Equating NHANES Monitor-Based Physical Activity to Self-Reported Methods to Enhance Ongoing Surveillance Efforts.

PURPOSE: Harmonization of assessment methods represents an ongoing challenge in physical activity research. Previous research has demonstrated the utility of calibration approaches to enhance agreement between measures of physical activity. The present study utilizes a calibration methodology to add behavioral context from the Global Physical Activity Questionnaire (GPAQ), an established report-based measure, to enhance interpretations of monitor-based data scored using the novel Monitor Independent Movement Summary (MIMS) methodology. METHODS: Matching data from the GPAQ and MIMS were obtained from adults (20-80 yr of age) assessed in the 2011-2014 National Health and Nutrition Examination Survey. After developing percentile curves for self-reported activity, a zero-inflated quantile regression model was developed to link MIMS to estimates of moderate to vigorous physical activity (MVPA) from the GPAQ. RESULTS: Cross-validation of the model showed that it closely approximated the probability of reporting MVPA across age and activity-level segments, supporting the accuracy of the zero-inflated model component. Validation of the quantile regression component directly corresponded to the 25%, 50%, and 75% values for both men and women, further supporting the model fit. CONCLUSIONS: This study offers a method of improving activity surveillance by translating accelerometer signals into interpretable behavioral measures using nationally representative data. The model provides accurate estimates of minutes of MVPA at a population level but, because of the bias and error inherent in report-based measures of physical activity, is not suitable for converting or interpreting individual-level data. This study provides an important preliminary step in utilizing information from both device- and report-based methods to triangulate activity related outcomes; however additional measurement error modeling is needed to improve precision.

Family-Based Telehealth Initiative to Improve Nutrition and Physical Activity for Children With Obesity and Its Utility During COVID-19: A Mixed Methods Evaluation.

Guidelines recommend primary care providers refer children with obesity to behavioral interventions, but given limited program availability, access, and parental engagement, referrals remain rare. We developed telehealth coaching interventions for families whose children received care at a health system in Pennsylvania, United States in 2019-2020. Intervention referrals were facilitated by the pediatrician and/or project team for 6-12-year-old children with obesity following well-child visits. Participants chose one of three 26-week interventions focused on healthy eating, physical activity, or a hybrid clinical/nutrition intervention. Interventions engaged parents as change agents, enhancing self-efficacy to model and reinforce behavior and providing resources to help create a healthy home environment. We enrolled 77 of 183 eligible parent/child dyads. We used mixed methods to evaluate the interventions. Repeated measures models among participants showed significant reductions in obesogenic nutrition behaviors post-intervention and at 1-year follow-up, including a reduction in sugar-sweetened beverage intake of 2.14 servings/week (95% confidence interval: -3.45, -0.82). There were also improvements in obesoprotective nutrition behaviors (e.g., frequency of family meals, parental self-efficacy related to meal management). One year post-baseline, we observed no significant differences in changes in body mass index (BMI) z-scores comparing child participants with matched controls. Given potential impacts of COVID-19 community restrictions on study outcomes, we conducted qualitative interviews with 13 participants during restrictions, which exemplified how disrupted routines constrained children's healthy behaviors but that intervention participation prepared parents by providing cooking and physical activities at home. Findings support the potential of a telehealth-delivered nutrition intervention to support adoption of healthy weight behaviors.

Development, Applications, and Refinement of the Family Nutrition and Physical Activity (FNPA) Child Obesity Prevention Screening.

Concerns regarding the continued high prevalence of childhood overweight and obesity have created a need for proactive approaches to behavior change. The Family Nutrition and Physical Activity (FNPA) screening tool was developed for research and clinical use to identify home environments and behaviors that could predispose youth to increased weight. FNPA scores have been shown to correlate with body mass index (BMI) percentiles in first-grade students and to predict unique variance in change in BMI percentiles from first to second grade. The FNPA has been used for family behavior counseling and is now a standard component of well-child visits throughout the Geisinger Health System in Pennsylvania. Parents complete the FNPA prior to annual visits, and providers can discuss areas of concern based on screening results. Children of parents who complete the FNPA have shown smaller increases in BMI z-scores over the following year than children of parents who did not complete the FNPA. The FNPA is also used to inform the arrangement of family-centered obesity treatment for children. Recently, the FNPA has undergone a systematic update to ensure its continued relevance and utility. The updated tool is provided, and current and future users can access more information about the tool at myfnpa.org.

