidemiologic Studies Depression Scale (CES-D); Physical Activity (PA); Activity Index (AI); Activities of Daily Living (ADL).

Day-level sedentary pattern estimates derived from hip-worn accelerometer cut-points in 8-12-year-olds: Do they reflect postural transitions?

Improving sedentary measurement is critical to understanding sedentary-health associations in youth. This study assessed agreement between the thigh-worn activPAL and commonly used hip-worn ActiGraph accelerometer methods for assessing sedentary patterns in children. Both devices were worn by 8-12-year-olds (N = 195) for 4.6 ± 1.9 days. Two ActiGraph cut-points were applied to two epoch durations: ≤25 counts (c)/15 s, ≤75c/15s, ≤100c/60s, and ≤300c/60s. Bias, mean absolute deviation (MAD), and intraclass correlation coefficients (ICCs) tested agreement between devices for total sedentary time and 11 sedentary pattern variables (usual bout duration, sedentary time accumulated in various bout durations, breaks/day, break rate, and alpha). For most sedentary pattern variables, ActiGraph 25c/15s, 75c/15s, and 100c/60s had poor ICCs, with bias and MAD >20%. ActiGraph 300c/60s had a better agreement than the other cut-points, but all ICCs were <0.587. ActiGraph underestimated sedentary time in longer bouts and usual bout duration, and overestimated sedentary time in shorter bouts, breaks/day, and alpha. For total sedentary time, ActiGraph 25c/15s, 300c/60s, and 75c/15s had good/fair ICCs, with bias and MAD <20%. Sedentary patterns derived from two commonly used ActiGraph cut-points did not appear to reflect postural changes. These differences between measurement devices should be considered when interpreting findings from sedentary pattern studies.

Cluster randomized controlled trial of a multilevel physical activity intervention for older adults.

BACKGROUND: Older adults are the least active population group. Interventions in residential settings may support a multi-level approach to behavior change. METHODS: In a cluster randomized control trial, 11 San Diego retirement communities were assigned to a physical activity (PA) intervention or a healthy aging attention control condition. Participants were 307 adults over 65 years old. The multilevel PA intervention was delivered with the assistance of peer leaders, who were trained older adult from the retirement communities. Intervention components included individual counseling & self-monitoring with pedometers, group education sessions, group walks, community advocacy and pedestrian community change projects. Intervention condition by time interactions were tested using generalized mixed effects regressions. The primary outcomes was accelerometer measured physical activity. Secondary outcomes were blood pressure and objectively measured physical functioning. RESULTS: Over 70% of the sample were 80 years or older. PA significantly increased in the intervention condition (56 min of moderate-vigorous PA per week; 119 min of light PA) compared with the control condition and remained significantly higher across the 12 month study. Men and participants under 84 years old benefited most from the intervention. There was a significant decrease in systolic (p < .007) and diastolic (p < .02) blood pressure at 6 months. Physical functioning improved but the changes were not statistically significant. CONCLUSIONS: Intervention fidelity was high demonstrating feasibility. Changes in PA and blood pressure achieved were comparable to other studies with much younger participants. Men, in particular, avoided a year-long decline in PA. TRIAL REGISTRATION: clincialtrials.gov Identifier: NCT01155011 .

Neighborhood built environment and socioeconomic status in relation to physical activity, sedentary behavior, and weight status of adolescents.

