Motor unit firing rates increase in prepubescent youth following linear periodization resistance exercise training.

PURPOSE: The purpose was to examine the effects of 8-weeks (3 days/week) of linear periodization resistance exercise training (RET) on neuromuscular function in prepubescent youth. METHODS: Twenty-five healthy prepubescent youth (11 males, 14 females, age = 9.1 ± 0.8 years) completed the RET (n = 17) or served as controls (CON, n = 8). Isometric maximal voluntary contractions (MVCs) and trapezoidal submaximal contractions at 35 and 60% MVC of the right leg extensors were performed with surface electromyography (EMG) recorded from the leg extensors [vastus lateralis (VL), rectus femoris, and vastus medialis] and flexors (biceps femoris and semitendinosus). EMG amplitude of the leg extensors and flexors were calculated during the MVCs. Motor unit (MU) action potential trains were decomposed from the surface EMG of the VL for the 35 and 60% MVCs. MU firing rates and action potential amplitudes were regressed against recruitment threshold with the y-intercepts and slopes calculated for each contraction. Total leg extensor muscle cross-sectional area (CSA) was collected using ultrasound images. ANOVA models were used to examine potential differences. RESULTS: Isometric strength increased post-RET (P = 0.006) with no changes in leg extensor and flexor EMG amplitude. Furthermore, there were no changes in total CSA or the MU action potential amplitude vs. recruitment threshold relationships. However, there were increases in the firing rates of the higher-threshold MUs post-RET as indicated with greater y-intercepts (P = 0.003) from the 60% MVC and less negative slope (P = 0.004) of the firing rates vs. recruitment threshold relationships at 35% MVC. CONCLUSIONS: MU adaptations contribute to strength increases following RET in prepubescent youth.

Association between frailty and sleep quality in people living with multiple sclerosis and obesity: An observational cross-sectional study.

BACKGROUND: A majority of the people with multiple sclerosis (pwMS) experience sleep disturbances. Frailty is also common in pwMS. The geriatric literature strongly suggests that frailty is associated with worse sleep outcomes in community-dwelling older adults, but this association has yet to be explored among pwMS. This study focused on examining the association between frailty and sleep quality in pwMS. METHODS: Seventy-six people with both MS and obesity (mean age: 47.6 ± 10.9 years, 81.6 % female, mean body mass index (BMI): 37.10 ± 5.5 kg/m2, mean Patient Determined Disease Steps (PDDS): 0.82 ± 1.20) were included in this cross-sectional secondary analysis. A comprehensive frailty index (FI) based on 41 health deficits from various health domains was calculated based on standardized procedures. Sleep quality was determined by the Pittsburgh Sleep Quality Index questionnaire (PSQI). RESULTS: Overall, 67.1 % of the participants were identified as non-frail (FI ≤ 0.25), and 32.9 % were identified as frail (FI > 0.25). A significant correlation was observed between FI scores and global PSQI scores (ρ = 0.43, p < 0.05). Cross-tabulation analyses revealed that frail participants had worse subjective sleep quality, sleep latency, habitual sleep efficiency, sleep disturbances, daytime dysfunction, and higher use of sleep medications compared to non-frail participants (p < 0.05). CONCLUSIONS: The current study identified a significant association between frailty and sleep quality in people with both MS and obesity with minimal disability. These findings underscore the importance of untangling the relationship between frailty and sleep quality in pwMS. These results could lead to a more targeted approach for rehabilitation interventions aiming to improve frailty in MS.

Modifying diet and exercise in multiple sclerosis (MoDEMS): A randomized controlled trial for behavioral weight loss in adults with multiple sclerosis and obesity.

BACKGROUND: Obesity is a risk factor for developing multiple sclerosis (MS) and MS-related disability. The efficacy of behavioral weight loss interventions among people with MS (pwMS) remains largely unknown. OBJECTIVE: Examine whether a group-based telehealth weight loss intervention produces clinically significant weight loss in pwMS and obesity. METHODS: Seventy-one pwMS were randomized to the weight loss intervention or treatment-as-usual (TAU). The 6-month program promoted established guidelines for calorie reduction and increased physical activity. Anthropometric measurements, mobility tasks, self-report questionnaires, and accelerometry were used to assess changes at follow-up. RESULTS: Mean percent weight loss in the treatment group was 8.6% compared to 0.7% in the TAU group (p < .001). Sixty-five percent of participants in the intervention achieved clinically meaningful weight loss (⩾ 5%). Participants in the treatment group engaged in 46.2 minutes/week more moderate-to-vigorous physical activity than TAU participants (p = .017) and showed improvements in quality of life (p = .012). Weight loss was associated with improved mobility (p = .003) and reduced fatiguability (p = .008). CONCLUSION: Findings demonstrate the efficacy of a behavioral intervention for pwMS and obesity, with clinically significant weight loss for two-thirds of participants in the treatment condition. Weight loss may also lead to improved mobility and quality of life.

