Ashley R Cooper

Physical activity levels and patterns of 9- and 15-yr-old European children.

PURPOSE The purpose of this study was to assess physical activity levels and patterns from children participating in the European Youth Heart Study (EYHS). Very limited physical activity data exist that have been collected from representative samples of children and even fewer data collected where physical activity has been measured using objective methods. METHODS Subjects were 2185 children aged 9 and 15 yr from Denmark, Portugal, Estonia, and Norway. Physical activity data were obtained using MTI (formerly CSA) accelerometers. The primary outcome variable was established as the childs activity level (accelerometer counts per minute). Children wore the accelerometer for 3 or 4 d, which included at least 1 weekend day. RESULTS Boys were more active than girls at age 9 (784 +/- 282 vs 649 +/- 204 counts.min-1) and 15 yr (615 +/- 228 vs 491 +/- 163 counts.min-1). With respect to time engaged in moderate-intensity activity, gender differences were apparent at age 9 (192 +/- 66 vs 160 +/- 54 min.d-1) and age 15 (99 +/- 45 vs 73 +/- 32 min.d-1). At age 9, the great majority of boys and girls achieved current health-related physical activity recommendations (97.4% and 97.6%, respectively). At age 15, fewer children achieved the guidelines and gender differences were apparent (boys 81.9% vs girls 62.0%). CONCLUSIONS Accelerometers are a feasible and accurate instrument for use in large epidemiological studies of childrens activity. Boys tend to be more active than girls, and there is a marked reduction in activity over the adolescent years. The great majority of younger children achieve current physical activity recommendations, whereas fewer older children do so-especially older girls.

Commuting to School Are Children Who Walk More Physically Active

BACKGROUND The journey to school is an opportunity for increasing childrens daily physical activity. However, the contribution that active commuting to school makes to overall physical activity is unknown. This study used objective measurement to investigate the physical activity patterns of children by mode of travel to school. METHODS Primary-school children wore an accelerometer programmed to record minute-by-minute physical activity for 7 days and completed a brief questionnaire describing their usual travel to school. The total volume of physical activity and the time spent in activity of at least moderate intensity, as recorded by the accelerometer, was estimated for weekdays and the weekend, and groups of children were compared by mode of transport to school. Data were collected in May/June 2002. RESULTS Of the 114 children (59 boys, 55 girls; aged 10.4+/-0.8 years) who took part in the study, those who walked to school (65%) were significantly more active than those who traveled by car (712.0+/-206.7 vs 629.9+/-207.2 accelerometer counts per minute, p=0.05). Analysis by gender indicated that the major differences in physical activity between travel groups were seen only in boys. Hourly activity patterns demonstrated that boys who walked to school were more active after school and throughout the evening than were car users. CONCLUSIONS In boys, walking to school was associated with higher physical activity after school and during the evening. Active transport may contribute to a more physically active profile, at least for boys, supporting walk-to-school initiatives to increase childrens physical activity.

Improving health through policies that promote active travel: A review of evidence to support integrated health impact assessment

BACKGROUND Substantial policy changes to control obesity, limit chronic disease, and reduce air pollution emissions, including greenhouse gasses, have been recommended. Transportation and planning policies that promote active travel by walking and cycling can contribute to these goals, potentially yielding further co-benefits. Little is known, however, about the interconnections among effects of policies considered, including potential unintended consequences. OBJECTIVES AND METHODS We review available literature regarding health impacts from policies that encourage active travel in the context of developing health impact assessment (HIA) models to help decision-makers propose better solutions for healthy environments. We identify important components of HIA models of modal shifts in active travel in response to transport policies and interventions. RESULTS AND DISCUSSION Policies that increase active travel are likely to generate large individual health benefits through increases in physical activity for active travelers. Smaller, but population-wide benefits could accrue through reductions in air and noise pollution. Depending on conditions of policy implementations, risk tradeoffs are possible for some individuals who shift to active travel and consequently increase inhalation of air pollutants and exposure to traffic injuries. Well-designed policies may enhance health benefits through indirect outcomes such as improved social capital and diet, but these synergies are not sufficiently well understood to allow quantification at this time. CONCLUSION Evaluating impacts of active travel policies is highly complex; however, many associations can be quantified. Identifying health-maximizing policies and conditions requires integrated HIAs.