Associations between physical activity, sedentary behavior, and health risk behaviors among adolescents from a city in Southern Brazil / Associações entre atividade física, comportamento sedentário e comportamentos de risco à saúde entre adolescentes de uma cidade do Sul do Brasil

This study examined the independent and combined associations of physical activity (PA) and sedentary behavior (SB) with health risk behaviors in Brazilian adolescents. Participants were 893 adolescents (454 girls) from Curitiba, Brazil. The Youth Activity Profile questionnaire evaluated PA and the Adolescent Sedentary Questionnaire evaluated SB. The Youth Risk Behavior Surveillance System ( YRBS) questionnaire evaluated fruit, vegetable, alcohol, and tobacco consumption. Binary Logistic regression measured the independent and combined associations of PA and SB with risk behaviors. PA was inversely associated with low fruit (OR = 0.30; 95%CI: 0.18-0.51) and vegetable consumption (OR = 0.43; 95%CI: 0.25-0.73), and tobacco use (OR = 0.52; 95%CI: 0.29-0.89). However, PA was positively associated with mild (OR = 1.54; 95%CI: 1.08-2.19) and excessive alcohol use (OR = 1.53; 95%CI: 1.01-2.33). Higher levels of PA were associated with reduced risks of smoking and healthier eating patterns, but higher likelihood of alcohol consumption

Este estudo examinou as associações independentes e combinadas de atividade física (AF) e do comportamento sedentário (CS) com comportamentos de risco à saúde em adolescentes brasileiros. Participaram do estudo 893 adolescentes (454 meninas) de Curitiba, Brasil. O questionário Youth Activity Profile avaliou a AF e o Questionário de atividades sedentárias dos adolescentes avaliou o CS. O questionário Youth Risk Behavior Surveillance System (YRBS) avaliou o consumo de frutas, vegetais, álcool e tabaco. A regressão logística binária avaliou as associações independentes e combinadas de AF e CS com comportamentos de risco. AF foi inversamente associado com baixo consumo de frutas (OR = 0,30; IC95%: 0,18-0,51), de vegetais (OR = 0,43; IC95%: 0,25-0,73) e uso de tabaco (OR = 0,52; IC95%: 0,29-0,89). No entanto, a AF foi positivamente associada com uso moderado (OR = 1,54; IC95%: 1,08-2,19) e uso excessivo de álcool (OR = 1,53; IC95%: 1,01-2,33). Níveis mais altos de AF foram associados com riscos reduzidos de fumar e padrões alimentares mais saudáveis e com maior probabilidade de consumo de álcool

Grip strength cutpoints for youth based on a clinically relevant bone health outcome.

The National Academy of Medicine recommends the handgrip for school-based surveillance of muscle strength for bone health. We established grip strength cutpoints that are linked to bone health in both US and European youth. These cutpoints could serve as a potential set of standards for surveillance and clinical applications. PURPOSE: The U.S. National Academy of Medicine and experts in Europe recommend the use of grip strength as a valuable and accessible musculoskeletal fitness measure due to its association with bone health. This is the first study to facilitate this recommendation by developing bone health-related grip strength cutpoints for youth based on empirical associations with the well accepted marker of bone development, i.e., height-adjusted total body less head bone mineral content (TBLH_BMC). METHODS: A purposive sample of healthy youth from Midwest USA (n = 433 youth; 14.1 ± 2.3 years; 1998-2004) and a random sample of healthy adolescents from Zaragoza, Spain (n = 355 youth; 14.9 ± 1.2 years; 2006-2007) were used to develop and test cut-points. Participants' grip strength was measured using a hand-held dynamometer while height-adjusted TBLH_BMC was determined using dual-energy x-ray absorptiometry. Grip strength scores were linked to TBLH_BMC using receiver operator characteristic curves, and grip strength cutpoints were tested based on the area under the curve (AUC), sensitivity (Se), specificity (Sp), and predictive odds ratios. All analyses were conducted in 2016. RESULTS: The AUC approximated or exceeded 0.80 for grip strength cutpoints, and the associated Se and Sp indices ranged from 53.6 to 92.5%. Sensitivity and Sp remained similar in the validation sample and those not meeting the grip strength cutpoints were five to eight times more likely to have insufficient TBLH_BMC, depending on their sex and cutpoint being considered. CONCLUSIONS: Grip strength is strongly related to TBLH_BMC, and the proposed cutpoints demonstrated acceptable classification accuracy for screening healthy youth and tracking healthy bone development in community settings. The utility of the cutpoints should be further examined in more diverse populations of youth.

