The association between accelerometer-measured physical activity and symptoms of depression and anxiety in children and adolescents: a systematic review and meta-analysis

• This systematic review included 30 studies involving 40,334 children and adolescents aged 5-18 years and revealed substantial variability in accelerometer data collection and processing methods across studies, including 11 different device models, 4 wear locations, 6 epoch lengths, 4 intensity thresholds units, 5 valid day definitions, and 7 non-wear criteria, as well as 17 questionnaires used to assess depression and anxiety. • Meta-analysis results showed that moderate-to-vigorous, total, and light physical activity were associated with reduced depression and anxiety in youth, while epoch length and accelerometer wear location may affect the magnitude of this relationship. The findings remained consistent across sensitivity analyses, and no evidence of publication bias was detected. • Of the 30 studies assessed for risk of bias, 2 were rated as good quality, 22 as fair quality, and 6 as poor quality. The main quality problems were the lack of sample size justification, or insufficient reporting of uniform selection criteria.