A pilot study evaluating the prefeasibility of a behavioral weight loss program in people with multiple sclerosis.

Weight loss interventions seldom include individuals with neurologic disease. The aims of the present study were to: 1) develop and assess the prefeasibility of a 6-month telehealth behavioral weight loss program for people with multiple sclerosis (MS) and obesity and 2) examine changes in weight loss (primary outcome), physical activity, and fruit/vegetable consumption at follow-up. Participants with obesity and MS engaged in a 24-week weight loss program. Participants followed established diet, exercise, and self-monitoring guidelines and attended weekly online group meetings. Median percentage weight loss was 10.54 % (SD = 7.19). Participants who adhered more closely to the self-monitoring guidelines (r = 0.81, p =.02), and who averaged higher weekly active minutes (r = 0.91, p =.002) achieved greater percentage weight loss. Six of the eight pilot participants achieved clinically meaningful weight loss (>5%) after 6-months.

Criterion validity of wrist accelerometry for assessing energy intake via the intake-balance technique.

BACKGROUND: Intake-balance assessments measure energy intake (EI) by summing energy expenditure (EE) with concurrent change in energy storage (ΔES). Prior work has not examined the validity of such calculations when EE is estimated via open-source techniques for research-grade accelerometry devices. The purpose of this study was to test the criterion validity of accelerometry-based intake-balance methods for a wrist-worn ActiGraph device. METHODS: Healthy adults (n = 24) completed two 14-day measurement periods while wearing an ActiGraph accelerometer on the non-dominant wrist. During each period, criterion values of EI were determined based on ΔES measured by dual X-ray absorptiometry and EE measured by doubly labeled water. A total of 11 prediction methods were tested, 8 derived from the accelerometer and 3 from non-accelerometry methods (e.g., diet recall; included for comparison). Group-level validity was assessed through mean bias, while individual-level validity was assessed through mean absolute error, mean absolute percentage error, and Bland-Altman analysis. RESULTS: Mean bias for the three best accelerometry-based methods ranged from -167 to 124 kcal/day, versus -104 to 134 kcal/day for the non-accelerometry-based methods. The same three accelerometry-based methods had mean absolute error of 323-362 kcal/day and mean absolute percentage error of 18.1-19.3%, versus 353-464 kcal/day and 19.5-24.4% for the non-accelerometry-based methods. All 11 methods demonstrated systematic bias in the Bland-Altman analysis. CONCLUSIONS: Accelerometry-based intake-balance methods have promise for advancing EI assessment, but ongoing refinement is necessary. We provide an R package to facilitate implementation and refinement of accelerometry-based methods in future research (see paulhibbing.com/IntakeBalance).

Neighborhood park access and park characteristics are associated with weight status in youth.

This study investigated park access and park quality in the context of childhood obesity. Participants were 20,638 children ages 6-17y from a large primary care health system. Analyses tested associations of park access and park characteristics with children's weight status, and sociodemographic interactions. Both park access and the quality of nearest park were associated with a lower odds of having obesity. Park quality interacted with age, sex, and income. Findings suggest park access is important for supporting a healthy weight in children. Park quality may be most important among 12-14-year-olds, girls, and higher income groups.

Neurocomputational mechanisms of food and physical activity decision-making in male adolescents.

