Dan J. Graham

Patterns of Obesogenic Neighborhood Features and Adolescent Weight: A comparison of statistical approaches

BACKGROUND Few studies have addressed the potential influence of neighborhood characteristics on adolescent obesity risk, and findings have been inconsistent. PURPOSE Identify patterns among neighborhood food, physical activity, street/transportation, and socioeconomic characteristics and examine their associations with adolescent weight status using three statistical approaches. METHODS Anthropometric measures were taken on 2682 adolescents (53% female, mean age=14.5 years) from 20 Minneapolis/St. Paul MN schools in 2009-2010. Neighborhood environmental variables were measured using GIS data and by survey. Gender-stratified regressions related to BMI z-scores and obesity to (1) separate neighborhood variables; (2) composites formed using factor analysis; and (3) clusters identified using spatial latent class analysis in 2012. RESULTS Regressions on separate neighborhood variables found a low percentage of parks/recreation, and low perceived safety were associated with higher BMI z-scores in boys and girls. Factor analysis found five factors: away-from-home food and recreation accessibility, community disadvantage, green space, retail/transit density, and supermarket accessibility. The first two factors were associated with BMI z-score in girls but not in boys. Spatial latent class analysis identified six clusters with complex combinations of both positive and negative environmental influences. In boys, the cluster with highest obesity (29.8%) included low SES, parks/recreation, and safety; high restaurant and convenience store density; and nearby access to gyms, supermarkets, and many transit stops. CONCLUSIONS The mix of neighborhood-level barriers and facilitators of weight-related health behaviors leads to difficulties disentangling their associations with adolescent obesity; however, statistical approaches including factor and latent class analysis may provide useful means for addressing this complexity.

Personality, physical fitness, and affective response to exercise among adolescents.

PURPOSE Evidence shows that aspects of personality are associated with participation in physical activity. We hypothesized that, among adolescents, behavioral activation (BAS) and behavioral inhibition (BIS) systems would be associated with physical fitness (cardiovascular fitness and percent body fat), enjoyment of exercise, tolerance of and persistence in high-intensity exercise, and affective response to an acute exercise bout. METHODS One hundred and forty-six healthy adolescents completed a cardiovascular fitness test, percent body fat assessment (dual-energy x-ray absorptiometer), and two 30-min cycle ergometer exercise tasks at moderate and hard intensities. Questionnaires evaluated BIS/BAS, enjoyment of exercise, and preference and tolerance for high-intensity activity. Affect in response to exercise was assessed using the Feeling Scale (FS) and the Activation Deactivation Adjective Check List (AD ACL). RESULTS BIS was negatively correlated with cardiovascular fitness and tolerance for high-intensity exercise, and adolescents with high BIS scores reported more negative FS in response to exercise at both moderate and hard intensities. BAS was positively correlated with enjoyment of exercise, and adolescents with high BAS scores reported having more positive FS and higher energetic arousal on the AD ACL in response to moderate-intensity exercise. The association between BAS and affect was attenuated for the hard-intensity exercise task. CONCLUSION These findings suggest that both the drive to avoid punishing stimuli (BIS) and the drive to approach rewarding stimuli (BAS) are related to the affective response to exercise. The BIS may be more strongly associated with fitness-related exercise behavior among adolescents than the BAS, whereas the BAS may play a relatively greater role in terms of subjective exercise enjoyment.

Regional brain activation and affective response to physical activity among healthy adolescents

Research has shown that frontal brain activation, assessed via electroencephalographic (EEG) asymmetry, predicts the post-exercise affective response to exercise among adults. Building on this evidence, the present study investigates the utility of resting cortical asymmetry for explaining variance in the affective response both during and after exercise at two different intensities among healthy adolescents. Resting EEG was obtained from 98 adolescents (55% male), who also completed two 30-min exercise tasks on a cycle ergometer at a moderate and hard intensity. Affect (as measured by the Feeling Scale) was assessed prior to exercise, every 10min during exercise, immediately post-exercise, and 10min post-exercise. When moderate exercise was performed first, resting frontal cortical asymmetry was related to the affective response to moderate exercise, such that left-dominant adolescents reported more positive affect compared to right-dominant adolescents. When hard exercise was performed first, the association was not significant. The results are interpreted in light of current theory related to affect in response to exercise.

