Physical activity, body composition and physical self esteem among children and adolescents

Sammanfattning: The increasing prevalence of overweight and obesity poses a global health problem. Special concern is focused on overweight during youth since it may cause negative impact on health both during childhood, adolescence and later life. Physical activity is a key component in preventing overweight and associated with major health benefits and therefore crucial in youth health. An important personal factor for being physically active is the individual perceived physical self-esteem. Aim The aims of this thesis were to measure physical activity level by means of daily pedometer steps, body composition, expressed as body mass index (BMI) and Bioelectrical Impedance as percent body fat, and individual perceived physical self-esteem. It was also, to test for reliability and validity the Swedish translation of Children and Youth Physical SelfPerception Profile (CY-PSPP). Further, to compare activity and BMI levels between three countries and establish BMI referenced pedometer determined cut points. An additional aim was to evaluate eventual predictors for a healthy lifestyle i.e. highly physically active, normal weighted and a high physical self-esteem in a follow-up group (FUG). Methods During autumn 2000 physical activity level (daily mean steps) was assessed in 892 school children aged 7-14 years in south-eastem Sweden, additionally BMI was calculated and in 501 of these children physical self-esteem was also assessed. Using the same protocol, data was gathered in United States from 711 children and in Australia from 593 children. In Sweden during autumn 2003, a total of 375 adolescents aged 15-18 years were assessed using the same methodology and together with that, percent body fat was measured. Ninety-three of these adolescents, (46 girls), were also measured in 2000 (FUG). Results The results provided baseline information useful as reference data on levels of physical activity, BMI (age 7-18) perceived physical self-esteem (age 10-17) and percent body fat (age 15-18). A drop in physical activity was seen in boys during early adolescents. Physical activity (accumulating daily steps) correlated, in most age groups poor to fair negatively to BMI and poor to fair to physical self-esteem. In boys, there was a poor negative, and in girls, a fair negative correlation between physical self-esteem and BMI. BMI criterionreferenced cut points indicated, for each sex and age group, the optimal median cut point for steps per day for 6-12 year olds to be 12 000 steps per day for girls and 15 000 steps per day for boys. In the FUG the strongest predictor to be highly physically active, maintain a normal BMI and a high physical self-esteem three years later, was for girls increased physical self-esteem and for boys a decreased BMI. Conclusion Instruments used herein, pedometers and the Swedish translation of the CYPSPP, were useful to measure and classify levels of physical activity and perceived physical self-esteem in children and adolescents. With these instruments it was possible to identify individuals "at risk" for physical inactivity and low physical self-esteem. Based on pedometer steps per day, understandable recommendations could be given to professionals in health care and education, parents, children and adolescents and thereby support actions formed to influence healthy habits.