We examined the neurocomputational mechanisms in which male adolescents make food and physical activity decisions and how those processes are influenced by body weight and physical activity levels. After physical activity and dietary assessments, thirty-eight males ages 14-18 completed the behavioral rating and fMRI decision tasks for food and physical activity items. The food and physical activity self-control decisions were significantly correlated with each other. In both, taste- or enjoyment-oriented processes were negatively associated with successful self-control decisions, while health-oriented processes were positively associated. The correlation between taste/enjoyment and healthy attribute ratings predicted actual laboratory food intake and physical activities (2-week activity monitoring). fMRI data showed the decision values of both food and activity are encoded in the ventromedial prefrontal cortex, suggesting both decisions share common reward value-related circuits at the time of choice. Compared to the group with overweight/obese, the group with normal weight showed stronger brain activations in the cognitive control, multisensory integration, and motor control regions during physical activity decisions. For both food and physical activity, self-controlled decisions utilize similar computational and neurobiological mechanisms, which may provide insights into how to promote healthy food and physical activity decisions.

Associations between the Dietary Inflammatory Index and Sleep Metrics in the Energy Balance Study (EBS).

(1) Background: Sleep, a physiological necessity, has strong inflammatory underpinnings. Diet is a strong moderator of systemic inflammation. This study explored the associations between the Dietary Inflammatory Index (DII®) and sleep duration, timing, and quality from the Energy Balance Study (EBS). (2) Methods: The EBS (n = 427) prospectively explored energy intake, expenditure, and body composition. Sleep was measured using BodyMedia's SenseWear® armband. DII scores were calculated from three unannounced dietary recalls (baseline, 1-, 2-, and 3-years). The DII was analyzed continuously and categorically (very anti-, moderately anti-, neutral, and pro-inflammatory). Linear mixed-effects models estimated the DII score impact on sleep parameters. (3) Results: Compared with the very anti-inflammatory category, the pro-inflammatory category was more likely to be female (58% vs. 39%, p = 0.02) and African American (27% vs. 3%, p < 0.01). For every one-unit increase in the change in DII score (i.e., diets became more pro-inflammatory), wake-after-sleep-onset (WASO) increased (ßChange = 1.00, p = 0.01), sleep efficiency decreased (ßChange = −0.16, p < 0.05), and bedtime (ßChange = 1.86, p = 0.04) and waketime became later (ßChange = 1.90, p < 0.05). Associations between bedtime and the DII were stronger among African Americans (ßChange = 6.05, p < 0.01) than European Americans (ßChange = 0.52, p = 0.64). (4) Conclusions: Future studies should address worsening sleep quality from inflammatory diets, leading to negative health outcomes, and explore potential demographic differences.

Predicting energy intake with an accelerometer-based intake-balance method.

Nutritional interventions often rely on subjective assessments of energy intake (EI), but these are susceptible to measurement error. To introduce an accelerometer-based intake-balance method for assessing EI using data from a time-restricted eating (TRE) trial. Nineteen participants with overweight/obesity (25-63 years old; 16 females) completed a 12-week intervention (NCT03129581) in a control group (unrestricted feeding; n 8) or TRE group (n 11). At the start and end of the intervention, body composition was assessed by dual-energy X-ray absorptiometry (DXA) and daily energy expenditure (EE) was assessed for 2 weeks via wrist-worn accelerometer. EI was back-calculated as the sum of net energy storage (from DXA) and EE (from accelerometer). Accelerometer-derived EI estimates were compared against estimates from the body weight planner of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Mean EI for the control group declined by 138 and 435 kJ/day for the accelerometer and NIDDK methods, respectively (both P ≥ 0·38), v. 1255 and 1469 kJ/day, respectively, for the TRE group (both P < 0·01). At follow-up, the accelerometer and NIDDK methods showed excellent group-level agreement (mean bias of -297 kJ/day across arms; standard error of estimate 1054 kJ/day) but high variability at the individual level (limits of agreement from -2414 to +1824 kJ/day). The accelerometer-based intake-balance method showed plausible sensitivity to change, and EI estimates were biologically and behaviourally plausible. The method may be a viable alternative to self-report EI measures. Future studies should assess criterion validity using doubly labelled water.

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.

Decreased Physical Activity Among Youth Resulting From COVID-19 Pandemic-Related School Closures: Natural Experimental Study.