Multicontextual Correlates of Adolescent Leisure-Time Physical Activity

BACKGROUND Adolescent moderate to vigorous physical activity (MVPA) is influenced by many factors. MVPA-promotion interventions would fare better if these multiple determinants were better understood. PURPOSE To simultaneously assess overall and relative contributions of factors from personal, family, friend, school, and neighborhood contexts to adolescent MVPA. It was hypothesized that (1) key correlates would emerge in each context and (2) factors from more- versus less-proximal contexts would relate more strongly to MVPA. METHODS Students in grades 6-12 (n=2,793; mean age=14.4 [SD=2.0] years; 53% girls) were recruited from 20 Minnesota public schools in 2009-2010 to participate in the Eating and Activity in Teens 2010 study. Regression analyses conducted in 2013 examined factors related to weekly MVPA. Data were collected from adolescent participants, their parents and friends, school teachers and administrators, and GIS sources. RESULTS Fifty multicontextual factors explained 25% of MVPA variance for boys and 27% for girls. Personal factors (e.g., self-efficacy) were most predictive of MVPA, followed by social factors (e.g., support for PA); environmental factors (e.g., access to PA resources) were least predictive of adolescent PA. Gender differences emerged for several predictors (e.g., in mutually adjusted analyses, MVPA among girls, but not boys, related positively to distance to trails and MVPA among female friends and fathers, and related negatively to perceived barriers). CONCLUSIONS Stronger linkages exist between adolescent MVPA and more-proximal (personal, family, and friend) factors compared to more-distal (school and neighborhood) factors, suggesting the importance of working with adolescents, their families, and friends to promote PA.

Longitudinal changes in physical activity and sedentary behavior from adolescence to adulthood: Comparing U.S.-born and foreign-born populations

BACKGROUND This study compared moderate-to-vigorous physical activity (MVPA) and sedentary behavior in U.S.-born and foreign-born adolescents and young adults, and differences in behavior change from adolescence to young adulthood by nativity. METHODS Data on 2039 U.S.-born and 225 foreign-born participants from Project EAT-III (Eating and Activity in Teens and Young Adults) were used to examine MVPA, television/ DVD/video viewing, and computer use. Participants completed surveys at baseline in Minneapolis/St. Paul, MN secondary school classrooms in 1998-1999 (14.9 ± 1.6 y) and follow-up measures online or by mail in 2008-2009 (25.3 ± 1.6 y). RESULTS At both time points, foreign-born participants reported significantly lower levels of MVPA than their U.S.-born counterparts (P < .05). Foreign-born females at baseline and follow-up and foreign-born males at follow-up reported less television/DVD/video viewing compared with U.S.-born participants (P < .01). All participants experienced a significant decline in MVPA from baseline to follow-up (P < .001). Between-group analyses revealed a significantly greater decline in television/DVDs/video viewing for the foreign-born males compared with U.S.-born males from baseline to follow-up (mean change: foreign-born: -4.8 ± 1.32 hrs/wk, U.S.-born: -0.6 ± 0.6 hrs/wk; P < .01). CONCLUSIONS Differences in activity patterns between foreign-born and U.S.-born youth into young adulthood may contribute to disparities in chronic disease risk. Nativity, along with the social, environmental, and cultural context, should be considered when designing programs to promote MVPA and prevent obesity.

Environmental Modifications and 2-Year Measured and Self-reported Stair-Use: A Worksite Randomized Trial

Environmental modifications have been shown to increase short-term stair use, longer-term success is unclear. This study assessed the 2-year effectiveness of an environmental intervention promoting worksite stair use. We assessed stair use at work by means of self-reports and infrared beam counters (which send a safe and invisible beam of infrared light from one side of a stairwell to a reflector on the other side; when an individual uses the stairs, the infrared beam is disrupted and an instance of stair use is recorded) at six worksites (three intervention, three control) in a group randomized, controlled worksite weight-gain prevention trial in Minneapolis/St. Paul, MN. Intervention modifications were signs encouraging stair use, music, and art posters in stairwells. We collected data before environmental modifications (2006–2007) and at the end of the 2-year intervention (2008–2009). The intervention had a significant positive effect on stair use measured both objectively and via self-report, with greatest increases reported among those participants who used the stairs least at baseline. Following 2-years of continuously-maintained stairwell modifications, increases in both objectively-measured and self-reported stair use were significantly larger at intervention than control worksites. Study findings suggest that the positive impact of environmental modifications on stair use persist over a longer time period than has been previously demonstrated. Results also indicate that infrequent stair users may be most amenable to the behavior changes encouraged by these environmental enhancements.

Television Viewing: Moderator or Mediator of an Adolescent Physical Activity Intervention?:

Purpose. To determine whether the amount of television (TV) watched by participants enrolled in a physical activity intervention mediates or moderates program effectiveness. Design. Nine-month, controlled, school-based physical activity intervention. Setting. Public high school. Participants. One hundred twenty-two sedentary adolescent females (mean + standard deviation age = 15.04 + 0.79 years). Intervention. Supervised in-class exercise, health education, and internet-based self-monitoring. Measures. Physical activity by 3-day physical activity recall; TV viewing by self-reports; cardiovascular fitness by cycle ergometer. Analysis. T-tests were conducted to examine between-group differences. Linear regression equations tested the mediating or moderating role of TV watching relative to the intervention. Results. TV viewing moderated the interventions effect on vigorous activity; the intervention significantly predicted change in physical activity among high (β = −.45; p < .001), but not among low (p > .05), TV watchers. TV viewing did not mediate the intervention effect. Conclusions. Consistent with displacement theory, adolescents who watched more TV prior to the intervention showed postintervention increases in vigorous physical activity and concomitant decreases in TV viewing, whereas those who watched less TV showed no change in physical activity or TV viewing.

