Can differences in physical activity by socio-economic status in European adolescents be explained by differences in psychosocial correlates? A mediation analysis within the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) study.

OBJECTIVE: Socio-economic status (SES) has been positively associated with physical activity (PA) levels in adolescents. In order to tackle these social inequalities, information is needed about the underlying mechanisms of this association. The present study aimed to investigate the potential mediating role of psychosocial correlates of PA on the relationship between SES and PA in European adolescents. DESIGN: Cross-sectional study testing the mediating role of psychosocial correlates in the SES-PA association using the product-of-coefficients test of MacKinnon. SETTING: Ten European cities in nine different countries, the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) Study. SUBJECTS: Adolescents (n 2780) aged 12·5-17·49 years self-reported on PA (moderate-to-vigorous intensity PA and total PA), SES indicators (education of the mother and Family Affluence Scale) and psychosocial correlates of PA (stage of change, attitudes, awareness, modelling, social support, self-efficacy, benefits, barriers and environmental correlates). RESULTS: SES (Family Affluence Scale) was significantly associated with moderate-to-vigorous intensity PA. According to single-mediator models, this association was significantly mediated by stage of change (t = 3·6, P ≤ 0·001), awareness (t = 2·7, 0·001 < P ≤ 0·01), modelling (t = 4·8, P ≤ 0·001), self-efficacy (t = 2·5, 0·01

Nutritional knowledge in European adolescents: results from the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) study.

OBJECTIVE: To build up sufficient knowledge of a 'healthy diet'. Here, we report on the assessment of nutritional knowledge using a uniform method in a large sample of adolescents across Europe. DESIGN: A cross-sectional study. SETTING: The European multicentre HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) study conducted in 2006-2007 in ten cities in Austria, Belgium, France, Germany, Greece (one inland and one island city), Hungary, Italy, Spain and Sweden. SUBJECTS: A total of 3546 adolescents (aged 12·5-17·5 years) completed a validated nutritional knowledge test (NKT). Socio-economic variables and anthropometric data were considered as potential confounders. RESULTS: NKT scores increased with age and girls had higher scores compared with boys (62% v. 59%; P < 0·0001). Scores were approximately 10% lower in 'immigrant' adolescents or in adolescents with 'immigrant' mothers. Misconceptions with respect to the sugar content in food or in beverages were found. Overall, there was no correlation between BMI values and NKT scores. After categorization according to BMI, scores increased significantly with BMI group only in boys. These differences disappeared after controlling for socio-economic status (SES). Smoking status and educational level of the mother influenced the NKT scores significantly in boys, as well as the educational levels of both parents in girls. CONCLUSIONS: Nutritional knowledge was modest in our sample. Interventions should be focused on the lower SES segments of the population. They should be initiated at a younger age and should be combined with environmental prevention (e.g. healthy meals in school canteens).

Self-reported physical activity in European adolescents: results from the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) study.

OBJECTIVE: To describe self-reported physical activity (PA) patterns in the various domains (school, home, transport, leisure time) and intensity categories (walking, moderate PA, vigorous PA) in European adolescents. Furthermore, self-reported PA patterns were evaluated in relation to gender, age category, weight status category and socio-economic status (SES). DESIGN: Cross-sectional study. SETTING: Ten European cities. SUBJECTS: In total, 3051 adolescents (47·6 % boys, mean age 14·8 (sd 1·2) years) completed an adolescent-adapted version of the validated International Physical Activity Questionnaire. RESULTS: The total sample reported most PA during leisure time (485 min/week) and least PA at home (140 min/week). Boys reported significantly more school-based PA (P < 0·001), leisure-time PA (P = 0·003), vigorous PA (P < 0·001) and total PA (P = 0·002) than girls, while girls reported more home-based PA (P < 0·001) and walking (P = 0·002) than boys. Self-reported PA at school (P < 0·001), moderate PA (P < 0·001), vigorous PA (P < 0·001) and total PA (P < 0·001) were significantly higher in younger age groups than in older groups. Groups based on weight status differed significantly only in leisure-time PA (P = 0·004) and total PA (P = 0·003), while groups based on SES differed in all PA domains and intensities except transport-related PA and total PA. CONCLUSIONS: The total sample of adolescents reported different scores for the different PA domains and intensity categories. Furthermore, patterns were different according the adolescents' gender, age, weight status and SES.