Objectively measured sedentary behavior,physical activity,and plasma lipids in overweight and obese children

Objective:

This study examines the associations between objectively measured sedentary behavior, light physical activity (LPA), and moderate‐to‐vigorous physical activity (MVPA), and plasma lipids in overweight and obese children.

Design and Methods:

Cross‐sectional analyses were conducted among 126 children aged 5.5‐9.9 years. Sedentary behavior, LPA, and MVPA were assessed using accelerometry. Fasting blood samples were analyzed for plasma lipids (high‐density lipoprotein cholesterol [HDL‐C], low‐density lipoprotein cholesterol [LDL‐C], total cholesterol [TC], and triglycerides [TG]).

Results:

MVPA was not related to plasma lipids (P > 0.05). Independent of age, sex, energy intake, and waist circumference z‐score, sedentary behavior and LPA were associated with HDL‐C (β = ?0.23, 95% CI ?0.42 to ?0.04, P = 0.020; β = 0.20, 95% CI 0.14 to 0.39, P = 0.036, respectively). The strength of the associations remained after additionally adjusting for MVPA (sedentary behavior: β = ?0.22, 95% CI ?0.44 to 0.006, P = 0.056; LPA: β = 0.19, 95% CI ?0.005 to 0.38, P = 0.056, respectively).

Conclusion:

Substituting at least LPA for sedentary time may contribute to the development of healthy HDL‐C levels among overweight and obese children, independent of their adiposity. Comprehensive prevention and treatment strategies to improve plasma HDL‐C among overweight and obese children should target reductions in total sedentary time and promote the benefits of LPA, in addition to promoting healthy levels of adiposity, healthy dietary behaviors, and MVPA.

     

Correlates of objectively measured physical activity in obese children

The aim of this study was to identify potential correlates of objectively measured physical activity in a sample of obese children. A cross-sectional design was used to assess 137 5-9-year-old obese children (mean +/- s.d. age = 8.3 +/- 1.1 years; mean BMI z-score = 2.76 +/- 0.70; 58% girls) from two regional cities in New South Wales, Australia, before commencement in a treatment trial. Correlates examined included age, BMI z, parental BMI, perceived competence, health-related quality of life, daily minutes spent in small screen recreation (SSR), and fundamental motor skill (FMS) proficiency. Physical activity was assessed using accelerometers and values were calculated for % of monitored time spent in moderate- (MPA) and vigorous (VPA)-intensity physical activity and mean counts per minute (CPM). Analyses were conducted separately for boys and girls. Motor skill proficiency was significantly correlated with a number of physical activity variables for boys and girls. For boys, regression analysis revealed object-control proficiency predicted CPM (R(2) = 0.25) and age was a predictor of %MPA (R(2) = 0.56). Age and object-control skill proficiency were salient predictors of %VPA (R(2) = 0.34). For girls, age and daily minutes of SSR were the only significant predictors for CPM (R(2) = 0.13). Age was the sole predictor of %MPA (R(2) = 0.38) and %VPA (R(2) = 0.15). The targeting of FMSs at an early age should be tested in experimental studies as potential strategies to increase physical activity among obese children, particularly for boys. Interventions aimed at reducing sedentary behaviors among obese girls should also be considered.     

Muscle force and power in obese and overweight children

The study investigated differences in skeletal muscle function between obese and non-obese children using a force platform. Forty obese children and adolescents (age range 8 to 18 years; 21 girls) and 40 age- and sex-matched controls performed two tests: (1) single two-legged jump, a countermovement jump for maximal height; (2) multiple one-legged hopping on the forefoot, a test of maximal force. In the single two-legged jump, obese subjects had higher absolute peak force (1.62 kN vs 1.09 kN) and peak power (2.46 kW vs 2.06 kW), but lower body weight-related peak force (2.10 vs 2.33) and lower peak power per body mass (30.9 W/kg vs 41.6 W/kg). Jump height (29.3 cm vs 37.5 cm) and maximal vertical velocity (1.92 ms(-1) vs 2.31 ms(-1)) were reduced in obese children. In multiple one-legged hopping, obese subjects had 72% and 84% higher absolute peak force on the left and right foot, respectively. However, forces relative to body weight were 24% and 23% lower in the obese group than in the control group. In conclusion, obese children and adolescents have increased muscle force and power. This partly compensates for the effect of high body weight on muscle performance.     