Low cardiorespiratory fitness is a strong predictor for clustering of cardiovascular disease risk factors in children independent of country, age and sex.

Background and design Few studies have investigated the association between maximal cardiorespiratory capacity (fitness) and the clustered cardiovascular disease (CVD) risk in children and youth from culturally diverse countries. This cross-sectional study examined the association between fitness and clustered CVD risk in children and adolescents from three European countries. Methods Participants were 2845 randomly selected school children aged 9 or 15 years from Portugal (n = 944), Denmark (n = 849) and Estonia (n = 1052). Cardiorespiratory fitness was determined during a maximal test on a cycle ergometer. CVD risk factors selected to assess the degree of clustering were the total cholesterol/high-density lipoprotein cholesterol ratio, plasma triglycerides, insulin resistance (homeostasis model assessment), sum of four skinfolds, and systolic blood pressure. Results There was a strong association between cardiorespiratory fitness and the clustering of CVD risk factors. The odds ratios for clustering in each quartile of fitness, using the quartile with the highest fitness as reference, were 13.0 [95% confidence interval (CI) 8.8-19.1]; 4.8 (95% CI 3.2-7.1) and 2.5 (95% CI 1.6-3.8), respectively, after adjusting for country, age, sex, socio-economic status, pubertal stage, family history of CVD and diabetes. In stratified analyses by age group, sex and country, similar strong patterns were observed. Conclusion Low cardiorespiratory fitness is strongly associated with the clustering of CVD risk factors in children independent of country, age and sex.

Biological cardiovascular risk factors cluster in Danish children and adolescents: the European Youth Heart Study

BACKGROUND The aim of this study was to determine whether the number of participants with multiple coronary heart disease (CHD) risk factors exceeded the number expected from a random distribution. METHODS A cross-sectional study of 1020 randomly selected boys and girls, 9 and 15 years old, was conducted. Risk factors were total cholesterol, HDL-cholesterol, triglyceride, serum insulin, and blood pressure. Physical fitness was assessed from a maximal cycle test and body fat from the sum of four skinfolds. Risk factors selected in the analysis were those related to the metabolic syndrome. RESULTS More participants than expected had four or five CHD risk factors. Four risk factors were found in 3.03 (95% confidence interval (CI): 2.24-4.10) times as many participants as expected from a random distribution and five risk factors were found in 8.70 (95% CI: 4.35-17.4) times as many participants as expected. Fifty (5.4%) had four or five risk factors and in these individuals physical fitness was 1.2 standard deviation (SD) lower and body mass index (BMI) 1.6 SD higher than mean values for the population. CONCLUSION Clustering of risk factors for the metabolic syndrome was found in children and adolescents. Low levels of physical fitness and raised BMI in these individuals indicate that lifestyle factors such as physical activity and diet may influence the development of these unhealthy risk profiles.

Physical Activity and Prevention of Type 2 Diabetes Mellitus

The worldwide prevalence of type 2 diabetes mellitus is increasing at a rapid rate, predominantly because of changes in environmental factors interacting with individual genetic susceptibility to the disease. Data from 20 longitudinal cohort studies present a consistent picture indicating that regular physical activity substantially reduces risk of type 2 diabetes. Adjustment for differences in body mass index between active and inactive groups attenuates the magnitude of risk reduction, but even after adjustment, a high level of physical activity is associated with a 20–30% reduction in diabetes risk. The data indicate that protection from diabetes can be conferred by a range of activities of moderate or vigorous intensity, and that regular light-intensity activity may also be sufficient, although the data for this are less consistent. The risk reduction associated with increased physical activity appears to be greatest in those at increased baseline risk of the disease, such as the obese, those with a positive family history and those with impaired glucose regulation. Data from six large–scale diabetes prevention intervention trials in adults with impaired glucose tolerance or at high risk of cardiovascular disease indicate that increasing moderate physical activity by approximately 150 minutes per week reduces risk of progression to diabetes, with this effect being greater if accompanied by weight loss. However, this level of activity did not prevent all diabetes, with 2–13% of participants per annum who underwent lifestyle intervention still developing the disease. Thus, while 150 minutes per week of moderate activity confers benefits, higher levels of activity may be necessary to maximize diabetes risk reduction in those at high baseline risk of the disease. In contrast, those at low baseline risk of type 2 diabetes, e.g. people with a very low body mass index and no family history of diabetes, will remain at low risk of developing diabetes whether they are active or not. Thus, the amount of physical activity required to confer low risk of diabetes differs according to an individual’s level of baseline risk. Consequently, a ‘one size fits all’ mass–population strategy may not provide the most appropriate approach when designing physical activity guidelines for the prevention of type 2 diabetes. Producing tailored guidelines with the specific aim of reducing risk of diabetes in high–risk populations may provide an alternative approach.

