Health-related behaviors, physical fitness, and health-related quality of life in children and adolescents

Laburpena

Background. Health-related quality of life (HRQoL) is a multiple construct, affecting individual, physical, mental, and social well-being. Its maintenance during childhood and adolescence is one of the major public health challenges nowadays. Building a healthy lifestyle during those lifetime periods would help to keep a suitable physical, mental, and social well-being through life having a direct positive impact in children's and adolescents HRQoL. The adherence to health-related behaviors and the improvement of individual attributes contribute to achieve better physical and mental health status, which in turn, could improve overall HRQoL in children's and adolescents. However, previous research in this field is limited, and the possible mechanisms explaining these relationships have not been investigated in children's and adolescents. Purposes. i) To investigate the relationship between health-related behaviors and HRQoL; ii) to analyse the association between physical fitness and HRQoL; iii) to examine the mechanisms that could explain those associations in children and adolescents. Methods. This work employed two different population samples. On one hand, a total of 262 (study I) and 199 (study II) adolescents aged 13.9 ± 0.3 years, and 181 (study IV) aged 15.8 ± 0.3 from DADOS (Deporte, ADOlescencia y Salud) study. On the other hand, 383 children aged 10 ± 0.5 years from The Active West Lancs programme. The variables used were HRQoL as a dependent variable for all the studies, several health-related behaviors (i.e., vigorous physical activity, adherence to the Mediterranean diet, sleep quality, sleep duration, and screen time), physical fitness (i.e., cardiorespiratory fitness, muscular strength, and motor competence) and psychological correlates of physical activity (i.e., self-efficacy and enjoyment) as dependent variables and possible mechanisms influencing associations with HRQoL, respectively. Main findings. The main findings of this work were: study I) adherence to the Mediterranean diet, sleep quality, and sleep duration showed an individual positive association with HRQoL; besides, adolescents that presented good sleep quality and duration and lower screen time reported greater HRQoL; finally, adolescents achieving 3 or more health-related behaviors had higher HRQoL levels; study II) physical fitness at baseline showed a positive association with HRQoL at 24-month follow-up. Both, health-related behaviors and physical fitness components at baseline showed a cumulative positive impact on adolescent's HRQoL at baseline and at 24-month follow-up, respectively; study III) cardiorespiratory fitness at baseline was associated with HRQoL at baseline and at 12-week follow-up in children, and psychological correlates of physical activity (i.e., self-efficacy and enjoyment) acted as mediators in this association; study IV) cardiorespiratory fitness and muscular strength acted as mediators in the association between adherence to the Mediterranean diet and HRQoL in adolescents. Overall conclusion. The adoption of health-related behaviors as well as achieving higher physical fitness may improve children's and adolescents HRQoL. Besides, the study of possible mediators allows us to better understand possible mechanisms influencing the association between health-related behaviors and physical fitness with HRQoL. Childhood and adolescence are lifetime periods characterized by changes and behaviors's adoption which appear to track into adulthood. Therefore, the present Doctoral Thesis represents an important step forward from a public health perspective since its findings could help to develop successful strategies to improve overall children's and adolescents HRQoL.