Physical activity compliance: differences between overweight/obese and normal-weight adults

Objectives: Comparisons of physical activity measured by accelerometers in overweight/obese adults and their normal‐weight counterparts are limited. Compliance with the 2002 Institute of Medicine (IOM) exercise recommendations for 60 minutes of moderate‐intensity exercise daily has not been reported. The purpose of this study was to compare physical activity, as measured by accelerometers, in overweight/obese adults vs. normal‐weight controls and to assess compliance with recommendations for physical activity by the IOM in 2002 and by the Centers for Disease Control and Prevention and American College of Sports Medicine in 1995 for 30 minutes of moderate‐intensity activity, preferably all days of the week. Research Methods and Procedures: Sixty‐two overweight/obese subjects, BMI ≥ 25, included 31 adults, 12 men and 19 women, 25 to 69 years old, and their normal‐weight controls, BMI 18.5 to 24.9, matched for gender, age, and height. Body composition was assessed using DXA. Physical activity was measured with Actigraph accelerometers (MTI, Fort Walton Beach, FL) worn by each participant for 7 consecutive days. Results: Accelerometry data indicated that overweight/obese adults recorded ～60 counts per minute less per day and spent 21 minutes less engaged in moderate or greater intensity activity than their normal‐weight counterparts. Although 71% to 94% of those studied met 1995 recommendations, only 13% of overweight/obese subjects and 26% of normal‐weight participants met 2002 exercise recommendations. Discussion: These results suggest that daily minutes spent in moderate‐intensity activity or greater are associated with weight status and that the 2002 IOM recommendations may be difficult to meet even for normal‐weight individuals.     

Behavioral pattern of overweight and obese school children

The aim of this study was to determine socio economic, health status, nutritional and behavioral differences in obese, overweight and normal weight children attending first grade elementary school. In overweight group there is 13.8% of boys and 12.6% of girls, in obese group 8.3% of boys and 6.9% of girls. In factor analysis 12 factors was excluded with cumulative loading of 60% variability. Discriminant analysis was performed with 12 factors as predictive variables and discriminant variables were three BMI groups: normal weight, overweight and obese. Function 1 discriminate well normal weight group from overweight and obese group. Overweight and obese groups is described with lower number of children in the family and lower order of birth, higher education of parents, they eat less vegetables and fruits, spend more time playing computer games, have less physical activity, drink more alcohol with their meals, exactly opposite to normal weight group.     

The declining prevalence of overweight among Russian children: Income, diet, and physical activity behavior changes

The aim of this study is to examine the relationships among income, diet, physical activity behaviors and overweight among Russian children during a period of economic upheaval. Subjects include 2151 schoolchildren aged 7-13 derived from cross-sectional waves of the Russia Longitudinal Monitoring Surveys in 1995 and in 2002. Diet was assessed by 24-h recall and physical activity (h/week) and household income by parental questionnaire. Hours spent in vigorous activities were low (1.0-1.5 h/week), and time spent in sedentary behaviors increased from 31 to 37 h/week between 1995 and 2002. In 1995 there was a direct relationship of income to energy and fat intake, and time spent in vigorous activity, and an inverse relationship of income to h/week spent in moderate activities (such as walking to school). The effect of having low income parents was less in 2002 than in 1995. Overweight prevalence did not differ significantly by income in either year, but there was a significant decline in overweight among high income children. Only hours spent in moderate physical activity was moderately protective against overweight. Income disparities do not explain trends in overweight among Russian children.     

Comparison of body composition methods in overweight and obese children.

