Objective To determine whether, and to what extent, physical activity interventions affect the overall activity levels of children.Design Systematic review and meta-analysis.Data sources Electronic databases (Embase, Medline, PsycINFO, SPORTDiscus) and reference lists of included studies and of relevant review articles.Study selection Design: randomised controlled trials or controlled clinical trials (cluster and individual) published in peer reviewed journals. Intervention: incorporated a component designed to increase the physical activity of children/adolescents and was at least four weeks in duration. Outcomes: measured whole day physical activity objectively with accelerometers either before or immediately after the end of the intervention period. Data analysisIntervention effects (standardised mean differences) were calculated for total physical activity, time spent in moderate or vigorous physical activity, or both for each study and pooled using a weighted random effects model. Meta-regression explored the heterogeneity of intervention effects in relation to study participants, design, intervention type, and methodological quality.Results Thirty studies (involving 14 326 participants; 6153 with accelerometer measured physical activity) met the inclusion criteria and all were eligible for meta-analysis/meta-regression. The pooled intervention effect across all studies was small to negligible for total physical activity (standardised mean difference 0.12, 95% confidence interval 0.04 to 0.20; P<0.01) and small for moderate or vigorous activity (0.16, 0.08 to 0.24; P<0.001). Meta-regression indicated that the pooled intervention effect did not differ significantly between any of the subgroups (for example, for total physical activity, standardised mean differences were 0.07 for age <10 years and 0.16 for ≥10 years, P=0.19; 0.07 for body mass index across the entire range and 0.22 for exclusively overweight/obese children, P=0.07; 0.12 for study duration ≤6 months and 0.09 for >6 months, P=0.71; 0.15 for home/family based intervention and 0.10 for school based intervention, P=0.53; and 0.09 for higher quality studies and 0.14 for lower quality studies, P=0.52). ConclusionsThis review provides strong evidence that physical activity interventions have had only a small effect (approximately 4 minutes more walking or running per day) on children's overall activity levels. This finding may explain, in part, why such interventions have had limited success in reducing the body mass index or body fat of children. IntroductionPhysical activity is associated with many health benefits, 1-3 but most children fail to meet national recommendations. [4][5][6] Prevention of obesity in particular is thought to be one of the benefits to being more active, and accordingly most interventions aimed at reducing childhood obesity incorporate a physical activity component. Observational studies consistently show that greater activity is associated (r~−0.2) with lower body mass index and girth, 7-11 yet physical activity int...
Obesity is a serious public health concern. More than half of British adults are overweight, and obesity among preschool children has increased by an alarming 70% in the past generation.1 2 We aimed to explore parents' awareness of overweight and obesity in themselves and their children, and their degree of concern about weight. Participants, methods, and resultsWe studied 277 healthy randomly recruited children (mean age 7.4 years) and parents from the EarlyBird study.3 Overweight and obesity were defined as body mass index at least 25 and 30 in adults, and at least 91st and 98th centiles of the UK 1990 body mass index reference curves for children. 4 Before we weighed them, parents completed a written questionnaire asking them to estimate their own and their child's weight on a five point scale ranging from "very underweight" to "very overweight." Responses indicating level of concern about weight were similarly ranked from "very worried about underweight" to "very worried about overweight."Children and parents were significantly heavier than UK norms (table): 52/277 (19%) children, 141/273 (52%) mothers, and 165/230 (72%) fathers were overweight (including obese). Among overweight parents, 40% mothers (45% fathers) judged their own weight "about right" and 27% (61%) were unconcerned about their weight.Only a quarter of parents recognised overweight in their child. Even when obese, 33% mothers (57% fathers) saw their child's weight as "about right." Parents were less likely to identify overweight in sons than daughters: only 27% of overweight or obese boys were classified as at least "a little overweight," compared with 54% of overweight girls (P = 0.01). More mothers than fathers correctly assessed their child's weight (84% v 76%, P = 0.06).Maternal weight status did not affect mothers' awareness of their chidren's weight: 82% of overweight mothers were correct compared with 82% of normal weight mothers (P = 0.50). However, only 74% overweight fathers were correct compared with 85% normal weight fathers (P = 0.08).More than half of the parents of obese children expressed some degree of concern about their child's weight, but only a quarter were even "a little worried" if their child was overweight. Most parents (86%) who were unaware that their child was overweight, were also unconcerned about their child's weight. One in ten parents expressed some concern about underweight in normal weight children.Prevalence of overweight in parents in the highest and lowest socioeconomic groups did not differ-59% in classes I and II were overweight compared with 62% in classes VI, VII, and VIII (P = 0.63; National Statistics Socioeconomic Classification 2001). Neither was there a difference in correct perception of the child's weight between socioeconomic groups (78% v 82%, P = 0.34).