Diet or diet plus physical activity versus usual care in patients with newly diagnosed type 2 diabetes: the Early ACTID randomised controlled trial

BACKGROUND Lifestyle changes soon after diagnosis might improve outcomes in patients with type 2 diabetes mellitus, but no large trials have compared interventions. We investigated the effects of diet and physical activity on blood pressure and glucose concentrations. METHODS We did a randomised, controlled trial in southwest England in adults aged 30-80 years in whom type 2 diabetes had been diagnosed 5-8 months previously. Participants were assigned usual care (initial dietary consultation and follow-up every 6 months; control group), an intensive diet intervention (dietary consultation every 3 months with monthly nurse support), or the latter plus a pedometer-based activity programme, in a 2:5:5 ratio. The primary endpoint was improvement in glycated haemoglobin A(1c)(HbA(1c)) concentration and blood pressure at 6 months. Analysis was done by intention to treat. This study is registered, number ISRCTN92162869. FINDINGS Of 593 eligible individuals, 99 were assigned usual care, 248 the diet regimen, and 246 diet plus activity. Outcome data were available for 587 (99%) and 579 (98%) participants at 6 and 12 months, respectively. At 6 months, glycaemic control had worsened in the control group (mean baseline HbA(1c) percentage 6·72, SD 1·02, and at 6 months 6·86, 1·02) but improved in the diet group (baseline-adjusted difference in percentage of HbA(1c) -0·28%, 95% CI -0·46 to -0·10; p=0·005) and diet plus activity group (-0·33%, -0·51 to -0·14; p<0·001). These differences persisted to 12 months, despite less use of diabetes drugs. Improvements were also seen in bodyweight and insulin resistance between the intervention and control groups. Blood pressure was similar in all groups. INTERPRETATION An intensive diet intervention soon after diagnosis can improve glycaemic control. The addition of an activity intervention conferred no additional benefit. FUNDING Diabetes UK and the UK Department of Health.

What reduction in BMI SDS is required in obese adolescents to improve body composition and cardiometabolic health

Objective To study the impact of body mass index (BMI) SD score (SDS) improvement through lifestyle modification on metabolic risk and body composition over 12 months. Design Prospective cohort study. Setting Hospital outpatient weight management clinic in the UK. Patients 88 adolescents (40 males, 86% Caucasian) of median age 12.4 years (range 9.1–17.4) and mean (SD) BMI SDS 3.23 (0.49). Main outcome measures BMI at baseline and 12 months was adjusted for age and gender providing BMI SDS using British 1990 growth reference data. Body composition was measured by bioimpedance. A standard oral glucose tolerance test (OGTT) examined glucose metabolism. Fasting lipid profiles, high sensitivity C-reactive protein (HsCRP) and blood pressure (BP) were measured. Results Reducing BMI SDS by ≥0.5 achieved significant improvements in important measures of body composition with mean waist circumference SDS reducing by 0.74 units and body fat SDS by 0.60 units, while also leading to significant reductions in key metabolic risk factors (triglycerides (−30%), low-density lipoprotein-cholesterol (−15%), HsCRP (−45%)). A lesser reduction of ≥0.25 improved insulin sensitivity, total cholesterol/high-density lipoprotein ratio and BP. The greater the BMI SDS reduction, the better the improvement seen in insulin sensitivity. The most insulinsensitive individuals at baseline were most likely to achieve BMI SDS changes of ≥0.5 regardless of baseline BMI SDS. Conclusions Improvement in body composition and cardiometabolic risk can be seen with BMI SDS reductions of ≥0.25 in obese adolescents, while greater benefits accrue from losing at least 0.5 BMI SDS. The most insulin-sensitive individuals seem best able to effect these changes.

