Body fatness and physical activity levels of young children

Impact of Physical Activity-Based Interventions on Children and Adolescents' Physical Self-Concept: A Meta-Analysis

Background: Observational studies associate physical activity (PA) with improved perceptions of children and adolescents' physical self-concept (PSC) and global self-concept (GSC). However, only a few PA-based interventions exist for improving PSC and their results have been inconclusive. Objective: To determine the effect of specific PA-based programmes on the PSC (including its sub-dimensions) and GSC of children and adolescents, and to assess possible moderators. Methods: The databases Web of Science, Scopus, SportDiscus, PubMed, CINAHL, and Cochrane Library were reviewed in February 2020. Only studies with pre-post measurements and control groups were included. The impact of PA-based interventions was explored through different meta-analyses and moderator analyses. Results: Altogether, 20 studies were included in the meta-analysis. Positive and significant effects of PA were determined on self-perceived physical appearance (g = 0.13; 95% CI = 0.03, 0.23), self-perceived sport competence (g = 0.30; 95% CI = 0.09, 0.51), self-perceived physical fitness (g = 0.19; 95% CI = 0.05, 0.32), PSC (g = 0.31; 95% CI = 0.10, 0.52), and GSC (g = 0.17; 95% CI = 0.01, 0.33). The existence of additional interventions in PA-based programmes (e.g., interventions focused on psychological factors or healthy habits) moderated the influence of PA on self-perceived sport competence and physical fitness. Moreover, environment and time were distinguished as moderators for self-perceived physical appearance and sport competence. Further, intervention type, gender, and frequency of intervention moderated the effects of PA on PSC. Conclusions: PA-based interventions, especially in school, seem to be beneficial for the development of positive physical self-perceptions.

Proportion of Chinese Children and Adolescents Meeting 24-Hour Movement Guidelines and Associations with Overweight and Obesity

Background: Since there is little knowledge about the 24-hour movement behaviors of Chinese children and adolescents, the purposes of this study were to investigate the proportion of Chinese children and adolescents meeting the 24-Hour Movement Guidelines and to further evaluate its relationship with overweight and obesity. Methods: A total of 440 children and adolescents aged 7−18 years from 7 cities in China were selected to measure physical activity using accelerometers, and sleep (SLP) and screen time (ST) using questionnaires. The data were analyzed with the independent T-test, Mann−Whitney U test, Cox−Stuart test, chi-square test, and logistic regression. Results: The proportion of Chinese children and adolescents meeting the overall 24-Hour Movement Guidelines was 7.3%. Boys (11.8%) were higher than girls (3.4%) (p < 0.001) and showed a downward trend with age (Ptrend = 0.03). The rates of overweight and obesity among children and adolescents who met the ST, MVPA + ST, ST + SLP, and MVPA + SLP + ST guidelines were 39%, 15%, and 36%, and 25% did not meet any guidelines. The rates of overweight and obesity among those who met 1, 2, and 3 guidelines were lower than the rate among those who did not meet any guidelines (odds ratio (OR) = 0.51, 95% confidence interval (CI): 0.22−1.17; OR = 0.32, 95% CI: 0.13−0.77; OR = 0.23, 95% CI: 0.07−0.81) and showed a decreasing trend (Ptrend = 0.006). Conclusions: The proportion of Chinese children and adolescents meeting the overall 24-Hour Movement Guidelines was low. The rate of overweight and obesity among children and adolescents who met the overall 24-Hour Movement Guidelines was the lowest compared with the rates among those who met any one or two. There was a dose−response relationship between the number of guidelines met and the overweight and obesity rate.

A Systematic Review of Children's Physical Activity Patterns: Concept, Operational Definitions, Instruments, Statistical Analyses, and Health Implications

Despite the widespread use of the expression “physical activity pattern” (PAP), there apparently is no general consensus regarding its definition. This systematic review aimed to examine available research focussing on (1) definitions of PAP, (2) instruments/techniques used to describe PAP, (3) statistical approaches used to analyse PAP, and (4) implications of PAP on children’s health. A systematic review of the available literature was done to identify studies published up to October 2019, and 76 studies were eligible. None of the studies presented a formal definition of PAP; a wide range of instruments were used to investigate children’s PAP, and most of the revised studies did not explicitly present a formal statistical model to define PAP. Twenty-four papers purported to examine associations between PAP and health indicators. The review highlights no consensus on a clear PAP definition whatever the instrument used to capture it, and we did not find any agreement regarding how best to analyse PAP. We suggest that PAP should be used when targeting the investigation of similarities/dissimilarities, as well as stabilities and/or changes in children’s PA at an intra-personal level. In sum, PAP should be used to best describe individual streams of behaviours, and not exclusively PA levels/intensities.