BACKGROUND: The COVID-19 pandemic has resulted in the closure of schools and may have inadvertently resulted in decreased physical activity for youth. Emerging evidence suggests that school closures due to the COVID-19 pandemic could have hastened the inactivity of youth, possibly due to a lack of structure outside of school and increased access to sedentary activities. OBJECTIVE: The purpose of this study was to assess changes in physical activity from pre-school closure (before the pandemic) to post-school closure (during the pandemic) among youth in spring 2020. METHODS: This study used a natural experimental design; youth were enrolled in a physical activity study prior to the lockdown, which was enforced due to the pandemic. The number of device-assessed steps per day and moderate-to-vigorous physical activity minutes per week were measured by using a Garmin Vivofit 4 (Garmin Ltd) accelerometer over 8 weeks. Mixed effects models were used to compare physical activity variables, which were measured before and during the COVID-19 pandemic. RESULTS: Youth were primarily Hispanic or Latinx (8/17, 47%) and female (10/17, 59%). The number of daily steps decreased by 45.4% during the school closure, from a pre-school closure mean of 8003 steps per day to a post-school closure mean of 4366 steps per day. Daily moderate-to-vigorous physical activity decreased by 42.5%, from a pre-school closure mean of 80.18 minutes per week to a post-school closure mean of 46.13 minutes per week. CONCLUSIONS: Youth are engaging in roughly half as much physical activity during the school closure as they were prior to the school closure. If additional evidence supports these claims, interventions are needed to support youths' engagement in physical activity in the Midwest.

Commercial Devices Provide Estimates of Energy Balance with Varying Degrees of Validity in Free-Living Adults.

BACKGROUND: The challenges of accurate estimation of energy intake (EI) are well-documented, with self-reported values 12%-20% below expected values. New approaches rely on gold-standard assessments of the other components of energy balance, energy expenditure (EE) and energy storage (ES), to estimate EI. OBJECTIVES: The purpose of this study was to evaluate the validity, repeatability, and measurement error of consumer devices when estimating energy balance in a free-living population. METHODS: Twenty-four healthy adults (14 women, 10 men; mean ± SD age: 30.7 ± 8.2 y) completed two 14-d assessment periods, including assessments of EE and ES using gold-standard [doubly labeled water (DLW) and DXA] and commercial devices [Fitbit Alta HR activity monitor (Alta) and Fitbit Aria wireless body composition scale (Aria)], and of EI by dietician-administered recalls. Accuracy and validity were assessed using Spearman correlation, interclass correlation, mean absolute percentage error, and equivalency testing. We also applied linear measurement error modeling including error in gold-standard devices and within-subject repeated-measures design to calibrate consumer devices and quantify error. RESULTS: There was moderate to strong agreement for EE between the Fitbit Alta and DLW at each time point (rs = 0.82 and 0.66 for Times 1 and 2, respectively). There was weak agreement for ES between the Fitbit Aria and DXA (rs = 0.15 and 0.49 for Times 1 and 2, respectively). Correlations between methods to assess EI ranged from weak to strong, with agreement between the DXA/DLW-calculated EI and dietary recalls being the highest (rs = 0.63 for Time 1 and 0.73 for Time 2). Only EE from the Fitbit Alta at Time 1 was equivalent to the DLW value using equivalency testing. CONCLUSIONS: Commercial devices provide estimates of energy balance in free-living adults with varying degrees of validity compared to gold-standard techniques. EE estimates were the most robust overall, whereas ES estimates were generally poor.

Perspective: Opportunities and Challenges of Technology Tools in Dietary and Activity Assessment: Bridging Stakeholder Viewpoints.

The science and tools of measuring energy intake and output in humans have rapidly advanced in the last decade. Engineered devices such as wearables and sensors, software applications, and Web-based tools are now ubiquitous in both research and consumer environments. The assessment of energy expenditure in particular has progressed from reliance on self-report instruments to advanced technologies requiring collaboration across multiple disciplines, from optics to accelerometry. In contrast, assessing energy intake still heavily relies on self-report mechanisms. Although these tools have improved, moving from paper-based to online reporting, considerable room for refinement remains in existing tools, and great opportunities exist for novel, transformational tools, including those using spectroscopy and chemo-sensing. This report reviews the state of the science, and the opportunities and challenges in existing and emerging technologies, from the perspectives of 3 key stakeholders: researchers, users, and developers. Each stakeholder approaches these tools with unique requirements: researchers are concerned with validity, accuracy, data detail and abundance, and ethical use; users with ease of use and privacy; and developers with high adherence and utilization, intellectual property, licensing rights, and monetization. Cross-cutting concerns include frequent updating and integration of the food and nutrient databases on which assessments rely, improving accessibility and reducing disparities in use, and maintaining reliable technical assistance. These contextual challenges are discussed in terms of opportunities and further steps in the direction of personalized health.

