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Objective: To examine the independent association of total and central body fat and cardiorespiratory fitness with markers of insulin resistance after controlling for several potential confounders in European adolescents participating in the HELENA-CSS (Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional) study., Methods: We conducted a cross sectional study (the HELENA-CSS) which comprised 1053 (12.5-17.5 years) adolescents from 10 European cities. Weight, height, waist circumference and skinfold thickness were measured, and body mass index (BMI) was calculated. Cardiorespiratory fitness was measured by the 20-m shuttle run test. Markers of insulin resistance were fasting insulin and glucose, and homeostasis model assessment (HOMA)., Results: HOMA and insulin were positively associated with BMI, skinfolds and waist circumference after controlling for center, age, pubertal status and cardiorespiratory fitness (all P ? 0.01). HOMA and insulin were negatively associated with cardiorespiratory fitness in adolescents with moderate to high levels of total and central body fat (all P ? 0.01)., Conclusions: HOMA and insulin were associated with total and central body fat in European adolescents. Moreover, cardiorespiratory fitness explained a part of the HOMA and insulin variance in those adolescents with moderate to high levels of total and central body fat, and also, to some extent, in those with low to middle fat mass.

Objective: This study was to examine the influence of socioeconomic status on fitness and fatness in Spanish adolescents., Subjects and Methods: A total of 1 795 adolescents (833 boys) aged 12.5-18.5 years from the AVENA study participated in this study. The following physical fitness components were assessed: muscular strength (standing long jump), speed-agility (4 × 10 m shuttle run) and cardiorespiratory fitness (20 m shuttle run). Total and central body fat was assessed using skinfold thickness and waist circumference, respectively. Both parents reported their educational and professional level., Results: Girls with higher paternal educational level and boys with higher either maternal or paternal professional level had higher muscular strength levels (all P<0.05). Speed-agility and cardiorespiratory fitness were not associated with parental educational or professional levels in boys. In contrast, girls with higher paternal educational level or higher parental professional level had higher levels in both fitness components (all P<0.05). A higher maternal educational level was associated with lower total and central body fat in boys (all P<0.05), but not in girls. We observed a small effect size (Cohen's d∼0.2) in most of these associations., Conclusions: Our results suggest modest associations of high socioeconomic status with better fitness and fatness levels in Spanish adolescents. These associations greatly depend on the socioeconomic status and fitness parameters studied.

This review examined recent evidence on associations between objectively measured habitual physical activity and adiposity. A search for observational studies was carried out using several electronic databases from June 2004-June 2008. Of 1 255 potentially eligible papers, 47 papers were included, which described 48 studies. Most studies (41/48; 85%) were cross-sectional and 31/48 (65%) used proxies for adiposity, such as body mass index (BMI) or BMI z-score as the outcome measure. Few studies (10%; 5/48) focused on pre-school children. There was consistent evidence of negative associations between objectively measured physical activity and adiposity: significant negative associations were observed in 38/48 (79%) of studies overall. The present review supports the hypothesis that higher levels of habitual physical activity are protective against child and adolescent obesity. However, prospective longitudinal studies are warranted; there is a need for more research on younger children, and for more 'dose-response' evidence.