INTRODUCTION: The study examined the association of neighborhood walkability to multiple activity-related outcomes and BMI among adolescents and evaluated socioeconomic status as an effect modifier. METHOD: Cross-sectional study, with adolescents recruited from neighborhoods that met criteria for a 2 × 2 matrix defined by high/low GIS-defined walkability and high/low median income. Adolescents aged 12-16 years (n = 928) were recruited from selected neighborhoods in Maryland and King County, Washington regions in 2009-2011. There were 50.4% girls, and 66.3% were non-Hispanic white, with no medical restrictions on physical activity (PA) or diets. Total PA and sedentary time was assessed by 7 days of accelerometer monitoring. Adolescents self-reported active transport, time spent on 6 sedentary behaviors, and height and weight, used to compute BMI percentiles. Mixed model linear and logistic regressions examined outcomes for association with walkability and income, adjusting for demographic covariates and clustering within block groups. RESULTS: Walkability was positively and significantly related to objectively-measured PA (p < .001) and more frequent walking for transportation (p < .001). Total self-reported sedentary time (p = .048) and TV time (p < .007) were negatively related to walkability. Time in vehicles was negatively related to walkability only among higher-income adolescents. CONCLUSIONS: Neighborhood walkability was strongly and consistently associated with adolescents' objectively-assessed total physical activity and reported active transportation. A novel finding was that adolescents living in walkable neighborhoods reported less television time and less time in vehicles. Most results were similar across income categories. Results strengthen the rationale for recommendations to improve walkability.

Just-in-Time Feedback in Diet and Physical Activity Interventions: Systematic Review and Practical Design Framework.

BACKGROUND: The integration of body-worn sensors with mobile devices presents a tremendous opportunity to improve just-in-time behavioral interventions by enhancing bidirectional communication between investigators and their participants. This approach can be used to deliver supportive feedback at critical moments to optimize the attainment of health behavior goals. OBJECTIVE: The goals of this systematic review were to summarize data on the content characteristics of feedback messaging used in diet and physical activity (PA) interventions and to develop a practical framework for designing just-in-time feedback for behavioral interventions. METHODS: Interventions that included just-in-time feedback on PA, sedentary behavior, or dietary intake were eligible for inclusion. Feedback content and efficacy data were synthesized descriptively. RESULTS: The review included 31 studies (15/31, 48%, targeting PA or sedentary behavior only; 13/31, 42%, targeting diet and PA; and 3/31, 10%, targeting diet only). All studies used just-in-time feedback, 30 (97%, 30/31) used personalized feedback, and 24 (78%, 24/31) used goal-oriented feedback, but only 5 (16%, 5/31) used actionable feedback. Of the 9 studies that tested the efficacy of providing feedback to promote behavior change, 4 reported significant improvements in health behavior. In 3 of these 4 studies, feedback was continuously available, goal-oriented, or actionable. CONCLUSIONS: Feedback that was continuously available, personalized, and actionable relative to a known behavioral objective was prominent in intervention studies with significant behavior change outcomes. Future research should determine whether all or some of these characteristics are needed to optimize the effect of feedback in just-in-time interventions.

Defining Accelerometer Nonwear Time to Maximize Detection of Sedentary Time in Youth.

PURPOSE: The present study examined various accelerometer nonwear definitions and their impact on detection of sedentary time using different ActiGraph models, filters, and axes. METHODS: In total, 61 youth (34 children and 27 adolescents; aged 5-17 y) wore a 7164 and GT3X+ ActiGraph on a hip-worn belt during a 90-minute structured sedentary activity. Data from GT3X+ were downloaded using the Normal filter (N) and low-frequency extension (LFE), and vertical axis (V) and vector magnitude (VM) counts were examined. Nine nonwear definitions were applied to the 7164 model (V), GT3X+LFE (V and VM), and GT3X+N (V and VM), and sedentary estimates were computed. RESULTS: The GT3X+LFE-VM was most sensitive to movement and could accurately detect observed sedentary time with the shortest nonwear definition of 20 minutes of consecutive "0" counts for children and 40 minutes for adolescents. The GT3X+N-V was least sensitive to movement and required longer definitions to detect observed sedentary time (40 min for children and 90 min for adolescents). VM definitions were 10 minutes shorter than V definitions. LFE definitions were 40 minutes shorter than N definitions in adolescents. CONCLUSION: Different nonwear definitions are needed for children and adolescents and for different model-filter-axis types. Authors need to consider nonwear definitions when comparing prevalence rates of sedentary behavior across studies.

Physical activity, sedentary behaviour, diet, and cancer: an update and emerging new evidence.