Designing an Adaptive Adolescent Physical Activity and Nutrition Intervention for COVID-19-Related Health Challenges: Formative Research Study.

BACKGROUND: With rates of childhood obesity continually increasing, effective physical activity and nutrition interventions are needed. Formative research is used to tailor interventions to different cultural and geographic contexts and can be vital in adapting intervention strategies in the face of significant disruptive circumstances (like COVID-19). OBJECTIVE: We conducted formative research via in-person and web-based focus groups among middle schoolers and parents to better understand the facilitators and barriers to physical activity and fruit and vegetable consumption and to inform the design of a large intervention for a low-income, urban setting in the US Midwest. METHODS: We conducted 2 phases of qualitative focus groups with parents (n=20) and 6th-9th grade middle schoolers (n=23). Phase 1 was conducted prior to the COVID-19 pandemic in late 2019, and phase 2 was conducted during the COVID-19 pandemic in the summer of 2020. Focus groups were transcribed and thematically coded using the Dedoose software. RESULTS: The main facilitators of physical activity prior to the pandemic included the opportunity to have fun, peer influence, competition (for some), and incentives, while the main barriers to physical activity were time constraints and social discomfort. The main facilitators of eating fruits and vegetables included parental influence, preparation technique, and convenience, while barriers included dislike of vegetables, time constraints, and preparation or freshness. During the pandemic, facilitators of physical activity remained the same, while additional barriers to physical activity such as lack of motivation and limited time spent outside of the home were reported. For fruit and vegetable consumption, both facilitators and barriers remained the same for both time periods. Additionally, for some participants, the pandemic offered an opportunity to offer more fruits and vegetables to middle schoolers throughout the day. CONCLUSIONS: Some themes identified were common to those reported in previous studies, such as peer influence on physical activity and parental influence on fruit and vegetable consumption. Novel themes such as lack of motivation to be active and limited time outside the home helped improve intervention adaptation, specifically during the COVID-19 pandemic. The continuity of formative research after a major unexpected change in the intervention context can be essential in targeting areas of an intervention that can be retained and those that need to be adjusted.

Modifying Diet and Exercise in MS (MoDEMS): Study design and protocol for a telehealth weight loss intervention for adults with obesity & Multiple Sclerosis.

Weight loss improves overall health, and reduces inflammation, risk of stroke, heart attack, diabetes, certain cancers, and death among individuals with obesity. Weight loss also improves mobility, increases stamina, and elevates mood. Between 25 and 33% of people with Multiple Sclerosis (pwMS) have obesity. Multiple Sclerosis (MS) and obesity are independently associated with reduced mobility, increased fatigue, and depression. Most behavioral weight loss trials exclude individuals with neurologic disease. Consequently, few studies have examined the effects of weight loss on symptom presentation and health outcomes among pwMS and obesity. This is the first study examining the efficacy of a comprehensive behavioral weight loss intervention designed specifically for pwMS. The purpose of this study is to develop and assess the efficacy of a telehealth administered weight loss intervention tailored for pwMS. Additionally, we aim to determine if weight loss reduces physical and emotional symptoms in individuals with obesity and MS. We will enroll 70 pwMS in a wait-list crossover trial to examine the efficacy of our intervention. If successful, findings will help determine whether we can help participants lose clinically significant weight - and whether weight loss among pwMS and overweight/obesity reduces fatigue, and improves mobility, mood, and quality of life.

Characterization of a Regional Childhood Obesity Prevention and Treatment System.

This project characterized the system of childhood obesity-related programs and functions based on a socioecological framework within the Kansas City region to determine strengths, weaknesses, and leverage points for informing collective impact. A mixed-method approach was employed to identify and collect data ∼260 childhood obesity-related programs provided by 89 organizations. Findings indicated no major gaps in population or location served although few programs specifically focused on service to minority groups or neighborhoods. The region has many programs working within the system, yet the distribution of programs does not occur as expected throughout the dimensions of a standard socioecological model or community health system. In addition, several organizations perform certain leadership functions such as coordination, resource allocation, or monitoring, but none perform all, indicating the lack of a traditional "backbone" organization. These findings demonstrate how a region's childhood obesity prevention and treatment programs can be evaluated using a socioecological framework.

Investigating associations between physical activity-related neighborhood built environment features and child weight status to inform local practice.