Interventions for preventing obesity in children

EDITORIAL NOTE

This Cochrane review is now out of date and should not be used for reference. It has been split into four age groups and updated. Please refer to the 5‐11 and 12‐18 age group Cochrane reviews which were published in May 2024: https://doi.org/10.1002/14651858.CD015328.pub2 https://doi.org/10.1002/14651858.CD015330.pub2 The 2‐4 age group Cochrane review is planned for publication in September 2024.

BACKGROUND

Prevention of childhood obesity is an international public health priority given the significant impact of obesity on acute and chronic diseases, general health, development and well-being. The international evidence base for strategies to prevent obesity is very large and is accumulating rapidly. This is an update of a previous review.

OBJECTIVES

To determine the effectiveness of a range of interventions that include diet or physical activity components, or both, designed to prevent obesity in children.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, PsychINFO and CINAHL in June 2015. We re-ran the search from June 2015 to January 2018 and included a search of trial registers.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of diet or physical activity interventions, or combined diet and physical activity interventions, for preventing overweight or obesity in children (0-17 years) that reported outcomes at a minimum of 12 weeks from baseline.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data, assessed risk-of-bias and evaluated overall certainty of the evidence using GRADE. We extracted data on adiposity outcomes, sociodemographic characteristics, adverse events, intervention process and costs. We meta-analysed data as guided by the Cochrane Handbook for Systematic Reviews of Interventions and presented separate meta-analyses by age group for child 0 to 5 years, 6 to 12 years, and 13 to 18 years for zBMI and BMI.

MAIN RESULTS

We included 153 RCTs, mostly from the USA or Europe. Thirteen studies were based in upper-middle-income countries (UMIC: Brazil, Ecuador, Lebanon, Mexico, Thailand, Turkey, US-Mexico border), and one was based in a lower middle-income country (LMIC: Egypt). The majority (85) targeted children aged 6 to 12 years.Children aged 0-5 years: There is moderate-certainty evidence from 16 RCTs (n = 6261) that diet combined with physical activity interventions, compared with control, reduced BMI (mean difference (MD) -0.07 kg/m2, 95% confidence interval (CI) -0.14 to -0.01), and had a similar effect (11 RCTs, n = 5536) on zBMI (MD -0.11, 95% CI -0.21 to 0.01). Neither diet (moderate-certainty evidence) nor physical activity interventions alone (high-certainty evidence) compared with control reduced BMI (physical activity alone: MD -0.22 kg/m2, 95% CI -0.44 to 0.01) or zBMI (diet alone: MD -0.14, 95% CI -0.32 to 0.04; physical activity alone: MD 0.01, 95% CI -0.10 to 0.13) in children aged 0-5 years.Children aged 6 to 12 years: There is moderate-certainty evidence from 14 RCTs (n = 16,410) that physical activity interventions, compared with control, reduced BMI (MD -0.10 kg/m2, 95% CI -0.14 to -0.05). However, there is moderate-certainty evidence that they had little or no effect on zBMI (MD -0.02, 95% CI -0.06 to 0.02). There is low-certainty evidence from 20 RCTs (n = 24,043) that diet combined with physical activity interventions, compared with control, reduced zBMI (MD -0.05 kg/m2, 95% CI -0.10 to -0.01). There is high-certainty evidence that diet interventions, compared with control, had little impact on zBMI (MD -0.03, 95% CI -0.06 to 0.01) or BMI (-0.02 kg/m2, 95% CI -0.11 to 0.06).Children aged 13 to 18 years: There is very low-certainty evidence that physical activity interventions, compared with control reduced BMI (MD -1.53 kg/m2, 95% CI -2.67 to -0.39; 4 RCTs; n = 720); and low-certainty evidence for a reduction in zBMI (MD -0.2, 95% CI -0.3 to -0.1; 1 RCT; n = 100). There is low-certainty evidence from eight RCTs (n = 16,583) that diet combined with physical activity interventions, compared with control, had no effect on BMI (MD -0.02 kg/m2, 95% CI -0.10 to 0.05); or zBMI (MD 0.01, 95% CI -0.05 to 0.07; 6 RCTs; n = 16,543). Evidence from two RCTs (low-certainty evidence; n = 294) found no effect of diet interventions on BMI.Direct comparisons of interventions: Two RCTs reported data directly comparing diet with either physical activity or diet combined with physical activity interventions for children aged 6 to 12 years and reported no differences.Heterogeneity was apparent in the results from all three age groups, which could not be entirely explained by setting or duration of the interventions. Where reported, interventions did not appear to result in adverse effects (16 RCTs) or increase health inequalities (gender: 30 RCTs; socioeconomic status: 18 RCTs), although relatively few studies examined these factors.Re-running the searches in January 2018 identified 315 records with potential relevance to this review, which will be synthesised in the next update.