The Healthy Fitness Zone Continuum Score as a Measure of Change in Body Mass Index of School-Aged Children and Adolescents, Georgia, 2012-2014.

OBJECTIVES: The FitnessGram Healthy Fitness Zone continuum (HFZc) score reflects the relative difference of a person's body mass index (BMI) from the established FitnessGram standard. As such, it may provide added utility for public health programming and research on obesity among school-aged children and adolescents. We used the standard BMI Z (BMIz) score and the alternative HFZc score to describe changes in BMI of school-aged children and adolescents in Georgia over time. METHODS: We compiled 2012-2014 BMI data from the Georgia FitnessGram database. The sample included 162 992 boys and 141 711 girls enrolled in 239 schools from a large urban district in Georgia. We analyzed trends in BMIz and HFZc scores separately for normal-weight, overweight, and obese categories for school-aged children and adolescents using hierarchical linear models. RESULTS: From 2012 to 2014, the BMIz score shifted favorably in up to 40.7% (2052/5047) of normal-weight, 51.0% (758/1485) of overweight, and 52.8% (5430/10 279) of obese students. We also found favorable shifts in HFZc score in up to 69.8% (105 831/151 739) of normal-weight, 78.3% (3605/4603) of overweight, and 80.8% (8305/10 279) of obese students. CONCLUSIONS: Compared with the BMIz score, the HFZc score may be a better indicator of favorable changes in BMI over time among school-aged children and adolescents with different baseline BMI levels, making it potentially valuable for use in individualized assessments, school programs, obesity research, and public health curriculum and policy development.

Surveillance of Youth Physical Activity and Sedentary Behavior With Wrist Accelerometry.

INTRODUCTION: Accurate tracking of physical activity (PA) and sedentary behavior (SB) is important to advance public health, but little is known about how to interpret wrist-worn accelerometer data. This study compares youth estimates of SB and moderate to vigorous PA (MVPA) obtained using raw and count-based processing methods. METHODS: Data were collected between April and October 2014 for the National Cancer Institute's Family Life, Activity, Sun, Health, and Eating Study: a cross-sectional Internet-based study of youth/family cancer prevention behaviors. A subsample of 628 adolescents (aged 12-17 years) wore the ActiGraph GT3X+ on the wrist for 7 days. In 2015-2016, SB and MVPA time were calculated from raw data using R-package GGIR and from activity counts data using published cutpoints (Crouter and Chandler). Estimates were compared across age, sex, and weight status to examine the impact of processing methods on behavioral outcomes. RESULTS: ActiGraph data were available for 408 participants. Large differences in SB and MVPA time were observed between processing methods, but age and gender patterns were similar. Younger children (aged 12-14 years) had lower sedentary time and greater MVPA time (p-values <0.05) than older children (aged 15-17 years), consistent across methods. The proportion of youth with ≥60 minutes of MVPA/day was highest with the Crouter methods (~50%) and lowest with GGIR (~0%). CONCLUSIONS: Conclusions about youth PA and SB are influenced by the wrist-worn accelerometer data processing method. Efforts to harmonize processing methods are needed to promote standardization and facilitate reporting of monitor-based PA data.

Calibration and Validation of the Youth Activity Profile: The FLASHE Study.