The objective of the present study was to investigate the accuracy of percent body fat (%fat) estimates from dual-energy X-ray absorptiometry, air-displacement plethysmography (ADP), and total body water (TBW) against a criterion four-compartment (4C) model in overweight and obese children. A volunteer sample of 30 children (18 male and 12 female), age of (mean +/- SD) 14.10 +/- 1.83 yr, body mass index of 31.6 +/- 5.5 kg/m, and %fat (4C model) of 41.2 +/- 8.2%, was assessed. Body density measurements were converted to %fat estimates by using the general equation of Siri (ADPSiri) (Siri WE. Techniques for Measuring Body Composition. 1961) and the age- and gender-specific constants of Lohman (ADPLoh) (Lohman TG. Exercise and Sport Sciences Reviews. 1986). TBW measurements were converted to %fat estimates by assuming that water accounts for 73% of fat-free mass (TBW73) and by utilizing the age- and gender-specific water contents of Lohman (TBWLoh). All estimates of %fat were highly correlated with those of the 4C model (r > or = 0.95, P < 0.001; SE < or = 2.14). For %fat, the total error and mean difference +/- 95% limits of agreement compared with the 4C model were 2.50, 1.8 +/- 3.5 (ADPSiri); 1.82, -0.04 +/- 3.6 (ADPLoh); 2.86, -2.0 +/- 4.1 (TBW73); 1.90, -0.3 +/- 3.8 (TBWLoh); and 2.74, 1.9 +/- 4.0 DXA (dual-energy X-ray absorptiometry), respectively. In conclusion, in overweight and obese children, ADPLoh and TBWLoh were the most accurate methods of measuring %fat compared with a 4C model. However, all methods under consideration produced similar limits of agreement.     

Temporal associations between daytime physical activity and sleep in children

Objectives

We examined temporal associations between objectively-measured physical activity (PA) during the day and in the evening, and sleep quantity and quality.

Study Design

PA and sleep were measured by actigraphs for an average of one week in an epidemiological cohort study of 275 eight-year-old children.

Results

For each one standard deviation (SD) unit of increased PA during the day, sleep duration was decreased by 0.30, sleep efficiency by 0.16, and sleep fragmentation increased by 0.08 SD units that night. For each one SD unit increase in sleep duration and efficiency the preceding night, PA the following day decreased by 0.09 and 0.16 SD units, respectively. When we contrasted days with a high amount of moderate to vigorous activity during the day or in the evening to days with a more sedentary profile, the results were essentially similar. However, moderate to vigorous PA in the evening shortened sleep latency.

Conclusions

The relationship between a higher level of PA and poorer sleep is bidirectional. These within-person findings challenge epidemiological findings showing that more active people report better sleep. Since only a few studies using objective measurements of both PA and sleep have been conducted in children, further studies are needed to confirm/refute these results.     

Relationship between body composition, inflammation and lung function in overweight and obese asthma

Background

The obese-asthma phenotype is not well defined. The aim of this study was to examine both mechanical and inflammatory influences, by comparing lung function with body composition and airway inflammation in overweight and obese asthma.

Methods

Overweight and obese (BMI 28-40 kg/m²) adults with asthma (n = 44) completed lung function assessment and underwent full-body dual energy x-ray absorptiometry. Venous blood samples and induced sputum were analysed for inflammatory markers.

Results

In females, android and thoracic fat tissue and total body lean tissue were inversely correlated with expiratory reserve volume (ERV). Conversely in males, fat tissue was not correlated with lung function, however there was a positive association between android and thoracic lean tissue and ERV. Lower body (gynoid and leg) lean tissue was positively associated with sputum %neutrophils in females, while leptin was positively associated with android and thoracic fat tissue in males.

Conclusions

This study suggests that both body composition and inflammation independently affect lung function, with distinct differences between males and females. Lean tissue exacerbates the obese-asthma phenotype in females and the mechanism responsible for this finding warrants further investigation.     

A prospective study of overweight, physical activity, and depressive symptoms in young women

This study examined the prospective associations of BMI, physical activity (PA), changes in BMI, and changes in PA, with depressive symptoms. Self-reported data on height, weight, PA, selected sociodemographic and health variables and depressive symptoms (CESD-10) were provided in 2000 and 2003 by 6,677 young adult women (22-27 years in 2000) participating in the Australian Longitudinal Study on Women's Health (ALSWH). Results of logistic regression analyses showed that the odds of developing depressive symptoms at follow-up (2003) were higher in women who were overweight or obese in 2000 than in healthy weight women, and lower in women who were active in 2000 than in sedentary women. Changes in BMI were significantly associated with increased odds of depressive symptoms at follow-up. Sedentary women who increased their activity had lower odds of depressive symptoms at follow-up than those who remained sedentary. Increases in activity among initially sedentary young women were protective against depressive symptoms even after adjusting for BMI changes. These findings indicate that overweight and obese young women are at risk of developing depressive symptoms. PA appears to be protective against the development of depressive symptoms, but does not attenuate the depressive symptoms associated with weight gain. However, among initially sedentary young women, even small increases in PA over time may reduce the odds of depressive symptoms, regardless of weight status.     