AUTHORS' CONCLUSIONS

Interventions that include diet combined with physical activity interventions can reduce the risk of obesity (zBMI and BMI) in young children aged 0 to 5 years. There is weaker evidence from a single study that dietary interventions may be beneficial.However, interventions that focus only on physical activity do not appear to be effective in children of this age. In contrast, interventions that only focus on physical activity can reduce the risk of obesity (BMI) in children aged 6 to 12 years, and adolescents aged 13 to 18 years. In these age groups, there is no evidence that interventions that only focus on diet are effective, and some evidence that diet combined with physical activity interventions may be effective. Importantly, this updated review also suggests that interventions to prevent childhood obesity do not appear to result in adverse effects or health inequalities.The review will not be updated in its current form. To manage the growth in RCTs of child obesity prevention interventions, in future, this review will be split into three separate reviews based on child age.

Relationship Between Obesity, Physical Activity, and Cardiorespiratory Fitness Levels in Children and Adolescents in Bosnia and Herzegovina: An Analysis of Gender Differences

This study aimed to examine: (i) the level of physical activity (PA), obesity indices and cardiorespiratory fitness (CRF) among boys and girls in primary school, and (ii) to determine the association of obesity indices and PA with CRF for the total number of participants, and then separately for boys and girls. 753 sixth to ninth grade girls and boys aged 10-14 years took part in this cross-sectional study. The PA was assessed by the "Physical Activity Questionnaire - Children" and CRF was assessed by the Maximal multistage a 20 m shuttle run test. Body mass index (BMI), waist circumferences (WC), and waist to height ratio (WHtR) were considered as obesity indices. Multiple linear regression analyses were performed to explore correlates of CRF. The results obtained showed the prevalence of general overweight and obesity was 25.5% in our sample which was lower than that in the regional estimate (e.g., ∼28%) for Eastern Europe. Among all participants, CRF was associated with male sex, older age, a lower WC percentile, higher WHtR, and higher level of PA. The model accounted for 24% of the variance. CRF was associated with older age and higher level of PA among girls and boys. Lower WC percentile was a significant determinant of CRF among boys. In conclusion, general overweight/obesity was not independently associated with CRF. Those with better CRF were more likely to be male and older, had a higher level of PA and lower central adiposity. These findings emphasize the importance of supporting school age children to take a part in programmed physical activity regardless of their body composition.

Objectively Measured Physical Activity and Health-Related Physical Fitness in Secondary School-Aged Male Students With Autism Spectrum Disorders

BACKGROUND

Recent evidence suggests that childhood obesity is increasing in children with typical development (TD) and in children with autism spectrum disorders (ASD). The associations between physical activity (PA) levels and physical fitness components have not yet been objectively examined in this population but may have clinical implications for the development of secondary health complications.

OBJECTIVE

The aims of this study were: (1) to compare PA and physical fitness between secondary school-aged male students with ASD and their peers with TD and (2) to assess possible interrelationships between PA and physical fitness levels in each group.

DESIGN

This was a cross-sectional study.

METHODS

Physical activity was recorded every 10 seconds by using accelerometry in 70 male students with (n=35) and without (n=35) ASD for up to 5 weekdays and 2 weekend days. The Brockport Physical Fitness Test was used to assess physical fitness.

RESULTS

The primary findings were: (1) participants with ASD were less physically active overall and engaged in moderate-to-vigorous PA for a lower percentage of time compared with participants with TD during weekdays; (2) participants with ASD had significantly lower scores on all physical fitness measures, except body composition; and (3) group-dependent relationships existed between physical fitness profiles and PA levels.

LIMITATIONS

The study design limits causal inference from the results.

CONCLUSION

Specific interventions for maximizing PA and physical fitness levels in secondary school-aged male students with ASD are urgently needed.

Short-term Effects of a Physical Activity Intervention on Obesity and Cardiovascular Fitness of 12-14-year-old Boy Students

BACKGROUND

Some local governments have implemented strategies to increase physical activity as a way to control obesity in children, but in Iranian students few studies have evaluated the effects of such interventions on overweight and obese children. The aim of this study was to evaluate the effects of a short-term school-based physical activity on obesity and cardiovascular fitness in 12-14-year-old boy students.

