Social correlates of sedentary behavior in young people:The UP&DOWN study

Purpose:The aim of the present study was to analyze the associations of youths' sedentary behavior(SB) with parents' and siblings' SB and physical activity(PA),as well as the associations of youths' coparticipation with parents,siblings,and friends in PA and SB with youths' SB.Methods:The sample consisted of 1543 youths(12.02±2.51 years;788 boys) enrolled in the baseline cohort of the UP&DOWN study.SB was assessed by accelerometry and questionnaire.Participants reported the time spent by their parents and siblings watching television,playing videogames,surfing the Internet,sitting/resting,and doing PA.Further,participants reported coparticipation with parents,siblings,and friends in these activities.Linear mixed models,including school and city as random effects,were performed.Results:Parents' television time was positively associated with youths' screen-based SB.Coparticipation with friends in playing videogames(in boys) and in surfing the Internet(in girls) showed a positive association with screen-based SB and a negative association with educational-based SB.Moreover,coparticipation with siblings and friends in PA was inversely associated with accelerometer-based SB in boys and girls.Conclusion:Our results emphasize the important role of social modeling in the development of sedentary lifestyles in youths.Interventions aimed at reducing health risk behaviors in youths could be more effective if they are oriented from a social perspective that involves their families and networks of their closest friends.

Mediation role of cardiorespiratory fitness on the association between fatness and cardiometabolic risk in European adolescents: The HELENA study

Purpose:This study was aimed to analyze the mediation role of cardiorespiratory fitness(CRF)on the association between fatness and cardiometabolic risk scores(CMRs)in European adolescents.Methods:A cross-sectional study was conducted in adolescents(n=525;46%boys;14.1±1.1 years old,mean ±SD)from 10 European cities involved in the Healthy Lifestyle in Europe by Nutrition in Adolescence study.CRF was measured by means of the shuttle run test,while fatness measures included body mass index(BMI),waist to height ratio,and fat mass index estimated from skinfold thicknesses.A clustered CMRs was computed by summing the standardized values of homeostasis model assessment,systolic blood pressure,triglycerides,total cholesterol/highdensity lipoprotein cholesterol ratio,and leptin.Results:Linear regression models indicated that CRF acted as an important and partial mediator in the association between fatness and CMRs in 1217-year-old adolescents(for BMI:coefficients of the indirect role b=0.058(95%confidence interval(95%CI):0.023-0.101),Sobel test z=3.11(10.0%mediation);for waist to height ratio:b=4.279(95%CI:2.242-7.059),z=3.86(11.5%mediation);and for fat mass index:b=0.060(95%CI:0.020-0.106),z=2.85(9.4%mediation);all p<0.01).Conclusion:In adolescents,the association between fatness and CMRs could be partially decreased with improvements to fitness levels;therefore,CRF contribution both in the clinical field and public health could be important to consider and promote in adolescents independently of their fatness levels.