Central orexin sensitivity, physical activity, and obesity in diet-induced obese and diet-resistant rats

Nonexercise activity thermogenesis (NEAT), the most variable component of energy expenditure, can account for differential capacities for human weight gain. Also highly variable, spontaneous physical activity (SPA) may similarly affect weight balance in animals. In the following study, we utilized the rat model of obesity, the diet-induced obese (DIO) rat, as well as the diet-resistant (DR) rat strain, to investigate how access to a high-fat diet alters SPA and the associated energy expenditure (i.e., NEAT). DIO and DR rats showed no differences in the amount of SPA before access to the high-fat diet. After 29 days on a high-fat diet, the DIO rats showed significant decreases in SPA, whereas the DR rats did not. Next, we wanted to determine whether the DIO and DR rats showed differential sensitivity to microinjections of orexin into the paraventricular nucleus of the hypothalamus (PVN). Unilateral guide cannulae were implanted, aimed at the PVN. Orexin A (0, 0.125, 0.25, and 1.0 nmol in 500 nl) was microinjected through the guide cannula into the PVN, then SPA and energy expenditure were measured for 2 h. Using the response to vehicle as a baseline, the DR rats showed significantly greater increase in NEAT compared with the DIO rats. These data indicate that diet-induced obesity is associated with decreases in SPA and a lack of increase in NEAT. A putative mechanism for changes in NEAT that accompany obesity is a decreased sensitivity to the NEAT-activating effects of neuropeptides such as orexin.     

Cost-effectiveness of a family-based GP-mediated intervention targeting overweight and moderately obese children

Objective

To assess from a societal perspective the incremental cost-effectiveness of a family-based GP-mediated intervention targeting overweight and moderately obese children. The intervention was modelled on the LEAP (live, eat and play) trial, a randomised controlled trial conducted by the Centre for Community Child Health, Melbourne, Australia in 2002-2003. This study was undertaken as part of the assessing cost-effectiveness (ACE) in obesity project which evaluated, using consistent methods, 13 interventions targeting unhealthy weight gain in children and adolescents.

Method

A logic pathway was used to model the effects of the intervention compared to no intervention on body mass index (BMI) and health outcomes (disability-adjusted life years—DALYs). Disease costs and health benefits were tracked until the cohort of eligible children reached the age of 100 years or death. Simulation-modelling techniques were used to present a 95% uncertainty interval around the cost-effectiveness ratio. The intervention was also assessed against a series of filters (‘equity’, ‘strength of evidence’, ‘acceptability’, ‘feasibility’, sustainability’ and ‘side-effects’) to incorporate additional factors that impact on resource allocation decisions.

Results

The intervention, as modelled, reached 9685 children aged 5-9 years with a BMI z-score of ≥3.0, and cost $AUD6.3M (or $AUD4.8M excluding time costs). It resulted in an incremental saving of 2300 BMI units which translated to 511 DALYs. The cost-offsets stemming from the intervention totalled $AUD3.6M, resulting in a net cost per DALY saved of $AUD4670 (dominated; $0.1M) (dominated means intervention costs more for less effect).

Conclusion

Compared to a ‘no intervention’ control group, the intervention was cost-effective under current assumptions, although the uncertainty intervals were wide. A key question related to the long-term sustainability of the small incremental weight loss reported, based on the 9-month follow-up results for LEAP.     

Antioxidant superoxide dismutase activity in obese children

The aim of the study was to evaluate the antioxidative Cu/Zn-SOD (superoxide dismutase) response to obesity-related stress in obese children compared to a similar-aged control group. Forty-eight exogenic obese children and 11 healthy children were compared for red cell Cu/Zn-SOD, glucose, and lipid profiles and the relations between the were investigated. Antioxidant response as Cu/Zn-SOD was significantly higher in the obese group (p<0.05). Although glucose and lipid levels were statistically higher in the obese group, a certain relation with the SOD level was not established in childhood. This is the first study showing the oxidative stress caused by obesity and related antioxidative response even in the childhood period. Interventions, including diet modifications, should be kept in mind to diminish the obesity-related oxidative stress from the childhood period.