METHODS

This study showed an intervention effect on some health-related fitness factors in students. A number of 127 boy students aged 12-14 years, in the city of Isfahan, based on preventive plan of inactivity in children at the provincial Health office selected randomly as subjects. Measurement variables include; weight, height, body mass index (BMI), waist-hip ratio (WHR), body-fat percent and aerobic power of subjects measured by valid tests.

RESULTS

This study revealed that body-fat percentage of this students changed near to 17.84% (42.25% pretest vs. 34.71% posttest), WHR 0.44%, (0.915 pretest vs. 0.911 posttest), VO2 max changed 8.54% (27.84 pretest vs. 30.22 posttest) whereas BMI was changed 2.61% (26.81 pretest vs. 26.03 posttest). Results also revealed that there were significant differences between fat percent, (P = 0.001) and VO2 max (P = 0.001), but there was no difference between BMI of subjects in pre and posttests (P = 0.452).

CONCLUSIONS

Findings of this study signify that an implementation of short-term intervention components in the school system may have a beneficial effect on body-fat percentage and cardiovascular fitness of overweight/obese children.

Correlation between Aerobic Fitness and Body Composition in Middle School Students

Background:

Since correlations have been found between body composition and physical activity in different parts of the world, inactivity and poor physical condition likely contributes main factors in childhood obesity. This study was implemented to determine the relationship between cardiovascular fitness and body-composition in a group of Iranian middle school students.

Methods:

In this descriptive study, subjects comprised of 12,946 students (10,531 girls and 2,415 boys aged 11–13 years) in the city of Isfahan. Height, weight, body-fat percent, body mass index, and cardiovascular fitness of the aforesaid students were measured by valid tests.

Results:

This study showed that fat percentage and aerobic fitness (VO₂ max) of girls were 24.73%, and 29.5 (ml/kg/min) and boys19.32% and 36.4 (ml/kg/min) respectively. Results also revealed that there was a negative significant correlation between fat percent and aerobic fitness of boys (r = −0.81), and girls (r = −0.77) respectively.

Conclusions:

To conclude, this study signifies that fat percentage augmentation leads to a decrease in aerobic fitness of children. Thus, fat percentage can be associated with different chronic diseases such as cardiovascular ones.

Short-term Effects of a Physical Activity Intervention on Obesity and Aerobic Fitness of Adolescent Girls

Background:

In the past two decades, physical activity has decreased during both childhood and adolescence, and particularly adolescence. It seems that schools are attractive settings in which to implement interventions designed in order to promote physical activity in children; but in Iranian students, few studies have evaluated the effects of such interventions on overweight and obese children. The aim of this study was to evaluate the effects of a short-term school-based physical activity on obesity and aerobic fitness in 12–14 years aged girls.

Methods:

This is a study with single group pretest and posttest design, in which 129 middle school girls in city of Isfahan were assessed based on preventive plan of inactivity in children at the Provincial Health Office. Variables, including weight, height, body mass index (BMI), waist-hip ratio (WHR), body fat percentage and aerobic power of subjects were measured using valid tests.

Results:

This study showed that subjects’ body fat percentage changed about 3.6% (37.74% pretest vs. 36.39% posttest), VO₂ max changed 7.43% (29.72 pretest vs. 31.93 posttest), WHR changed 1.12% (0.89 pretest vs. 0.88 posttest), whereas BMI was changed 1.65% (27.80 pretest vs. 27.34 posttest). Findings also revealed that there were significant differences between fat percent, (P = 0.001) and VO₂ max (P = 0.001) of subjects, but there was no difference between BMI of them in pre- and post-tests (P = 0.361).

Conclusions:

These results suggest that even a short-term exercise intervention may lead to positive changes in body fat percentage, WHR and aerobic fitness of overweight children. Therefore, school-based physical activity interventions can be an effective preventive strategy to control obesity and overweight in students.

Objectively measured activity in 8-10-year-old Turkish children: relationship to health-related fitness

BACKGROUND

No objective data regarding the physical activity (PA) levels of young Turkish children currently exist. Furthermore, whether habitual PA is associated with the components of health-related fitness among children is unclear. The aim of this study was to evaluate the patterns and levels of objectively measured PA in prepubertal Turkish children and its relationship with body fatness, aerobic and anaerobic fitness.

METHODS

Eighty-nine 8-10-year-old children (47 boys and 42 girls) participated in this study. The intensity, duration and frequency of PA were assessed from 4 days of heart rate monitoring with 15 s sampling intervals. Body fatness was determined by measuring skinfold thickness. Anaerobic fitness was evaluated using the Wingate test. All the children performed the shuttle run test to assess aerobic fitness.