INTRODUCTION: This study describes the calibration and validity of the Youth Activity Profile (YAP) for use in the National Cancer Institute's Family Life, Activity, Sun, Health, and Eating (FLASHE) study. The calibrated YAP was designed to estimate minutes of moderate to vigorous physical activity (MVPA) and sedentary behavior (SB). METHODS: The YAP was calibrated/validated in adolescents (aged 12-17 years) using cross-sectional data from the FLASHE study. Participants wore a GT3X+ ActiGraph on the dominant wrist for 7 days and then completed the YAP. Calibration was conducted for school (n=118); out of school (n=119); weekend (n=61); and SB (n=116) subsections of the YAP and by regressing percentage time in MVPA/SB (%MVPA/%SB) on each respective YAP subsection score, age, and the interaction between these two. The final algorithms were applied to independent samples (n=39-51) to examine validity (median absolute percentage error, equivalence testing). RESULTS: The final algorithms explained 15% (school); 16% (out of school); and 12% (weekend) of the variability in GT3X+ %MVPA and 7% of the variability in GT3X+ %SB. The calibrated algorithms were applied to independent samples and predicted GT3X+ minutes of MVPA/SB, with median absolute percentage error values ranging from 12.5% (SB section) to 32.5% (weekend section). Predicted values obtained from the YAP were within 10%-20% of those produced by the GT3X+. CONCLUSIONS: The YAP-predicted minutes of MVPA/SB resulted in similar group estimates obtained from an objective measure. The YAP offers good utility for large-scale research projects to characterize PA/SB levels among groups of youth.

Agreement Between VO2peak Predicted From PACER and One-Mile Run Time-Equated Laps.

PURPOSE: This study examined the agreement between estimated peak oxygen consumption (VO2peak) obtained from the Progressive Aerobic Cardiovascular Endurance Run (PACER) fitness test and equated PACER laps derived from One-Mile Run time (MR). METHODS: A sample of 680 participants (324 boys and 356 girls) in Grades 7 through 12 completed both the PACER and the MR assessments. MR time was converted to PACER laps (PACER-MEQ) using previously developed conversion algorithms. Agreement between PACER and PACER-MEQ VO2peak was examined using Pearson correlations, mean absolute percent error (MAPE), and equivalence testing procedures. Classification agreement based on health-related standards was examined using sensitivity, specificity, and Kappa statistics. RESULTS: Overall agreement between estimated VO2peak obtained from the PACER and PACER-MEQ was high in boys, r(324) = .79, R2 = .63, and moderate in girls, r(356) = .57, R2 = .33. The MAPE for estimates obtained from PACER-MEQ was 10.3% and estimates were deemed equivalent to the PACER (43.1 ± 6.9 mL/kg/min vs. 44.6 ± 0.3 mL/kg/min). Classification agreement as illustrated by sensitivity and specificity ranged from 20.4% to 90.2% and was higher for classifications in the Healthy Fitness Zone (HFZ). Kappa statistics ranged from .14 to .51 and were also higher for the HFZ. CONCLUSIONS: Equated PACER laps can be used to obtain equivalent estimates of PACER VO2peak in groups of adolescents, but some disparities can be found when students' scores are classified into the Needs Improvement Zone.

Associations Between Physical Activity and Metabolic Syndrome: Comparison Between Self-Report and Accelerometry.

PURPOSE: To assess the relationship between self-reported and objectively measured physical activity (PA) and metabolic syndrome and its risk factors in U.S. adults. DESIGN: A cross-sectional design was used for this study. SETTING: The study was set among a nationally representative sample of U.S. adults. SUBJECTS: Adults, ages 20 years and older, from the National Health and Nutrition Examination Survey (NHANES) 2003-2006 (n = 5580) participated in the study. MEASURES: PA measures included minutes per week of moderate plus vigorous PA estimated by self-report (MVPAsr), total 7-day accelerometry (MVPAa), and accelerometer-based MVPA performed in 10-minute bouts (MVPAb). Risk factors for metabolic syndrome included blood pressure, high-density lipoprotein cholesterol, triglycerides, glucose, and waist circumference. ANALYSIS: Odds ratios (ORs) for having metabolic syndrome were calculated for men and women who met the Physical Activity Guidelines for Americans compared to those who did not. RESULTS: Women who did not meet the PA guidelines had significantly greater odds of having metabolic syndrome according to MVPAsr (OR = 2.20; 95% confidence interval [CI] = 1.65-2.94), MVPAa (OR = 4.40; 95% CI = 2.65-7.31), and MVPAb (OR = 2.91; 95% CI = 1.42-5.96). Men had significantly higher odds of having metabolic syndrome according to MVPAa (OR = 2.57; 95% CI = 1.91-3.45) and MVPAb (OR = 2.83; 95% CI = 1.55-5.17), but not MVPAsr. These ORs remained significant after adjusting for all potential confounders except body mass index, after which only MVPAsr in women and MVPAb in men remained significant. CONCLUSION: Individuals who do not meet the PA guidelines exhibited greater odds of having metabolic syndrome. This relationship tended to be stronger for objective PA measures than for self-report.

