Mechanisms linking physical activity with psychiatric symptoms: a protocol for a systematic review

IntroductionPersistent psychiatric symptomatology during childhood and adolescence predicts vulnerability to experience mental illness in adulthood. Physical activity is well-known to provide mental health benefits across the lifespan. However, the underlying mechanisms linking physical activity and psychiatric symptoms remain underexplored. In this context, we aim to systematically synthesize evidence focused on the mechanisms through which physical activity might reduce psychiatric symptoms across all ages.Methods and analysisWith the aid of a biomedical information specialist, we will develop a systematic search strategy based on the predetermined research question in the following electronic databases: MEDLINE, Embase, Web of Science, Cochrane, and PsycINFO. Two independent reviewers will screen and select studies, extract data, and assess the risk of bias. In case of inability to reach a consensus, a third person will be consulted. We will not apply any language restriction, and we will perform a qualitative synthesis of our findings as we anticipate that studies are scarce and heterogeneous.Ethics and disseminationOnly data that has already been published will be included. Then, ethical approval is not required. Findings will be published in a peer-reviewed journal and presented at conferences. Additionally, we will communicate our findings to healthcare providers and other sections of society (e.g., through regular channels, including social media).PROSPERO registration numberCRD42021239440Strengths and limitations of this studyThis protocol has been designed according to the Preferred Reporting Items for Systematic Reviews and Meta Analyses for Protocols (PRISMA-P) guidelines and guidelines of the Cochrane Effective Practice and Organisation of Care.This protocol presents a cautiously designed search strategy, inclusion and exclusion criteria, and timespan and age-range coverage.A possible limitation is that included studies might be heterogeneous in the study design, data collection methods, and data analysis which might limit the ability to synthesize the results using a meta-analysis.The value of this systematic review depends on the quality and availability of the evidence on the topic.