Anxiety outcomes after physical activity interventions: meta-analysis findings.

Background: Although the mental health benefits of physical activity (PA) have been documented in numerous primary studies, anxiety outcomes of interventions to increase PA have not been examined through quantitative synthesis.
Objectives: The objective of the study was to integrate extant research about anxiety outcomes from interventions to increase PA among healthy adults.
Method: Through an extensive literature search, published and unpublished PA intervention studies with anxiety outcomes were located. In eligible studies, findings were reported from interventions designed to increase PA delivered to healthy adults without anxiety disorders. Data were coded from primary studies. Random-effects meta-analytic procedures were completed. Exploratory moderator analyses using meta-analysis analysis of variance and regression analogues were conducted to determine if report, methods, sample, or intervention characteristics were associated with differences in anxiety outcomes.
Results: Data were synthesized across 3,289 participants from 19 eligible reports. The overall mean anxiety effect size (d index) for two-group comparisons was .22 with significant heterogeneity (Q = 32.15). With exploratory moderator analyses, larger anxiety improvement effect sizes were found among studies that included larger samples, used random allocation of participants to treatment and control conditions, targeted only PA behavior instead of multiple health behaviors, included supervised exercise (vs. home-based PA), used moderate- or high-intensity instead of low-intensity PA, and suggested participants exercise at a fitness facility (vs. home) following interventions.
Discussion: Some interventions can decrease anxiety symptoms among healthy adults. Exploratory moderator analyses suggest possible directions for future primary research to compare interventions in randomized trials to confirm causal relationships.