Maintenance-tailored therapy vs. standard behavior therapy for 30-month maintenance of weight loss.

OBJECTIVE To assess differences in weight regain one year after an 18-month obesity treatment with standard behavior therapy (SBT) or maintenance-tailored therapy for obesity (MTT). METHOD 213 obese adult volunteers were treated for 18 months using SBT with fixed behavioral prescriptions or MTT that employed varied behavioral prescriptions with treatment breaks. Follow-up analysis focused on weight maintenance after a year of no contact. The trial was conducted at the University of Minnesota between 2005 and 2009. RESULTS Mean (SD) weight change between 18 and 30 months for participants in the SBT group was +4.1 kg (4.4) compared to +2.8 kg (4.5) in the MTT group. This is a 31% reduction in weight regain in MTT relative to SBT (p=0.078). This trend toward better maintenance in MTT versus SBT was due primarily to superior differential maintenance in MTT participants in the highest tertile of total weight loss at 18 months, i.e. MTT participants in this tertile regained 4 kg less than SBT participants between 18 and 30 months. CONCLUSIONS The MTT approach with varied content and timing produced more desirable patterns of weight loss maintenance than the traditional SBT approach, especially among individuals who had achieved greater initial weight loss.

Impact of explained v. unexplained front-of-package nutrition labels on parent and child food choices: a randomized trial

OBJECTIVE The present study investigated whether parent/child pairs would select more healthful foods when: (i) products were labelled with front-of-package (FOP) nutrition labels relative to packages without labels; (ii) products were labelled with colour-coded Multiple Traffic Light (MTL) FOP labels relative to monochromatic Facts up Front (FuF) FOP labels; and (iii) FOP labels were explained via in-aisle signage v. unexplained. DESIGN Participants were randomly assigned to one of five conditions: (i) FuF labels with in-aisle signs explaining the labels; (ii) FuF labels, no signage; (iii) MTL labels with in-aisle signage; (iv) MTL labels, no signage; (v) control group, no labels/signage. Saturated fat, sodium, sugar and energy (calorie) content were compared across conditions. SETTING The study took place in a laboratory grocery aisle. SUBJECTS Parent/child pairs (n 153) completed the study. RESULTS Results did not support the hypothesis that MTL labels would lead to more healthful choices than FuF labels. The presence of FOP labels did little to improve the healthfulness of selected foods, with few exceptions (participants with v. without access to FOP labels selected lower-calorie cereals, participants with access to both FOP labels and in-aisle explanatory signage selected products with less saturated fat v. participants without explanatory signage). CONCLUSIONS Neither MTL nor FuF FOP labels led to food choices with significantly lower saturated fat, sodium or sugar. In-aisle signs explaining the FOP labels were somewhat helpful to consumers in making more healthful dietary decisions. New FOP labelling programmes could benefit from campaigns to increase consumer awareness and understanding of the labels.

Evaluating the Impact of U.S. Food and Drug Administration–Proposed Nutrition Facts Label Changes on Young Adults’ Visual Attention and Purchase Intentions

Background. The U.S. Food and Drug Administration (FDA) has proposed modifying the Nutrition Facts Label (NFL) on food packages to increase consumer attention to this resource and to promote healthier dietary choices. Aims. The present study sought to determine whether the proposed NFL changes will affect consumer attention to the NFL or purchase intentions. Method. This study compared purchase intentions (yes/no responses to “would you purchase this food?” for 64 products) and attention to NFLs (measured via high-speed eye-tracking camera) among 155 young adults randomly assigned to view products with existing versus modified NFLs. Attention to all individual components of the NFL (e.g., calories, fats, sugars) were analyzed separately to assess the impact of each proposed NFL modification on attention to that region. Data were collected in 2014; analysis was conducted in 2015. Results. Modified NFLs did not elicit significantly more visual attention or lead to more healthful purchase intentions than did existing NFLs. Relocating the percent daily value component from the right side of the NFL to the left side, as proposed by the FDA, actually reduced participants’ attention to this information. The proposed “added sugars” component was viewed on at least one label by a majority (58%) of participants. Discussion. Results suggest that the proposed NFL changes may not achieve FDA’s goals. Changes to nutrition labeling may need to take a different form to meaningfully influence dietary behavior. Conclusion. Young adults’ visual attention and purchase intentions do not appear to be meaningfully affected by the proposed NFL modifications.