Adherence to physical activity guidelines in mid-pregnancy does not reduce sedentary time: an observational study.

BACKGROUND: Physical activity (PA) interventions designed to prevent prenatal complications have focused on increasing moderate PA yielding conflicting results. Minimal attention has focused on the evaluation of sleep, sedentary behavior (SB), light activity or total daily PA during pregnancy. The purpose of this prospective, longitudinal study was to 1) objectively quantify and compare habitual PA and SB during the 2nd and 3rd trimester; and 2) evaluate differences in activity patterns for women meeting prenatal PA guidelines versus those that did not. METHODS: Forty-six participants wore 2 PA monitors (SenseWear Mini and activPAL) during week 18 and week 35 of pregnancy. We compared differences in sleep duration, postural allocation, daily steps, and PA between the 2nd and 3rd trimester and for women who met and did not meet PA guidelines. RESULTS: During the 2(nd) trimester, 30% of the women's day (24-hours) was total sleep; 52% SB; 13% light; 3% moderate; and 0% vigorous PA. Light (P = 0.05), vigorous (P = 0.02), and moderate-vigorous PA (MET-minutes; P = 0.02), decreased with a trend in increased SB (P = 0.07). Activity of other intensities and sleep duration did not significantly change. Only 39% and 37% of participants slept between 7-9 hours/night at week 18 and 35, respectively. Forty-six percent (n = 21) and 28% (n = 13) of participants met prenatal PA guidelines during the 2(nd) and 3(rd) trimester, respectively. At week 18, no differences in total sleep, SB, or light PA existed for women who met PA guidelines versus those who did not; total PA was significantly greater for women who met guidelines. At week 35, women that met PA guidelines had significantly less SB (P < 0.005) than women who did not. CONCLUSIONS: This study demonstrates that pregnant women spend the majority of their day in SB. Significant reductions in total activity across pregnancy may be attributed, in part to shifts in light PA and increased SB. Based on the lifestyle of our sample, regardless of meeting PA guidelines in mid-pregnancy, no significant difference exists in time spent in SB, however meeting PA recommendations in late pregnancy may reduce SB. Future interventions should target reducing SB by increasing light and moderate PA beyond volitional exercise.

Validity of physical activity monitors for assessing lower intensity activity in adults.

BACKGROUND: Accelerometers can provide accurate estimates of moderate-to-vigorous physical activity (MVPA). However, one of the limitations of these instruments is the inability to capture light activity within an acceptable range of error. The purpose of the present study was to determine the validity of different activity monitors for estimating energy expenditure (EE) of light intensity, semi-structured activities. METHODS: Forty healthy participants wore a SenseWear Pro3 Armband (SWA, v.6.1), the SenseWear Mini, the Actiheart, ActiGraph, and ActivPAL monitors, while being monitored with a portable indirect calorimetry (IC). Participants engaged in a variety of low intensity activities but no formalized scripts or protocols were used during these periods. RESULTS: The Mini and SWA overestimated total EE on average by 1.0% and 4.0%, respectively, while the AH, the GT3X, and the AP underestimated total EE on average by 7.8%, 25.5%, and 22.2%, respectively. The pattern-recognition monitors yielded non-significant differences in EE estimates during the semi-structured period (p = 0.66, p = 0.27, and p = 0.21 for the Mini, SWA, and AH, respectively). CONCLUSIONS: The SenseWear Mini provided more accurate estimates of EE during light to moderate intensity semi-structured activities compared to other activity monitors. This monitor should be considered when there is interest in tracking low intensity activities in groups of individuals.

Body Mass Index standards based on agreement with health-related body fat.