RESULTS

The PA of boys was significantly higher than that of girls (P < 0.05). Gender difference is more marked for vigorous PA. Instead of sustained PA, short bouts of PA, lasting up to 1 min, were characteristic of PA patterns of children. The duration and frequency of PA were positively related to aerobic fitness and negatively related to fatness for both gender groups (P < 0.05). These relationships were more prominent for accumulated PA than for other measures of PA. No relationship was obtained between PA and anaerobic fitness in either gender group (P > 0.05).

CONCLUSIONS

Intermittent, accumulated moderate intensity PA may be more important than sustained vigorous intensity PA in influencing children's fitness and fatness levels. Detailed studies are needed to clarify which dimension of PA is more beneficial for health-related fitness in children.

School-based physical activity programs for promoting physical activity and fitness in children and adolescents aged 6 to 18

BACKGROUND

The World Health Organization (WHO) estimates that 1.9 million deaths worldwide are attributable to physical inactivity and at least 2.6 million deaths are a result of being overweight or obese. In addition, WHO estimates that physical inactivity causes 10% to 16% of cases each of breast cancer, colon, and rectal cancers as well as type 2 diabetes, and 22% of coronary heart disease and the burden of these and other chronic diseases has rapidly increased in recent decades.

OBJECTIVES

The purpose of this systematic review was to summarize the evidence of the effectiveness of school-based interventions in promoting physical activity and fitness in children and adolescents.

SEARCH METHODS

The search strategy included searching several databases to October 2011. In addition, reference lists of included articles and background papers were reviewed for potentially relevant studies, as well as references from relevant Cochrane reviews. Primary authors of included studies were contacted as needed for additional information.

SELECTION CRITERIA

To be included, the intervention had to be relevant to public health practice (focused on health promotion activities), not conducted by physicians, implemented, facilitated, or promoted by staff in local public health units, implemented in a school setting and aimed at increasing physical activity, included all school-attending children, and be implemented for a minimum of 12 weeks. In addition, the review was limited to randomized controlled trials and those that reported on outcomes for children and adolescents (aged 6 to 18 years). Primary outcomes included: rates of moderate to vigorous physical activity during the school day, time engaged in moderate to vigorous physical activity during the school day, and time spent watching television. Secondary outcomes related to physical health status measures including: systolic and diastolic blood pressure, blood cholesterol, body mass index (BMI), maximal oxygen uptake (VO2max), and pulse rate.

DATA COLLECTION AND ANALYSIS

Standardized tools were used by two independent reviewers to assess each study for relevance and for data extraction. In addition, each study was assessed for risk of bias as specified in the Cochrane Handbook for Systematic Reviews of Interventions. Where discrepancies existed, discussion occurred until consensus was reached. The results were summarized narratively due to wide variations in the populations, interventions evaluated, and outcomes measured.

MAIN RESULTS

In the original review, 13,841 records were identified and screened, 302 studies were assessed for eligibility, and 26 studies were included in the review. There was some evidence that school-based physical activity interventions had a positive impact on four of the nine outcome measures. Specifically positive effects were observed for duration of physical activity, television viewing, VO2 max, and blood cholesterol. Generally, school-based interventions had little effect on physical activity rates, systolic and diastolic blood pressure, BMI, and pulse rate. At a minimum, a combination of printed educational materials and changes to the school curriculum that promote physical activity resulted in positive effects.In this update, given the addition of three new inclusion criteria (randomized design, all school-attending children invited to participate, minimum 12-week intervention) 12 of the original 26 studies were excluded. In addition, studies published between July 2007 and October 2011 evaluating the effectiveness of school-based physical interventions were identified and if relevant included. In total an additional 2378 titles were screened of which 285 unique studies were deemed potentially relevant. Of those 30 met all relevance criteria and have been included in this update. This update includes 44 studies and represents complete data for 36,593 study participants. Duration of interventions ranged from 12 weeks to six years.Generally, the majority of studies included in this update, despite being randomized controlled trials, are, at a minimum, at moderate risk of bias. The results therefore must be interpreted with caution. Few changes in outcomes were observed in this update with the exception of blood cholesterol and physical activity rates. For example blood cholesterol was no longer positively impacted upon by school-based physical activity interventions. However, there was some evidence to suggest that school-based physical activity interventions led to an improvement in the proportion of children who engaged in moderate to vigorous physical activity during school hours (odds ratio (OR) 2.74, 95% confidence interval (CI), 2.01 to 3.75). Improvements in physical activity rates were not observed in the original review. Children and adolescents exposed to the intervention also spent more time engaged in moderate to vigorous physical activity (with results across studies ranging from five to 45 min more), spent less time watching television (results range from five to 60 min less per day), and had improved VO2max (results across studies ranged from 1.6 to 3.7 mL/kg per min). However, the overall conclusions of this update do not differ significantly from those reported in the original review.

