Background Given the increasingly sedentary nature of policing and the subsequent rise in depression rates among police officers, physical inactivity is considered as a risk factor for depression. In contrast, Vigorous Physical Activity (VPA) is preventative against depression, yet this has been limitedly studied in policing. This study primarily aimed to explore the prevalence of depression and examine its association with VPA in the English police force, further stratified by gender. The secondary aims included examining the impact of socio-demographic and lifestyle variables on the prevalence of depression.

Methods A cross-sectional, secondary data-analysis of the Airwave (the largest cohort-dataset for the UK’s police forces) was undertaken using Stata. The descriptive statistics were used to explore the socio-demographic profile of the sample (n=28,465). The multivariate logistic regression models were run to examine the association between depression and VPA, reporting Odds Ratio (OR) with 95% Confidence Interval (CI) at significance level of 5%, while controlling the covariates.

Results The prevalence of depression was 12% in the English police force and 25% of police employees were physically inactive. The multivariate logistic regression analysis revealed that relative to physically inactive participants, those who did VPA for either 4 or 7 days had equally the lowest odds of reporting depression (OR 0.59, 95% CI: 0.51–0.70, p<0.001) (OR 0.59, 95% CI: 0.45–0.77, p<0.001) respectively, suggesting a U-shaped relationship; which was also observed in the gender-stratification analysis. While the odds of reporting depression were significantly lower for men than women, VPA was significantly associated with reducing the odds of reporting depression slightly more in women (OR 0.43, 95% CI: 0.27–0.67, p<0.001) than in men (OR 0.50, 95% CI: 0.33–0.75, p<0.01), indicating women may be more likely to benefit from VPA than men.

Conclusion VPA may significantly reduce the odds of reporting doctor-diagnosed depression in a U-shaped trend. Being physically active for 4 days may be as beneficial against depression as being active for 7 days. VPA may be more protective against depression for policewomen than policemen. Limited by cross-sectional design, the causal pathway between depression and VPA could not be established. Future research warrants longitudinal study design using objectively measured physical activity and clinically measured depression to fully understand their dose-response relationship. The policymakers may use these findings to design physical-activity guidelines for the English police force. The leadership of the English police force is also recommended to augment police officers’ recruitment and annual fitness tests with mental-health assessments.