BACKGROUND: Multiple screening tools, such as BMI and skinfold-derived percent body fat (%BF), are available to identify youth at risk of excess adiposity. However, poor classification agreement among these tools can be problematic for those interpreting test results. PURPOSE: The purpose of this study was to investigate the validity of using BMI as an estimate of %BF in youth and to identify optimal BMI thresholds for identifying at-risk children and adolescents based on %BF. METHODS: Percent body fat was derived from the skinfold thicknesses of children aged 5-18 years from three cross-sectional waves of the National Health and Nutrition Examination Survey (NHANES [1999-2004]; N=8269). Stature and body mass from the same data set were used to calculate BMI. Receiver operating characteristic (ROC) analysis was employed to determine the optimal BMI thresholds for detecting previously created %BF standards. RESULTS: The optimal BMI percentile associated with the low risk %BF threshold was the 83 rd and 80th in boys and girls, respectively. The selected BMI percentiles associated with the higher risk threshold were the 92 nd and 90th in boys and girls, respectively. Overall, classification accuracy when using BMI percentiles to identify the two %BF risk groups ranged from 86.9% to 89.1%. CONCLUSIONS: BMI and skinfold-derived %BF demonstrate reasonable agreement when used to classify adiposity status in children and adolescents.

Validity of the Bouchard activity diary in Spanish adolescents.

OBJECTIVE: Valid and simple instruments to assess physical activity (PA) in specific populations are required for health-related research. The aim of the present study was to assess the validity of the Bouchard activity diary (AD) in Spanish adolescents using an activity monitor to compare total PA and moderate-to-vigorous PA (MVPA) obtained by both instruments. DESIGN: Sixty-one Spanish adolescents, aged 12-16 years, completed the Bouchard AD and wore the ActiGraph activity monitor for three consecutive days. Validity was assessed with the Spearman correlation coefficient (rho), the Bland-Altman method and the kappa coefficient. RESULTS: Thirty-seven adolescents were included in the final analysis. Correlations between the activity monitor and the AD administered over the three days (Thursday-Saturday) were moderate (rho = 0.33-0.35, P < 0.05) or non-significant for total PA and moderate (rho = 0.36, P < 0.05) for MVPA. Correlations between the two methods were progressively lower for each subsequent day of testing, for both total PA and MVPA. The Bland-Altman plot illustrated that the Bouchard AD overestimated MVPA (mean difference -32.05 (sd 74.56) min; 95 % limits of agreement 109.61, -173.31 min). Agreements for classification into MVPA tertiles and accordance with the international recommendations of MVPA were fair and moderate, respectively, for the 3 d means. CONCLUSIONS: The Bouchard AD has reasonable validity to assess total PA and MVPA in Spanish adolescents. The results show lower levels of agreement on the third day but it is not clear if this is due to design features (weekday v. weekend) or to participant compliance with the survey or the activity monitoring protocol.

Prediction of BMI change in young children with the family nutrition and physical activity (FNPA) screening tool.

BACKGROUND: Youth obesity prevention practices would be enhanced if modifiable risk factors can be identified before children become overweight. PURPOSE: This study evaluated the predictive validity of the Family Nutrition and Physical Activity (FNPA) screening tool, a behaviorally based screening tool designed to assess family environments and behaviors that may predispose youth to becoming overweight. METHODS: Parents from a large urban school district completed the FNPA screening when children were in first grade. One-year change in measured body mass index (BMI) was used as the primary outcome, and this was computed using the relative change in distance from the BMI value at the 50th percentile. Descriptive, correlation, and mixed modeling analyses were used for survey validation. RESULTS: Over half of the participants exhibited an increase in BMI percentile over the 1-year follow-up with an average change of 0.51 +/- 11.5% which is indicative of trends to overweight. Although baseline BMI predicted BMI at follow-up, the FNPA total score explained unique variance in child BMI at follow-up after accounting for baseline BMI, parent BMI, and other demographic variables (p = 0.049). CONCLUSIONS: This study demonstrates the potential validity of a simple, easy-to-use screening tool for identifying children that may be at risk for becoming overweight.

Associations between sedentary behavior and blood pressure in young children.