AUTHORS' CONCLUSIONS

The evidence suggests the ongoing implementation of school-based physical activity interventions at this time, given the positive effects on behavior and one physical health status measure. However, given these studies are at a minimum of moderate risk of bias, and the magnitude of effect is generally small, these results should be interpreted cautiously. Additional research on the long-term impact of these interventions is needed.

Interventions for preventing obesity in children

BACKGROUND

Prevention of childhood obesity is an international public health priority given the significant impact of obesity on acute and chronic diseases, general health, development and well-being. The international evidence base for strategies that governments, communities and families can implement to prevent obesity, and promote health, has been accumulating but remains unclear.

OBJECTIVES

This review primarily aims to update the previous Cochrane review of childhood obesity prevention research and determine the effectiveness of evaluated interventions intended to prevent obesity in children, assessed by change in Body Mass Index (BMI). Secondary aims were to examine the characteristics of the programs and strategies to answer the questions "What works for whom, why and for what cost?"

SEARCH METHODS

The searches were re-run in CENTRAL, MEDLINE, EMBASE, PsychINFO and CINAHL in March 2010 and searched relevant websites. Non-English language papers were included and experts were contacted.

SELECTION CRITERIA

The review includes data from childhood obesity prevention studies that used a controlled study design (with or without randomisation). Studies were included if they evaluated interventions, policies or programs in place for twelve weeks or more. If studies were randomised at a cluster level, 6 clusters were required.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias of included studies.  Data was extracted on intervention implementation, cost, equity and outcomes. Outcome measures were grouped according to whether they measured adiposity, physical activity (PA)-related behaviours or diet-related behaviours.  Adverse outcomes were recorded. A meta-analysis was conducted using available BMI or standardised BMI (zBMI) score data with subgroup analysis by age group (0-5, 6-12, 13-18 years, corresponding to stages of developmental and childhood settings).

MAIN RESULTS

This review includes 55 studies (an additional 36 studies found for this update). The majority of studies targeted children aged 6-12 years.  The meta-analysis included 37 studies of 27,946 children and demonstrated that programmes were effective at reducing adiposity, although not all individual interventions were effective, and there was a high level of observed heterogeneity (I(2)=82%).  Overall, children in the intervention group had a standardised mean difference in adiposity (measured as BMI or zBMI) of -0.15kg/m(2) (95% confidence interval (CI): -0.21 to -0.09).  Intervention effects by age subgroups were -0.26kg/m(2) (95% CI:-0.53 to 0.00) (0-5 years), -0.15kg/m(2) (95% CI -0.23 to -0.08) (6-12 years), and -0.09kg/m(2) (95% CI -0.20 to 0.03) (13-18 years). Heterogeneity was apparent in all three age groups and could not explained by randomisation status or the type, duration or setting of the intervention.  Only eight studies reported on adverse effects and no evidence of adverse outcomes such as unhealthy dieting practices, increased prevalence of underweight or body image sensitivities was found.  Interventions did not appear to increase health inequalities although this was examined in fewer studies.

AUTHORS' CONCLUSIONS

We found strong evidence to support beneficial effects of child obesity prevention programmes on BMI, particularly for programmes targeted to children aged six to 12 years. However, given the unexplained heterogeneity and the likelihood of small study bias, these findings must be interpreted cautiously. A broad range of programme components were used in these studies and whilst it is not possible to distinguish which of these components contributed most to the beneficial effects observed, our synthesis indicates the following to be promising policies and strategies:·         school curriculum that includes healthy eating, physical activity and body image·         increased sessions for physical activity and the development of fundamental movement skills throughout the school week·         improvements in nutritional quality of the food supply in schools·         environments and cultural practices that support children eating healthier foods and being active throughout each day·         support for teachers and other staff to implement health promotion strategies and activities (e.g. professional development, capacity building activities)·         parent support and home activities that encourage children to be more active, eat more nutritious foods and spend less time in screen based activitiesHowever, study and evaluation designs need to be strengthened, and reporting extended to capture process and implementation factors, outcomes in relation to measures of equity, longer term outcomes, potential harms and costs.Childhood obesity prevention research must now move towards identifying how effective intervention components can be embedded within health, education and care systems and achieve long term sustainable impacts.  

