Background: Positive emotions help children and adolescents develop good personalities and interpersonal relationships. Evidence shows that participation in physical activity is associated with positive emotions in young people. However, there is still a lack of studies on the effects of physical activity on positive emotions in children and adolescents. Objective: The purpose of this systematic review and meta-analysis was to examine the effects of physical activity on positive emotions in children and adolescents. Methods: Online databases (Scopus, PubMed, Web of Science, EBSCOhost, and APA PsycInfo) were searched from inception to August 2022. Result: A total of 24 articles were eventually included representing 3907 participants from 14 different countries. Overall, the effect of physical activity interventions on positive emotions was significant. The studies revealed that positive emotions were statistically better in the physical activity participation group than in the control group without physical activity (SMD = 0.62, 95% CI: (0.24, 1.01), (p < 0.01). Based on subgroup analyses, we found that participation in aerobic exercise for 30–60 min in adolescents aged ≥12 years had a more significant intervention effect on positive emotions. Conclusion: These findings indicate that the moods of children and adolescents who participate in physical activity significantly improved compared with the moods of those who do not participate in physical activity. The age, exercise type, and exercise duration of adolescents are important factors influencing the positive emotions resulting from physical activity interventions.

Objectives: To evaluate the effect of different exercise interventions on depressive symptoms in children and adolescents. Methods: Randomized controlled trials (RCT) published until May 2023 were screened in four databases. The Cochrane collaboration tool was used to assess the risk of bias for quality evaluation. Stata 16.0 software was used for both a pairwise meta-analysis and a series of frequentist network meta-analyses (NMA). Results: A total of 35 RCTs and 5393 participants were included. Aerobic exercise had the most significant effect on depressive symptoms (66.2%), followed by group training (62.5%), resistance exercise (59.0%), and aerobic combined with resistance exercise (57.9%). Furthermore, children and adolescents younger than 15 years showed significant improvement in depressive symptoms (SMD=-0.41, 95% CI (-0.63, -0.19), P < 0.01). The study also found a significant improvement in depression among healthy, obesity, and depressed populations (SMD=-0.25, 95% CI (-0.41, -0.08), P < 0.01); SMD=-0.15, 95% CI (-0.31, -0.00), P < 0.01; SMD=-0.75, 95% CI (-1.32, -0.19), P < 0.01). Additionally, 30 min of exercise had a significant effect (SMD=-0.14, 95% CI (-0,81, -0.01), P < 0.01), and 40–50 min of exercise had the best effect (SMD=-0.17, 95% CI (-0,33, -0.02), P < 0.01). Lastly, exercise frequency of three times per week was significant in children and adolescents (SMD=-0.42, 95% CI (-0,66, -0.18), P < 0.01). Conclusion: Exercise significantly improves depressive symptoms in children and adolescents, with aerobic exercise having the most significant effect. A 12-week, three-times-a-week, 40-50-minute exercise intervention was found to be more effective in younger children and adolescents.

Objective: This study aimed to review and provide an informative synthesis of the findings from longitudinal studies that describe the relationship between sedentary behavior and various health outcomes among young adults. Methods: A literature search was conducted in Web of Science, PubMed, APA PsycInfo, MEDLINE, Embase, and the Cochrane Library for articles that examined the association between sedentary behavior and health outcomes among young adults aged 18–34 years. Two reviewers independently examined the articles and performed data extraction and quality assessment. The level of evidence was determined using the best-evidence synthesis. Results: A total of 34 studies were included in the analysis, 18 of which were high-quality studies. On the basis of inconsistency in the findings among studies, insufficient evidence was concluded for sedentary behavior and adiposity indicators, physical fitness, metabolic syndrome/cardiovascular disease risk factors, cognitive function, and mood disorders. Based on one high-quality study, moderate evidence for a negative relationship between sedentary behavior and physical fitness was observed. Conclusions: Given the trend toward increased time in sedentary behaviors and the inconsistent current findings, additional longitudinal studies of high methodologic quality are recommended to clarify the relationships between sedentary behavior and health outcomes among young adults.

Background: Anxiety, depression, and stress are the most common mental health problems in childhood. Exercise interventions in childhood help to promote mental health. Objective: To investigate the relationship between exercise interventions and improvement of negative emotions such as anxiety, depression, and stress in children (5–12 years). Methods: Articles were searched in five electronic databases from their inception to January 2023. The meta-analysis was performed using Stata 16.0. Results: Twenty-three intervention studies included 6830 children. 1) The exercise intervention group was significantly better than the control group in improving negative emotions (Standard Mean Difference SMD=-0.25, 95% Confidence Intervals CI: -0.34 to -0.15, P < 0.01). Exercise intervention improved different kinds of negative emotions: anxiety (SMD=-0.19, 95% CI: -0.33 to -0.06, P < 0.01), depression (SMD=-0.22, 95% CI: -0.43 to -0.01, P < 0.01), and stress (SMD=-0.33, 95% CI: -0.53 to -0.14, P < 0.01); it was most effective at relieving problematic stress. Exercise interventions lasting 20–45 min were most effective in improving children’s negative emotions (SMD=-0.38, 95% CI: -0.56 to -0.20, P < 0.01). An exercise intervention period of 10 weeks was more effective in improving children’s negative mood (SMD=-0.26, 95% CI: -0.34 to -0.17, P = 0.274). Conclusion: Exercise interventions may improve negative emotions such as anxiety, depression, and stress in children. These findings may have clinical implications for children with negative affect. However, these studies showed a large heterogeneity, and the results should be interpreted with caution. Future studies should report the variability of exercise interventions by gender, age group, and type, intensity, and place of exercise.

Objectives: This study employed compositional data analysis to examine the association between 24-hour activity behaviours and emotional and behavioural problems among left-behind children (LBC). Design: Cross-sectional analysis. Setting: The research used a cross-sectional approach to analyse data collected from LBC living in Ningbo, Zhejiang Province, southern China, between February and May 2023. Participants: A total of 275 LBC aged 9–15 years old were recruited. Outcome measures: The measurement of 24-hour activity behaviour, incorporating sleep, sedentary behaviour (SED), light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA), was accomplished using accelerometers. Emotional and behavioural problems were assessed through the application of the Strengths and Difficulties Questionnaire. Compositional data analysis was used to evaluate the potential relationship between the composition of 24-hour activity and emotional and behavioural problems. Results: Changes in allocation, such as transferring time from SED to sleep and LPA, were associated with better internalising (β _sleep =−0.53, 95% CI −0.60 to −0.46; β _LPA =−0.46, 95% CI −0.55 to −0.38) and externalising problems (β _sleep =−0.31, 95% CI −0.39 to −0.22; β _LP =−0.23, 95% CI −0.32 to −0.13). Furthermore, reallocating time from LPA to MVPA was associated with reduced internalising problems (β=−0.40, 95% CI −0.84 to −0.12). Positive associations with prosocial behaviour were observed when the time was reallocated to MVPA from sleep (β=0.81, 95% CI 0.57 to 1.05), SED (β=0.75, 95% CI 0.51 to 0.99) and LPA (β=0.82, 95% CI 0.57 to 1.08). Conclusions: The composition of 24-hour activity behaviours is correlated with emotional and behavioural problems in LBC. The findings indicate that redistributing time from SED to sleep and LPA is linked to improved internalisation and externalisation problem scores. Additionally, the substitution of MVPA for any other behaviours is positively associated with enhanced prosocial behaviours.