Factors associated with low fitness in adolescents--a mixed methods study.

BACKGROUND: Fitness and physical activity are important for cardiovascular and mental health but activity and fitness levels are declining especially in adolescents and among girls. This study examines clustering of factors associated with low fitness in adolescents in order to best target public health interventions for young people. METHODS: 1147 children were assessed for fitness, had blood samples, anthropometric measures and all data were linked with routine electronic data to examine educational achievement, deprivation and health service usage. Factors associated with fitness were examined using logistic regression, conditional trees and data mining cluster analysis. Focus groups were conducted with children in a deprived school to examine barriers and facilitators to activity for children in a deprived community. RESULTS: Unfit adolescents are more likely to be deprived, female, have obesity in the family and not achieve in education. There were 3 main clusters for risk of future heart disease/diabetes (high cholesterol/insulin); children at low risk (not obese, fit, achieving in education), children 'visibly at risk' (overweight, unfit, many hospital/GP visits) and 'invisibly at risk' (unfit but not overweight, failing in academic achievement). Qualitative findings show barriers to physical activity include cost, poor access to activity, lack of core physical literacy skills and limited family support. CONCLUSIONS: Low fitness in the non-obese child can reveal a hidden group who have high risk factors for heart disease and diabetes but may not be identified as they are normal weight. In deprived communities low fitness is associated with non-achievement in education but in non-deprived communities low fitness is associated with female gender. Interventions need to target deprived families and schools in deprived areas with community wide campaigns.

Effects of a novel school-based cross-curricular physical activity intervention on cardiovascular disease risk factors in 11- to 14-year-olds: the activity knowledge circuit.

PURPOSE: This study investigates cardiovascular disease risk factor response in adolescents following introduction of brisk walking into curriculum lessons. DESIGN: Quasi-experimental. SETTING: School-based. SUBJECTS: An intervention group consisted of 115 (aged 12.4 ± 0.5 y) year eight participants, and 77 (aged 12.1 ± 1.1 y) year seven and year nine participants formed a control. INTERVENTION: An 18-week cross-curricular physical activity intervention was implemented in one secondary school. MEASURES: Adiposity variables, blood pressure, lipids, lipoproteins, glucose, insulin, high-sensitivity C-reactive protein, high-molecular-weight adiponectin, aerobic fitness, physical activity behavior, and diet were assessed preintervention and postintervention. ANALYSIS: Dependent and independent t-tests. RESULTS: Prevalence of elevated waist circumference (9.8% vs. 6.9%), systolic blood pressure (3.3% vs. 0%), triglycerides (2.5% vs. 1.2%), and reduced high density lipoprotein cholesterol (3.7% vs. 2.7%) decreased in the intervention group. Significant improvements in high density lipoprotein cholesterol to total cholesterol ratio (mean ± SD: 2% ± 4% [confidence interval (CI)(0.05)  =  1% to 2%], t(80)  =  -3.5, p  =  .001) and glucose (-.1 ± .4 mmol/L [CI(0.05)  =  -.2% to 0%], t(79)  =  3.2, p  =  .002) were evident for the intervention group. CONCLUSION: The Activity Knowledge Circuit may prove to be a sustainable, effective, and cost-effective strategy to engage schoolchildren in physical activity on a daily basis. A longer-duration intervention is required to fully understand risk factor response in adolescents.

ROC generated thresholds for field-assessed aerobic fitness related to body size and cardiometabolic risk in schoolchildren.

OBJECTIVES: 1. to investigate whether 20 m multi-stage shuttle run performance (20mSRT), an indirect measure of aerobic fitness, could discriminate between healthy and overweight status in 9-10.9 yr old schoolchildren using Receiver Operating Characteristic (ROC) analysis; 2. Investigate if cardiometabolic risk differed by aerobic fitness group by applying the ROC cut point to a second, cross-sectional cohort. DESIGN: Analysis of cross-sectional data. PARTICIPANTS: 16,619 9-10.9 year old participants from SportsLinx project and 300 11-13.9 year old participants from the Welsh Schools Health and Fitness Study. OUTCOME MEASURES: SportsLinx; 20mSRT, body mass index (BMI), waist circumference, subscapular and superilliac skinfold thicknesses. Welsh Schools Health and Fitness Study; 20mSRT performance, waist circumference, and clustered cardiometabolic risk. ANALYSES: Three ROC curve analyses were completed, each using 20mSRT performance with ROC curve 1 related to BMI, curve 2 was related to waist circumference and 3 was related to skinfolds (estimated % body fat). These were repeated for both girls and boys. The mean of the three aerobic fitness thresholds was retained for analysis. The thresholds were subsequently applied to clustered cardiometabolic risk data from the Welsh Schools study to assess whether risk differed by aerobic fitness group. RESULTS: The diagnostic accuracy of the ROC generated thresholds was higher than would be expected by chance (all models AUC >0.7). The mean thresholds were 33 and 25 shuttles for boys and girls respectively. Participants classified as 'fit' had significantly lower cardiometabolic risk scores in comparison to those classed as unfit (p<0.001). CONCLUSION: The use of the ROC generated cut points by health professionals, teachers and coaches may provide the opportunity to apply population level 'risk identification and stratification' processes and plan for "at-risk" children to be referred onto intervention services.

Child fitness and father's BMI are important factors in childhood obesity: a school based cross-sectional study.

