Objective To synthesise reviews investigating physical activity and depression, anxiety, self-esteem and cognitive functioning in children and adolescents and to assess the association between sedentary behaviour and mental health by performing a brief review. Methods Searches were performed in 2010. Inclusion criteria specified review articles reporting chronic physical activity and at least one mental health outcome that included depression, anxiety/stress, self-esteem and cognitive functioning in children or adolescents. Results Four review articles reported evidence concerning depression, four for anxiety, three for self-esteem and seven for cognitive functioning. Nine primary studies assessed associations between sedentary behaviour and mental health. Physical activity has potentially beneficial effects for reduced depression, but the evidence base is limited. Intervention designs are low in quality, and many reviews include cross-sectional studies. Physical activity interventions have been shown to have a small beneficial effect for reduced anxiety, but the evidence base is limited. Physical activity can lead to improvements in self-esteem, at least in the short term. However, there is a paucity of good quality research. Reviews on physical activity and cognitive functioning have provided evidence that routine physical activity can be associated with improved cognitive performance and academic achievement, but these associations are usually small and inconsistent. Primary studies showed consistent negative associations between mental health and sedentary behaviour. Conclusions Association between physical activity and mental health in young people is evident, but research designs are often weak and effects are small to moderate. Evidence shows small but consistent associations between sedentary screen time and poorer mental health.

CONTEXT: Physical activity can improve cognitive and mental health, but the underlying mechanisms have not been established. OBJECTIVE: To present a conceptual model explaining the mechanisms for the effect of physical activity on cognitive and mental health in young people and to conduct a systematic review of the evidence. DATA SOURCES: Six electronic databases (PubMed, PsycINFO, SCOPUS, Ovid Medline, SportDiscus, and Embase) were used. STUDY SELECTION: School-, home-, or community-based physical activity intervention or laboratory-based exercise interventions were assessed. Studies were eligible if they reported statistical analyses of changes in the following: (1) cognition or mental health; and (2) neurobiological, psychosocial, and behavioral mechanisms. DATA EXTRACTION: Data relating to methods, assessment period, participant characteristics, intervention type, setting, and facilitator/delivery were extracted. RESULTS: Twenty-five articles reporting results from 22 studies were included. Mechanisms studied were neurobiological (6 studies), psychosocial (18 studies), and behavioral (2 studies). Significant changes in at least 1 potential neurobiological mechanism were reported in 5 studies, and significant effects for at least 1 cognitive outcome were also found in 5 studies. One of 2 studies reported a significant effect for self-regulation, but neither study reported a significant impact on mental health. LIMITATIONS: Small number of studies and high levels of study heterogeneity. CONCLUSIONS: The strongest evidence was found for improvements in physical self-perceptions, which accompanied enhanced self-esteem in the majority of studies measuring these outcomes. Few studies examined neurobiological and behavioral mechanisms, and we were unable to draw conclusions regarding their role in enhancing cognitive and mental health.

The aim of the present study was to examine relations between behavior, intentions, attitudes, subjective norms, perceived behavioral control, self-efficacy, and past behavior across studies using the Theories of Reasoned Action (TRA) and Planned Behavior (TPB) in a physical activity context. Meta-analytic techniques were used to correct the correlations between the TRA/TPB constructs for statistical artifacts across 72 studies, and path analyses were conducted to examine the pattern of relationships among the variables. Results demonstrated that the TRA and TPB both exhibited good fit with the corrected correlation matrices, but the TPB accounted for more variance in physical activity intentions and behavior. In addition, self-efficacy explained unique variance in intention, and the inclusion of past behavior in the model resulted in the attenuation of the intention-behavior, attitude-intention, self-efficacy-intention, and self-efficacy-behavior relationships. There was some evidence that the study relationships were moderated by attitude-intention strength and age, but there was a lack of homogeneity in the moderator groups. It was concluded that the major relationships of the TRA/TPB were supported in this quantitative integration of the physical activity literature, and the inclusion of self-efficacy and past behavior are important additions to the model.

Objective To identify the optimal dose and modality of exercise for treating major depressive disorder, compared with psychotherapy, antidepressants, and control conditions. Design Systematic review and network meta-analysis. Methods Screening, data extraction, coding, and risk of bias assessment were performed independently and in duplicate. Bayesian arm based, multilevel network meta-analyses were performed for the primary analyses. Quality of the evidence for each arm was graded using the confidence in network meta-analysis (CINeMA) online tool. Data sources Cochrane Library, Medline, Embase, SPORTDiscus, and PsycINFO databases. Eligibility criteria for selecting studies Any randomised trial with exercise arms for participants meeting clinical cut-offs for major depression. Results 218 unique studies with a total of 495 arms and 14 170 participants were included. Compared with active controls (eg, usual care, placebo tablet), moderate reductions in depression were found for walking or jogging (n=1210, κ=51, Hedges’ g −0.62, 95% credible interval −0.80 to −0.45), yoga (n=1047, κ=33, g −0.55, −0.73 to −0.36), strength training (n=643, κ=22, g −0.49, −0.69 to −0.29), mixed aerobic exercises (n=1286, κ=51, g −0.43, −0.61 to −0.24), and tai chi or qigong (n=343, κ=12, g −0.42, −0.65 to −0.21). The effects of exercise were proportional to the intensity prescribed. Strength training and yoga appeared to be the most acceptable modalities. Results appeared robust to publication bias, but only one study met the Cochrane criteria for low risk of bias. As a result, confidence in accordance with CINeMA was low for walking or jogging and very low for other treatments. Conclusions Exercise is an effective treatment for depression, with walking or jogging, yoga, and strength training more effective than other exercises, particularly when intense. Yoga and strength training were well tolerated compared with other treatments. Exercise appeared equally effective for people with and without comorbidities and with different baseline levels of depression. To mitigate expectancy effects, future studies could aim to blind participants and staff. These forms of exercise could be considered alongside psychotherapy and antidepressants as core treatments for depression. Systematic review registration PROSPERO CRD42018118040.