Abstract
ObjectivesTo investigate the associations for one-year changes in cardiorespiratory fitness, muscular strength and body mass index, with psychological difficulties status in adolescents. MethodsNorwegian 14-15-year-olds (n = 925) participated in data collection at two time points separated by one year. Psychological difficulties were assessed via the Strengths and Difficulties questionnaire and data from follow-up serve as the dependent variable. Cardiorespiratory fitness (the Andersen-test), muscular strength (Eurofit) and body mass index were measured. Change scores were calculated from the physical fitness variables and serve as independent variables in linear mixed effects models. ResultsThere was no association between change in body mass index and psychological difficulties. Sex and socioeconomic status moderated the association between cardiorespiratory fitness and psychological difficulties. Immigrant status moderated the association between muscular strength and psychological difficulties. Subgroup results indicated inverse associations between change in cardiorespiratory fitness and psychological difficulties among boys (b = −0.009; 95% CI = −0.015 to −0.003; p = .006); change in muscular strength and psychological difficulties among immigrants (b = −1.97; 95% CI = −4.03 to 0.09; p = .061). Subgroup results also indicated an association between change in cardiorespiratory fitness and psychological difficulties among girls in the highest socioeconomic group (b = 0.014; 95% CI = 0.003 to 0.025; p = .014). ConclusionsThe associations for different fitness components were dependent on different moderators. Possibly, this indicates that associations in different subgroups are mediated by different mechanisms. Moderated associations should be addressed in future investigations.
Highlights
Mental health problems are the leading cause of disability among adolescents (Erskine et al, 2015), and because most adult mental dis orders begin in adolescence (Jones, 2013), it is important to investigate viable methods of prevention
All participants are treated as one cohort, but we control for school clus tering and experimental group allocation in the analyses
These results suggest that 100 m increase in cardiorespiratory fitness (CRF) was associated with 8.5% (0.9 points) lower follow-up TDS, relative to boys’ mean values. (10.5 points)
Summary
Mental health problems are the leading cause of disability among adolescents (Erskine et al, 2015), and because most adult mental dis orders begin in adolescence (Jones, 2013), it is important to investigate viable methods of prevention. There is compelling evidence in favor of physical activity (PA) as a preventive measure against mental disorders in adults (Choi et al, 2019), evidence is more inconclusive among adolescents (Biddle, Ciaccioni, Thomas, & Vergeer, 2019). It is unclear how PA influences mental health, Lubans et al (2016) have suggested that the influence may be caused by different neurobiological-, psychosocial- or behavioral mechanisms. The neurobiological mechanism can refer to how aerobic PA can influence structures and functions in various regions of the brain (Matta Mello Portugal et al, 2013). We still know little about the mechanisms and Biddle et al (2019) have called on future research to focus on identifying them
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