The lifestyle of our kids (LOOK) project: outline of methods.

This methods paper outlines the overall design of a community-based multidisciplinary longitudinal study with the intent to stimulate interest and communication from scientists and practitioners studying the role of physical activity in preventive medicine. In adults, lack of regular exercise is a major risk factor in the development of chronic degenerative diseases and is a major contributor to obesity, and now we have evidence that many of our children are not sufficiently active to prevent early symptoms of chronic disease. The lifestyle of our kids (LOOK) study investigates how early physical activity contributes to health and development, utilizing a longitudinal design and a cohort of eight hundred and thirty 7-8-year-old (grade 2) school children followed to age 11-12 years (grade 6), their average family income being very close to that of Australia. We will test two hypotheses, that (a) the quantity and quality of physical activity undertaken by primary school children will influence their psychological and physical health and development; (b) compared with existing practices in primary schools, a physical education program administered by visiting specialists will enhance health and development, and lead to a more positive perception of physical activity. To test the first hypothesis we will monitor all children longitudinally over the 4 years. To test the second we will involve an intervention group of 430 children who receive two 50min physical education classes every week from visiting specialists and a control group of 400 who continue with their usual primary school physical education with their class-room teachers. At the end of grades 2, 4, and 6 we will measure several areas of health and development including blood risk factors for chronic disease, cardiovascular structure and function, physical fitness, psychological characteristics and perceptions of physical activity, bone structure and strength, motor control, body composition, nutritional intake, influence of teachers and family, and academic performance.

Discordance of international adiposity classifications in Australian boys and girls - the LOOK study.

BACKGROUND: Various charts based on body mass index (BMI) and per cent body fat (%BF) are used to classify childhood body composition but outcomes may vary. AIM: The study investigated variation in incidences of childhood obesity as depicted by four classification charts. SUBJECTS AND METHODS: BMI and DXA-derived %BF were assessed in 741 children. Incidences of overweight and obesity were compared between two BMI charts and two bioelectrical impedance (BIA)-based %BF charts. RESULTS: The International Obesity Task Force (IOTF)-adopted BMI chart designated 21%, 6% (boys), and 26%, 9% (girls) as overweight and obese, respectively. Corresponding figures using the USA CDC BMI chart were 27%, 11% (boys) and 27%, 12% (girls). Using a USA-derived %BF chart incidences were 17%, 2% (boys) and 21%, 8% (girls) and using a UK-derived %BF chart 51%, 24% (boys) and 53%, 36% (girls). Sensitivity of BMI varied according to the %BF reference chart. CONCLUSIONS: In contrast to the BMI-based charts, there were considerable variations in depicted incidences of obesity between the %BF-based charts. These discordances were considered to result from previously reported variation within and between BIA and DXA %BF assessments underlying the charts. The present study highlights the need for valid, reliable, unchanging BIA and DXA procedures.

Influence of adiposity and physical activity on arterial stiffness in healthy children: the lifestyle of our kids study.

Childhood obesity is increasingly prevalent in the community and is related to adverse cardiovascular outcomes during adulthood. In this study of healthy children, we evaluated the influence of adiposity and physical activity on carotid-femoral pulse wave velocity (PWV), an index of arterial stiffness and a marker of cardiovascular risk in adults. In 573 community-based children (mean age: 10.1+/-0.3 years; 51% boys), we measured body mass index and waist circumference. Percentage body fat was quantitated by dual-energy x-ray absorptiometry. Cardiorespiratory fitness (CRF) and physical activity levels were assessed using a 20-m shuttle run and 7-day pedometer count, respectively. PWV was estimated by applanation tonometry. In univariate analysis, PWV was positively correlated with body mass index (r=0.34), waist circumference (r=0.32), and percentage body fat (r=0.32; P<0.001 for all) and negatively correlated with CRF (r=-0.23; P<0.001) and pedometer count (r=-0.08; P=0.046). In separate multivariable linear regression models, body mass index, waist circumference, and percentage of body fat were independently and positively associated with PWV (P<0.01 for all) after adjusting for age, sex, systolic blood pressure, mean arterial pressure, heart rate, and CRF (P<0.01 for all). The influence of CRF on PWV was attenuated after adjusting for adiposity. In conclusion, increased body mass and adiposity and decreased CRF are associated with arterial stiffening in healthy prepubescent children.