BACKGROUND: This study examines obesity and factors associated with obesity in children aged 11-13 years in the UK. METHODS: 1147 children from ten secondary schools participated in a health survey that included blood samples, fitness test and anthropometric measures. Factors associated with obesity were examined using multilevel logistic regression. FINDINGS: Of the children examined (490 male; 657 female) a third were overweight, 1 in 6 had elevated blood pressure, more than 1 in 10 had high cholesterol, 58% consumed more fat than recommended, whilst 37% were classified as unfit. Children in deprived areas had a higher proportion of risk factors; for example, they had higher blood pressure (20% (deprived) compared to 11% (non-deprived), difference: 9.0% (95%CI: 4.7%-13.4%)). Obesity is associated with risk factors for heart disease and diabetes. Maintaining fitness is associated with a reduction in the risk factors for heart disease (high blood pressure and cholesterol) but not on risk factors for diabetes (insulin levels). In order of importance, the main risk factors for childhood obesity are being unfit, having an obese father, and being large at birth. CONCLUSION: The high proportion of children with risk factors suggests future interventions need to focus on community and policy change to shift the population norm rather than targeting the behaviour of high risk individuals. Interventions need to focus on mothers' lifestyle in pregnancy, fathers' health, as well as promoting fitness among children. Obesity was not associated with deprivation. Therefore, strategies should be adopted in both deprived and non deprived areas.

A cross-curricular physical activity intervention to combat cardiovascular disease risk factors in 11-14 year olds: 'activity knowledge circuit'.

BACKGROUND: Cardiovascular disease is the leading cause of mortality worldwide. Risk factors associated with cardiovascular disease have been shown to track from childhood through to adulthood. Previous school-based physical activity interventions have demonstrated modest improvements to cardiovascular disease risk factors by implementing extra-curricular activities or improving current physical education curriculum. Few have attempted to increase physical activity in class-room taught curriculum subjects. This study will outline a school-based cross-curricular physical activity intervention to combat cardiovascular disease risk factors in 11-14 year old children. METHOD/DESIGN: A South Wales Valley school of low socio-economic status has been selected to take part. Participants from year eight (12-13 years) are to be assigned to an intervention group, with maturation-matched participants from years seven (11-12 years) and nine (13-14 years) assigned to a control group. A cross-curricular physical activity intervention will be implemented to increase activity by two hours a week for 18 weeks. Participants will briskly walk 3200 m twice weekly during curriculum lessons (60 minutes duration). With the exception of physical education, all curriculum subjects will participate, with each subject delivering four intervention lessons. The intervention will be performed outdoors and on school premises. An indoor course of equal distance will be used during adverse weather conditions. Cardiovascular disease risk factors will be measured pre- and post-intervention for intervention and control groups. These will take place during physical education lessons and will include measures of stature, mass, waist, hip, and neck circumferences, together with skinfold measure's taken at four sites. Blood pressure will be measured, and fitness status assessed via the 20 m multi-stage fitness test. Questionnaires will be used to determine activity behaviour (physical activity questionnaire for adolescence), diet (seven day food diary) and maturation status. Fasting blood variables will include total cholesterol, low-density lipoprotein cholesterol, high density lipoprotein cholesterol, triglycerides, insulin, glucose, high-sensitivity C-reactive protein, interleukin-6, adiponectin, and fibrinogen. Motivational variables and psychological well-being will be assessed by questionnaire. DISCUSSION: Our study may prove to be a cost effective strategy to increase school time physical activity to combat cardiovascular disease risk factors in children. TRIAL REGISTRATION: [NCT00998478].

Cross sectional study of childhood obesity and prevalence of risk factors for cardiovascular disease and diabetes in children aged 11-13.

BACKGROUND: Childhood obesity levels are rising with estimates suggesting that around one in three children in Western countries are overweight. People from lower socioeconomic status and ethnic minority backgrounds are at higher risk of obesity and subsequent CVD and diabetes. Within this study we examine the prevalence of risk factors for CVD and diabetes (obesity, hypercholesterolemia, hypertension) and examine factors associated with the presence of these risk factors in school children aged 11-13. METHODS AND DESIGN: Participants will be recruited from schools across South Wales. Schools will be selected based on catchment area, recruiting those with high ethnic minority or deprived catchment areas. Data collection will take place during the PE lessons and on school premises. Data will include: anthropometrical variables (height, weight, waist, hip and neck circumferences, skinfold thickness at 4 sites), physiological variables (blood pressure and aerobic fitness (20 metre multi stage fitness test (20 MSFT)), diet (self-reported seven-day food diary), physical activity (Physical Activity Questionnire for Adolescents (PAQ-A), accelerometery) and blood tests (fasting glucose, insulin, lipids, fibrinogen (Fg), adiponectin (high molecular weight), C-reactive protein (CRP) and interleukin-6 (IL-6)). Deprivation at the school level will be measured via information on the number of children receiving free school meals. Townsend deprivation scores will be calculated based on the individual childs postcode and self assigned ethnicity for each participating child will be collected. It is anticipated 800 children will be recruited. Multilevel modeling will be used to examine shared and individual factors associated with obesity, stratified by ethnic background, deprivation level and school. DISCUSSION: This study is part of a larger project which includes interviews with older children regarding health behaviours and analysis of existing cohort studies (Millennium cohort study) for factors associated with childhood obesity. The project will contribute to the evidence base needed to develop multi-dimensional interventions for addressing childhood obesity.