Physical activity levels and energy expenditure of 9-year-old – 12-year-old overweight and obese children

The high occurrence of overweight and obesity amongst children is a disturbing health problem worldwide. Possible causes of increasing childhood obesity are inactivity and energy imbalances. The aim of this study was to analyse the total energy expenditure (TEE)and physical activity levels in 9-year-old – 12-year-old overweight and obese children during a weekday and a weekend day, as well as during a weekday morning and afternoon. Twenty-four 9-year-old – 12-year-old children (seven boys and 17 girls), of whom nine were overweight and 15 were obese, were selected from seven public primary schools for this study. Body mass index (BMI) cut-off points were used to distinguish between overweight and obese. Each participant wore an ACTICAL™ monitor to determine their physical activity levels and TEE. It was found that the TEE of the children did not differ between a week day and a weekend day, although the TEE of the week day afternoon differed significantly from that of the weekday morning. Unlike the overweight children, none of the obese children met the requirements of 60 minutes of moderate-intensity physical activity per day. Strategies should be found to increase the activity levels of overweight and, especially, obese children, specifically during the mornings and over weekends.OpsommingDie hoë voorkoms van oorgewig en obesiteit onder kinders is wêreldwyd ’n kommerwekkende gesondheidsprobleem. Fisieke onaktiwiteit en energiewanbalanse word as moontlike oorsake van die probleem beskou. Die doel van hierdie studie was om die totale energieverbruik (TEV) en fisieke-aktiwiteitsvlakke van 9-jarige – 12-jarige oorgewig- en obese kinders tydens ‘n totale weeksdag en naweekdag te ontleed, asook tydens die oggend en middag van ‘n weeksdag. Vier-en-twintig 9-jarige – 12-jarige kinders (sewe seuns en 17 dogters), waarvan nege oorgewig en 15 obees was, is uit sewe publieke laerskole vir die studie gekies. Afsnypunte volgens die liggaamsmassa-indeks (LMI) is gebruik om tussen oorgewig en obees te onderskei. Elke deelnemer het ‘n ACTICAL™ monitor gedra om hul fisieke-aktiwiteitsvlakke en TEV te bepaal. Die studie het getoon dat die TEV van die kinders op ’n weeksdag en naweekdag nie verskil het nie, alhoewel TEV tydens die middag van die weeksdag betekenisvol verskil het van die oggend s’n. Anders as die oorgewig kinders, het geen van die obese kinders aan die voorgestelde riglyn van 60 minute se matig intensiewe fisieke aktiwiteit per dag voldoen nie. Strategieë moet gevind word om die vlakke van aktiwiteit van oorgewig en veral obese kinders te verhoog, spesifiek gedurende die oggende en oor naweke.

On some novel aspects of consanguineous marriages

Consanguineous marriages, often viewed as incestuous and objectionable, are more widespread than commonly perceived. They integrate multiple facets of human adaptation: economic, cultural and genetic. The widely touted explanation for the origin and persistence of consanguinity is that it provides many socioeconomic benefits; however, this view may be too simplistic. The bias against consanguinity may preclude an objective understanding of this sociobiological puzzle. Inbreeding increases the speed of selection of beneficial recessive and co-dominant alleles, e.g. those that protect against diseases. In populations endemic with malaria, the prevalence of consanguineous marriages and the frequency of alleles protective against malaria are both very high. Thus, consanguinity could theoretically increase the relative fitness of a population under specific ecological conditions; sometimes, the overall genetic benefits may exceed genetic costs of inbreeding. We discuss some recent evidence from studies on inbreeding along with the reasons responsible for the mating strategy found in some human populations. We contend that a better appreciation of our inherent biases and potential genetic benefits of inbreeding in specific ecological conditions would help us to appreciate the wider picture of consanguinity.

An investigation of patterns of children's sedentary and vigorous physical activity throughout the week

BACKGROUND

Participation in higher intensity activity (i.e. vigorous physical activity [VPA]) appears more consistently associated with lower adiposity, unfortunately little is known about the nature and patterns of VPA participation in children.

OBJECTIVE

To examine the volume and patterns of vigorous and sedentary activity during different segments of the week (weekend, school-based and out-of-school). We also investigated differences by sex, socioeconomic status (SES) and weight status.

DESIGN

A cross-sectional study including 1568 UK children aged 9-10 years.

OUTCOME MEASURES

Sedentary activity (mins), total activity (counts/min) and VPA (mins) were measured by accelerometry. Using a series of 2 level mixed effects linear regression models we tested differences across the segmented week (school time [0900-1500] vs. out-of-school time [0700-0900 & 1500-2100]; and weekday vs. weekend); all models were adjusted for sex, weight status (gender- and age-specific body mass index [BMI] cut points), SES, age and accelerometer registered wear time.