Most excess weight before puberty is gained before 5 years of age. Weight at 5 years of age bears little relation to birth weight but closely predicts weight at 9 years of age. Single measures of current weight are predictive of metabolic health, whereas weight gain within a specific period adds little. A single measure of weight at 5 years of age provides a pointer to future health for the individual. If metabolic status at 9 years of age means future risk, diabetes/cardiovascular prevention strategies might better focus on preschool-aged children, because the die seems to be largely cast by 5 years of age, and a healthy weight early in childhood may be maintained at least into puberty.
Objective To establish in children whether inactivity is the cause of fatness or fatness the cause of inactivity. Design A non-intervention prospective cohort study examining children annually from 7 to 10 years. Baseline versus change to follow-up associations were used to examine the direction of causality. Setting Plymouth, England. Participants 202 children (53% boys, 25% overweight/ obese) recruited from 40 Plymouth primary schools as part of the EarlyBird study. Main outcome measures Physical activity (PA) was measured using Actigraph accelerometers. The children wore the accelerometers for 7 consecutive days at each annual time point. Two components of PA were analysed: the total volume of PA and the time spent at moderate and vigorous intensities. Body fat per cent (BF%) was measured annually by dual energy x ray absorptiometry. Results BF% was predictive of changes in PA over the following 3 years, but PA levels were not predictive of subsequent changes in BF% over the same follow-up period. Accordingly, a 10% higher BF% at age 7 years predicted a relative decrease in daily moderate and vigorous intensities of 4 min from age 7 to 10 years (r=−0.17, p=0.02), yet more PA at 7 years did not predict a relative decrease in BF% between 7 and 10 years (r=−0.01, p=0.8).Conclusions Physical inactivity appears to be the result of fatness rather than its cause. This reverse causality may explain why attempts to tackle childhood obesity by promoting PA have been largely unsuccessful.
OBJECTIVE -Previous reports have predicted greater risk of type 1 diabetes among people who were heavier as young children. The Accelerator Hypothesis predicts earlier onset in heavier people, without necessarily a change in risk, and views type 1 and type 2 diabetes as the same disorder of insulin resistance, set against different genetic backgrounds. Insulin resistance is a function of fat mass, and increasing body weight in the industrialized world has been accompanied by earlier presentation (i.e., acceleration) of type 2 diabetes. We wanted to establish whether increasing body weight was also asociated with the earlier presentation of type 1 diabetes, as the Accelerator Hypothesis would predict.RESEARCH DESIGN AND METHODS -The relationships between fatness and age at diagnosis were examined in context of birth weight, weight change since birth, weight at diagnosis, BMI at diagnosis, and BMI 12 months later in 94 children aged 1-16 years (49 boys and 45 girls) presenting for management of acute-onset type 1 diabetes.RESULTS -BMI standard deviation score (SDS) at diagnosis, weight SDS change since birth, and BMI SDS 12 months later were all inversely related to age at presentation (r ϭ Ϫ0.39 to Ϫ0.40, P Ͻ 0.001). The boys were significantly fatter than the girls (BMI SDS 0.56 vs. Ϫ0.08, respectively; P ϭ 0.006) and presented with diabetes at a significantly younger age (6.74 vs. 8.32 years, respectively; P Ͻ 0.05). The sex difference in age at diagnosis, however, disappeared when corrected for BMI (P ϭ 0.31), suggesting that fatness or something related to it was the responsible factor.CONCLUSIONS -The data are consistent with the hypothesis that the age at presentation of type 1 diabetes is associated with fatness. The implications for prevention of type 1 diabetes may be important. Diabetes Care 26:2865-2870, 2003T he prevalence of diabetes is increasing rapidly in industrialized countries. Although most attention has focused on the increase in type 2 diabetes, there has been a parallel increase in type 1 diabetes, which requires explanation (1). Type 2 diabetes is believed to result from the loss of -cell function in association with insulin resistance (2). The Accelerator Hypothesis regards type 1 diabetes in the same way (3).Awareness of overlap between type 1 and type 2 diabetes is not new. There has long been interest in insulin resistance in type 1 diabetes, although related more to its implications for management and outcome than to its pathogenesis (4 -8). The term "type one-and-a-half" diabetes, referring to the progression in some from type 2 to type 1 diabetes, was coined years ago and remains an area of lively debate (9). In a modern context, the increasing difficulty in distinguishing type 1 from type 2 diabetes in obese young people has given rise to the designation "double diabetes," in which recognition is given to the coexistence of autoimmunity and insulin resistance (10).The insulin resistance that underlies type 2 diabetes seems to result mainly from lifestyle factors: weight increase a...
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