The lifestyle factors of physical activity, sedentary behaviour, and diet are increasingly being studied for their associations with cancer. Physical activity is inversely associated with and sedentary behaviour is positively (and independently) associated with an increased risk of more than ten types of cancer, including colorectal cancer (and advanced adenomas), endometrial cancers, and breast cancer. The most consistent dietary risk factor for premalignant and invasive breast cancer is alcohol, whether consumed during early or late adult life, even at low levels. Epidemiological studies show that the inclusion of wholegrain, fibre, fruits, and vegetables within diets are associated with reduced cancer risk, with diet during early life (age <8 years) having the strongest apparent association with cancer incidence. However, randomised controlled trials of diet-related factors have not yet shown any conclusive associations between diet and cancer incidence. Obesity is a key contributory factor associated with cancer risk and mortality, including in dose-response associations in endometrial and post-menopausal breast cancer, and in degree and duration of fatty liver disease-related hepatocellular carcinoma. Obesity produces an inflammatory state, characterised by macrophages clustered around enlarged hypertrophied, dead, and dying adipocytes, forming crown-like structures. Increased concentrations of aromatase and interleukin 6 in inflamed breast tissue and an increased number of macrophages, compared with healthy tissue, are also observed in women with normal body mass index, suggesting a metabolic obesity state. Emerging randomised controlled trials of physical activity and dietary factors and mechanistic studies of immunity, inflammation, extracellular matrix mechanics, epigenetic or transcriptional regulation, protein translation, circadian disruption, and interactions of the multibiome with lifestyle factors will be crucial to advance this field.

Current Challenges and New Opportunities for Gene-Environment Interaction Studies of Complex Diseases.

Recently, many new approaches, study designs, and statistical and analytical methods have emerged for studying gene-environment interactions (G×Es) in large-scale studies of human populations. There are opportunities in this field, particularly with respect to the incorporation of -omics and next-generation sequencing data and continual improvement in measures of environmental exposures implicated in complex disease outcomes. In a workshop called "Current Challenges and New Opportunities for Gene-Environment Interaction Studies of Complex Diseases," held October 17-18, 2014, by the National Institute of Environmental Health Sciences and the National Cancer Institute in conjunction with the annual American Society of Human Genetics meeting, participants explored new approaches and tools that have been developed in recent years for G×E discovery. This paper highlights current and critical issues and themes in G×E research that need additional consideration, including the improved data analytical methods, environmental exposure assessment, and incorporation of functional data and annotations.

Physical activity in relation to urban environments in 14 cities worldwide: a cross-sectional study.

BACKGROUND: Physical inactivity is a global pandemic responsible for over 5 million deaths annually through its effects on multiple non-communicable diseases. We aimed to document how objectively measured attributes of the urban environment are related to objectively measured physical activity, in an international sample of adults. METHODS: We based our analyses on the International Physical activity and Environment Network (IPEN) adult study, which was a coordinated, international, cross-sectional study. Participants were sampled from neighbourhoods with varied levels of walkability and socioeconomic status. The present analyses of data from the IPEN adult study included 6822 adults aged 18-66 years from 14 cities in ten countries on five continents. Indicators of walkability, public transport access, and park access were assessed in 1·0 km and 0·5 km street network buffers around each participant's residential address with geographic information systems. Mean daily minutes of moderate-to-vigorous-intensity physical activity were measured with 4-7 days of accelerometer monitoring. Associations between environmental attributes and physical activity were estimated using generalised additive mixed models with gamma variance and logarithmic link functions. RESULTS: Four of six environmental attributes were significantly, positively, and linearly related to physical activity in the single variable models: net residential density (exp[b] 1·006 [95% CI 1·003-1·009]; p=0·001), intersection density (1·069 [1·011-1·130]; p=0·019), public transport density (1·037 [1·018-1·056]; p=0·0007), and number of parks (1·146 [1·033-1·272]; p=0·010). Mixed land use and distance to nearest public transport point were not related to physical activity. The difference in physical activity between participants living in the most and least activity-friendly neighbourhoods ranged from 68 min/week to 89 min/week, which represents 45-59% of the 150 min/week recommended by guidelines. INTERPRETATION: Design of urban environments has the potential to contribute substantially to physical activity. Similarity of findings across cities suggests the promise of engaging urban planning, transportation, and parks sectors in efforts to reduce the health burden of the global physical inactivity pandemic. FUNDING: Funding for coordination of the IPEN adult study, including the present analysis, was provided by the National Cancer Institute of National Institutes of Health (CA127296) with studies in each country funded by different sources.