RESULTS

Boys and girls accumulated higher VPA out-of-school compared to during school (boys mean ± SD 16.9 ± 9.6 vs 12.6 ± 5.8; girls, 13.1 ± 7.7 vs 8.2 ± 4.0, both p < 0.001); but there were no differences for weekday v weekend VPA (p > 0.05). Less time was spent sedentary on weekdays compared to weekends (p < 0.001). Although boys were more physically active and girls accumulated more sedentary time, the overall pattern in which their physical activity intensity varied across the various day segments was similar when stratified by weight status and SES; and large volumes of sedentary time were observed each hour across the day.

CONCLUSIONS

The promotion of VPA during the weekend may hold the greatest promise for increasing VPA. Interventions aimed at increasing physical activity in 9-10 year old children should aim to target all children independent of sex, SES or weight status.

Physical activity and body mass index of school children and adolescents in Abeokuta, Southwest Nigeria

BACKGROUND

Physical inactivity and sedentary lifestyles are known to predispose to overweight and obesity. These lifestyles are also known to track from childhood into adulthood with consequent cardiovascular and metabolic problems. This study aimed to describe the frequency of physical activity and the relationship between physical activity and body mass index of urban Nigerian school children and adolescents.

METHODS

Children from seven schools in Abeokuta, southwest Nigeria were selected using a multi-staged random sampling technique.

RESULTS

Of 570 children, 411 (72.1%) were involved in moderate to vigorous physical activities. Involvement in physical activity was higher in older children (P<0.001), males (P<0.001), and children of mothers with a higher educational level (P=0.03). Eleven (1.9%) children were overweight or obese whereas 163 (28.6%) were underweight. There were more children with underweight than overweight among the subject population with a high level of physical activity (35.6% vs. 4.4%, P=0.499).

CONCLUSIONS

A large proportion of the children in urban Nigeria participate in physical activity. The prevalence of overweight and obesity is low but undernutrition is a major nutritional problem among these children.

Effects of a 6-week circuit training intervention on body esteem and body mass index in British primary school children

Research examining the impact of physical activity on children's body image has been limited and equivocal. The current researchers examined the effect of 6-week circuit-based training on body esteem and body mass index (BMI) in 68 British children (34 boys and 34 girls, aged 10-11 years, 16% overweight, 7% obese). The Body Esteem Scale for Children (BES-C) was administered to both the intervention group and control group, pre, post and 6 weeks post the intervention. BMI was directly assessed from height and body mass pre- and post-intervention. The results of this study revealed that, as compared to the control group, participation in 6-week circuit training significantly improved body esteem scores post-intervention. However, these scores were not sustained 6 weeks post-intervention. The improvement in body esteem scores from pre- to post-intervention was greater for girls as compared to boys. Additionally, BMI decreased significantly in the intervention group compared to the control group.

Objectively measured physical activity, physical activity related personality and body mass index in 6- to 10-yr-old children: a cross-sectional study

Background

The prevalence and level of overweight in childhood is rapidly increasing. One potential contributor to the rise in overweight is a decline in physical activity (PA). The purpose of this study was to compare levels and patterns of PA and PA related personality in normal-weight (NW) and overweight (OW) 6- to 10-yr-old children.

Methods

Subjects were grouped into OW (N = 59, BMI = 24.2 ± 4.8 kg/m²) or NW (N = 61, BMI = 15.7 ± 1.5 kg/m²) according to International Obesity Task Force cut-offs. PA was assessed by accelerometry. Parents filled in a questionnaire on PA and sedentary behaviour and PA related personality of their child (born tired, moves slowly, is often tired, lacks energy, avoids physical efforts, prefers watching playing children instead of joining them, is always active, needs to let himself/herself go, has a lot of energy).

Results

NW children spent on average 77 min/day in MVPA, whereas OW children only 57 min/day (p = .001). OW children had fewer 5, 10 and 20 min bouts of MVPA (p = .01). OW and NW children showed identical PA patterns on both week days and weekends, although at different levels. According to parents' report, a greater percentage of OW children was not engaged in any sport (46% versus 23%, chi² = 6.3, p = .01). OW children had a less active personality (p < .001), watched more TV during weekend (p < .01), but no differences were found in outside play or non-active play. BMI of mother and father explained 29% of the variance in children's BMI z-score (p < .001). PA related personality, screen behaviour during weekend and MVPA explained an additional 12% (p < 0.01).

Conclusion

The results of this study demonstrate that NW children spent on average 20 min per day more in MVPA. PA patterns were similar in NW versus OW children, although at different levels. Greatest differences in PA according to weight status were found in the afternoon during after school hours. This is the first study to show distinct PA related personality traits in OW children compared to NW peers.