OBJECTIVE: To examine the effect of sedentary behavior on blood pressure (BP) in young children using different indicators of sedentariness. DESIGN: Cross-sectional study. SETTING: A rural Midwestern US community. PARTICIPANTS: Children aged 3 to 8 years (N = 111). Intervention Adiposity was assessed using dual energy x-ray absorptiometry. Objective measurements of sedentary activity were obtained from the accelerometers that participants wore continuously for 7 days. Measurements of television (TV) viewing, computer, and screen time (TV + computer) were obtained via parent report. MAIN OUTCOME MEASURES: Systolic and diastolic BP. RESULTS: The sample spent a mean of 5 hours per day in sedentary activities, of which 1.5 hours were screen time. Accelerometer-determined sedentary activity was not significantly related to systolic BP or diastolic BP after controlling for age, sex, height, and percentage of body fat. However, TV viewing and screen time, but not computer use, were positively associated with both systolic BP and diastolic BP after adjusting for potential confounders. Participants in the lowest tertile of TV and screen time had significantly lower levels of systolic and diastolic BP than participants in the upper tertile. CONCLUSIONS: Sedentary behaviors, particularly TV viewing and screen time, were associated with BP in children, independent of body composition. Other factors that occur during excessive screen time (eg, food consumption) should also be considered in the context of sedentary behavior and BP development in children.

SWITCH: rationale, design, and implementation of a community, school, and family-based intervention to modify behaviors related to childhood obesity.

BACKGROUND: Although several previous projects have attempted to address the issue of child obesity through school-based interventions, the overall effectiveness of school-based programs on health-related outcomes in youth has been poor. Thus, it has been suggested that multi-level interventions that aim to influence healthy lifestyle behaviors at the community, school and family levels may prove more successful in the prevention of childhood obesity. METHODS/DESIGN: This paper describes the rationale, design, and implementation of a community-, school-, and family-based intervention aimed at modifying key behaviors (physical activity, screen time (Internet, television, video games), and nutrition) related to childhood obesity among third through fifth graders in two mid-western cities. The intervention involves a randomized study of 10 schools (5 intervention and 5 control schools). The intervention is being conducted during the duration of the academic year - approximately 9 months - and includes baseline and post-intervention measurements of physical activity, dietary intake, screen time and body composition. DISCUSSION: We hope this report will be useful to researchers, public health professionals, and school administrators and health professionals (nurses and physical/health educators) seeking to develop similar prevention programs. It is obvious that more collaborative, inter-disciplinary, multi-level work is needed before a proven, effective intervention package to modify behaviors related to childhood obesity can be generally recommended. It is our hope that SWITCH is a step in that direction. TRIAL REGISTRATION: ClinicalTrials.gov NCT00685555.

Differences in daily energy expenditure in lean and obese women: the role of posture allocation.

OBJECTIVE: A low resting metabolic rate (RMR) is considered a risk factor for weight gain and obesity; however, due to the greater fat-free mass (FFM) found in obesity, detecting an impairment in RMR is difficult. The purposes of this study were to determine the RMR in lean and obese women controlling for FFM and investigate activity energy expenditure (AEE) and daily activity patterns in the two groups. METHODS AND PROCEDURES: Twenty healthy, non-smoking, pre-menopausal women (10 lean and 10 obese) participated in this 14-day observational study on free-living energy balance. RMR was measured by indirect calorimetry; AEE and total energy expenditure (TEE) were calculated using doubly labeled water (DLW), and activity patterns were investigated using monitors. Body composition including FFM and fat mass (FM) was measured by dual energy X-ray absorptiometry (DXA). RESULTS: RMR was similar in the obese vs. lean women (1601 +/- 109 vs. 1505 +/- 109 kcal/day, respectively, P = 0.12, adjusting for FFM and FM). Obese women sat 2.5 h more each day (12.7 +/- 3.2 h vs. 10.1 +/- 2.0 h, P < 0.05), stood 2 h less (2.7 +/- 1.0 h vs. 4.7 +/- 2.2 h, P = 0.02) and spent half as much time in activity than lean women (2.6 +/- 1.5 h vs. 5.4 +/- 1.9 h, P = 0.002). DISCUSSION: RMR was not lower in the obese women; however, they were more sedentary and expended less energy in activity than the lean women. If the obese women adopted the activity patterns of the lean women, including a modification of posture allocation, an additional 300 kcal could be expended every day.