Patterns of GPS measured time outdoors after school and objective physical activity in English children: the PEACH project

BackgroundObservational studies have shown a positive association between time outdoors and physical activity in children. Time outdoors may be a feasible intervention target to increase the physical activity of youth, but methods are required to accurately measure time spent outdoors in a range of locations and over a sustained period. The Global Positioning System (GPS) provides precise location data and can be used to identify when an individual is outdoors. The aim of this study was to investigate whether GPS data recorded outdoors were associated with objectively measured physical activity.MethodsParticipants were 1010 children (11.0 ± 0.4 years) recruited from 23 urban primary schools in South West England, measured between September 2006 and July 2008. Physical activity was measured by accelerometry (Actigraph GT1M) and children wore a GPS receiver (Garmin Foretrex 201) after school on four weekdays to record time outdoors. Accelerometer and GPS data were recorded at 10 second epochs and were combined to describe patterns of physical activity when both a GPS and accelerometer record were present (outdoors) and when there was accelerometer data only (indoors). ANOVA was used to investigate gender and seasonal differences in the patterns of outdoor and indoor physical activity, and linear regression was used to examine the cross-sectional associations between GPS-measured time outdoors and physical activity.ResultsGPS-measured time outdoors was a significant independent predictor of childrens physical activity after adjustment for potential confounding factors. Physical activity was more than 2.5 fold higher outdoors than indoors (1345.8 ± 907.3 vs 508.9 ± 282.9 counts per minute; F = 783.2, p < .001). Overall, children recorded 41.7 ± 46.1 minutes outdoors between 3.30 pm and 8.30 pm, with more time spent outdoors in the summer months (p < .001). There was no gender difference in time spent outdoors. Physical activity outdoors was higher in the summer than the winter (p < .001), whilst there was no seasonal variation in physical activity indoors.ConclusionsDuration of GPS recording is positively associated with objectively measured physical activity and is sensitive to seasonal differences. Minute by minute patterning of GPS and physical activity data is feasible and may be a useful tool to investigate environmental influences on childrens physical activity and to identify opportunities for intervention.

Physical activity patterns in nonobese and obese children assessed using minute-by-minute accelerometry.

OBJECTIVE:To determine the levels and patterns of physical activity in a sample of obese (≥99th percentile body mass index (BMI)) and nonobese (<99th percentile BMI) children.DESIGN:Cross-sectional study.SETTING:Children were recruited from schools in Bristol and from the childhood obesity clinic, Bristol Royal Hospital for Children. Children were instructed in the use of the accelerometer either while at school or in the clinic, and wore the instrument while carrying out their normal daily activities for 7 days.PARTICIPANTS:A total of133 children (mean age 10.5±0.8 y). In all 11 (16.9%) of the 65 girls and 14 (20.6%) of the 68 boys were classified as obese (above the 99th percentile for BMI and corresponding to projected adult BMI of 30).MAIN OUTCOME MEASURES:Objectively measured physical activity volume, intensity and pattern.RESULTS:Obese children were significantly less physically active overall than their nonobese counterparts (31 844±13 200 vs 41 844±10 430 counts/h; 95% confidence interval 4407 to 15592; P=0.001). Similarly the obese children spent less time in physical activity of moderate or greater intensity than the nonobese children (9.9±3.9 vs 12.9±4.2 min/h; 95% confidence interval 1.15 to 4.80; P=0.002). Hourly patterns of activity indicated a tendency in obese children to be less active than nonobese children at times when activity was more likely to be determined by free choice, particularly outside of school time.CONCLUSIONS:Obese children demonstrated patterns of physical activity that may have contributed to and are likely to sustain their obesity. Minute-by-minute accelerometry is a valuable tool to investigate physical activity patterns in obese children. It can identify periods when intervention to increase activity may be most appropriate and provide an evidence base for specific exercise prescription in primary and secondary care.SPONSORSHIP:Health Education Authority, NHS R& D South–West