Resumen de El comportamiento sedentario en niños y adolescentes: Evaluación, correlatos y relación con la condición física saludable
The overall aims of this PhD Thesis were to (i) develop a questionnaire able to evaluate sedentary behaviors in youth (YSBQ), as well as analyze the test-retest reliability of the questionnaire and its level of criterion validity; (ii) perform a descriptive analysis of sedentary behavior in youth, examining the differences according to sex1 and age; (iii) identify family and socio-demographic correlates of sedentary behavior in youth; (iv) analyze the relationships between the characteristics of the immediate physical environment and the sedentary behaviors in youth; (v) analyze the relationships between the social environment and the sedentary behaviors in youth; (vi) analyze the relationships between the parents restrictions and the sedentary behaviors in youth; and (vii) examine the associations established between sedentary behaviors and other lifestyle factors (moderate-to-vigorous physical activity, diet and sleep) and health-related fitness in youth. The current dissertation has been structured in seven sub-studies so that each sub-study corresponds to one of the overall objectives.
This PhD Thesis was carried out within the UP&DOWN study, a three years longitudinal research study supported by the National Plan for Research, Development and Innovation (R+D+i) from Spanish Ministry of Science and Innovation. The sample included in this dissertation comprises 1.638 healthy children and adolescents (838 boys) aged 8 to 18 years (12.0±2.5) belonging to the first cohort of the UP&DOWN study (year 1). Additionally, were recruited a supplementary sample intended to reliability study of YSBQ. This sample comprises 208 participants (101 boys) aged 10 to 18 years.
Sedentary behavior was assessed by a self-reported questionnaire (YSBQ) and by accelerometry. Family and socio-demographic characteristics, physical and social environment attributes, parental restrictions and variables related to diet quality and sleep time were assessed by self-reported questionnaires. Health-related fitness was measured using the ALPHA battery for youth.
The main findings found in the current dissertation suggest that (i) the YSBQ, developed to evaluate time spent by youth in 12 sedentary behaviors, showed good levels of test-retest reliability and moderate correlations with accelerometer data (validity); (ii) girls accumulate more total sedentary time and report higher time spent in Internet surfing and in social and educational sedentary behaviors, while boys report higher levels of screen time; (iii) TV viewing decreases with age, while total sedentary time and time spent playing videogames, surfing in Internet and in social sedentary behaviors increases with age; (iv) family and socio-demographic variables that show a greater number of relationships with participants’ sedentary behaviors were the school location (rural vs. urban), mother’s and father’s occupation and mother’s BMI; (v) physical environment factors that show a greater number of relationships with youth sedentary behaviors were the density of physical activity materials per person and the density of media equipment per person; (vi) among the behaviors of parents and siblings, parents’ TV viewing show the greatest number of relationships with youth sedentary behaviors; (vii) considering the time shared with family and friends in different behaviors, Internet surfing with friends and engage in physical activity with friends show the greatest number of relationships with youth sedentary behaviors; (viii) boys whose parents impose more restrictions or rules spend less time in screen activities, playing videogames and surfing in Internet; (ix) the number of parental restrictions is positively associated with educational sedentary time in boys and girls; (x) total sedentary time is associated with higher percentages of body fat and worse cardiovascular fitness in boys and girls; (xi) five clústers of lifestyle were identified based on screen time (ST), time spent in other sedentary behaviors (sedentary time – no ST), time in moderate-to-vigorous physical activity (MVPA), quality of Mediterranean diet and sleep time; and (xii) boys and girls classified in “Active” cluster, characterized by high levels of MVPA and low levels of sedentary time – no ST, obtain the healthiest levels in anthropometric and fitness test.