Despite evidence of the importance of neighborhood built environment features in relation to physical activity and obesity, research has been limited in informing localized practice due to small sample sizes and limited geographic coverage. This demonstration study integrated data from a local pediatric health system with nationally available neighborhood built environment data to inform local decision making around neighborhood environments and childhood obesity. Height/weight from clinic visits and home neighborhood measures from the U.S. Environmental Protections Agency and WalkScore were obtained for 15,989 6-17 year olds. Multilevel models accounted for the nested data structure and were adjusted for neighborhood income and child sociodemographics. In 9-17 year olds, greater street connectivity and walkability were associated with a 0.01-0.04 lower BMIz (Ps = .009-.017) and greater residential density, street connectivity, and walkability were associated 5-7% lower odds of being overweight/obese (Ps = .004-.044) per standard deviation increase in environment variable. 45.9% of children in the lowest walkability tertile were overweight or obese, whereas 43.1% of children in the highest walkability tertile were overweight or obese. Maps revealed areas with low walkability and a high income-adjusted percent of children overweight/obese. In the Kansas City area, data showed that fewer children were overweight/obese in more walkable neighborhoods. Integrating electronic health records with neighborhood environment data is a replicable process that can inform local practice by highlighting the importance of neighborhood environment features locally and pointing to areas most in need of interventions.

Beyond clinical food prescriptions and mobile markets: parent views on the role of a healthcare institution in increasing healthy eating in food insecure families.

BACKGROUND: Children in food-insecure families face increased barriers to meeting recommendations for fruit and vegetable consumption. Hospitals and pediatric healthcare institutions have attempted to alleviate food-insecurity through various internal programs like food prescriptions, yet little evidence for these programs exist. Consistent with a patient-centered perspective, we sought to develop a comprehensive understanding of barriers to fruit and vegetable consumption and a parent-driven agenda for healthcare system action. METHODS: We conducted six qualitative focus group discussions (four in English, two in Spanish) with 29 parents and caregivers of patients who had screened positive for food-insecurity during visits to a large pediatric healthcare system in a midwestern U.S. city. Our iterative analysis process consisted of audio-recording, transcribing and coding discussions, aiming to produce a) a conceptual framework of barriers to fruit and vegetable consumption and b) a synthesis of participant programmatic suggestions for their healthcare system. RESULTS: Participants were 90% female, 38% Black/African American and 41% Hispanic/Latino. Barriers to fruit and vegetable consumption in their families fell into three intersecting themes: affordability, accessibility and desirability. Participant-generated intervention recommendations were multilevel, suggesting healthcare systems focus not only on clinic and community-based action, but also advocacy for broader policies that alleviate barriers to acquiring healthy foods. CONCLUSION: Parents envision an expanded role for healthcare systems in ensuring their children benefit from a healthy diet. Findings offer critical insight on why clinic-driven programs aimed to address healthy eating may have failed and healthcare organizations may more effectively intervene by adopting a multilevel strategy.

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.

Difference in Housing Temperature-Induced Energy Expenditure Elicits Sex-Specific Diet-Induced Metabolic Adaptations in Mice.

OBJECTIVE: The aim of this study was to test whether increased energy expenditure (EE), independent of physical activity, reduces acute diet-induced weight gain through tighter coupling of energy intake to energy demand and enhanced metabolic adaptations. METHODS: Indirect calorimetry and quantitative magnetic resonance imaging were used to assess energy metabolism and body composition during 7-day high-fat/high-sucrose (HFHS) feeding in male and female mice housed at divergent temperatures (20°C vs. 30°C). RESULTS: As previously observed, 30°C housing resulted in lower total EE and energy intake compared with 20°C mice regardless of sex. Interestingly, housing temperature did not impact HFHS-induced weight gain in females, whereas 30°C male mice gained more weight than 20°C males. Energy intake coupling to EE during HFHS feeding was greater in 20°C versus 30°C housing, with females greater at both temperatures. Fat mass gain was greater in 30°C mice compared with 20°C mice, whereas females gained less fat mass than males. Strikingly, female 20°C mice gained considerably more fat-free mass than 30°C mice. Reduced fat mass gain was associated with greater metabolic flexibility to HFHS, whereas fat-free mass gain was associated with diet-induced adaptive thermogenesis. CONCLUSIONS: These data reveal that EE and sex interact to impact energy homeostasis and metabolic adaptation to acute HFHS feeding, altering weight gain and body composition change.