Physical Activity in Older Adults: an Ecological Approach.

BACKGROUND: Studies identifying correlates of physical activity (PA) at all levels of the ecological model can provide an empirical basis for designing interventions to increase older adults' PA. PURPOSE: Applying ecological model principles, this study concurrently examined individual, psychosocial, and environmental correlates of older adults' PA to determine whether built environment factors contribute to PA over and above individual/demographic and psychosocial variables. METHODS: Using a cross-sectional observational design, 726 adults, aged ≥66 years, were recruited from two US regions. Explanatory variables included demographics, self-efficacy, social support, barriers, and environmental variables measured by using geographic information systems (GIS) and self-report. Outcomes included reported walking for errands and leisure/exercise and accelerometer-measured daily moderate to vigorous PA (MVPA). Analyses employed mixed-model regressions with backward elimination. RESULTS: For daily MVPA, the only significant environmental variable was GIS-based proximity to a park (p < 0.001) after controlling for individual/demographic and psychosocial factors. Walking for errands was positively related to four environmental variables: reported walking/cycling facilities (p < 0.05), GIS-based intersection density (p < 0.01), mixed land use (p < 0.01), and private recreation facilities (p < 0.01). Walking for leisure/exercise was negatively related to GIS-based mixed land use (p < 0.05). Non-Hispanic white race/ethnicity, self-efficacy, and social support positively related to all three PA outcomes (p < 0.05). CONCLUSIONS: Correlates of older adults' PA were found at all ecological levels, supporting multiple levels of influence and need for multilevel interventions. Environmental correlates varied by PA outcome. Walking for errands exhibited the most environmental associations.

Within-person associations of young adolescents' physical activity across five primary locations: is there evidence of cross-location compensation?

BACKGROUND: Youth are active in multiple locations, but it is unknown whether more physical activity in one location is associated with less in other locations. This cross-sectional study examines whether on days with more physical activity in a given location, relative to their typical activity in that location, youth had less activity in other locations (i.e., within-person associations/compensation). METHODS: Participants were 528 adolescents, ages 12 to 16 (M = 14.12, SD = 1.44, 50% boys, 70% White non-Hispanic). Accelerometer and Global Positioning System devices were used to measure the proportion of time spent in moderate-to-vigorous physical activity (MVPA) in five locations: home, home neighborhood, school, school neighborhood, and other locations. Mixed-effects regression was used to examine within-person associations of MVPA across locations and moderators of these associations. RESULTS: Two of ten within-participant associations tested indicated small amounts of compensation, and one association indicated generalization across locations. Higher at-school MVPA (relative to the participant's average) was related to less at-home MVPA and other-location MVPA (Bs = -0.06 min/day). Higher home-neighborhood MVPA (relative to the participant's average) was related to more at-home MVPA (B = 0.07 min/day). Some models showed that compensation was more likely (or generalization less likely) in boys and non-whites or Hispanic youth. CONCLUSIONS: Consistent evidence of compensation across locations was not observed. A small amount of compensation was observed for school physical activity, suggesting that adolescents partially compensated for high amounts of school activity by being less active in other locations. Conversely, home-neighborhood physical activity appeared to carry over into the home, indicating a generalization effect. Overall these findings suggest that increasing physical activity in one location is unlikely to result in meaningful decreases in other locations. Supporting physical activity across multiple locations is critical to increasing overall physical activity in youth.