Investigating the causal effects of physical activity and sedentary behavior on hernia risk: A two-sample Mendelian...

The global prevalence of hernia is increasing, particularly due to the aging population. Although physical activity and sedentary behavior are known to influence various health outcomes, their specific roles in hernia development remain inadequately investigated. This study aimed to systematically assess the causal relationships between physical activity, sedentary behavior, and the risk of hernia development using Mendelian randomization (MR) analysis. We used genome-wide association study data from the UK Biobank and FinnGen Biobank to explore the causal effects of sedentary behavior on hernia risk via 5 distinct MR approaches. To ensure the reliability of our risk models, we performed sensitivity analyses, including Cochran's Q test, MR-Egger intercept analysis, leave-one-out analysis, and funnel plots. Furthermore, we employed multivariable MR analysis to determine the independent causal effects of both physical activity and sedentary behavior. Our findings indicate that moderate-to-vigorous physical activity (MVPA) was significantly associated with an increased risk of inguinal hernia, with an odds ratio of 1.844 (95% confidence interval, 1.181-2.879; P = .007). Associations between sedentary behavior and diaphragmatic or umbilical hernia were inconsistent across methods and were sensitive to pleiotropy; thus, no robust causal relationship was established. Multivariable MR analysis further confirmed the independent and significant causal relationship between MVPA and inguinal hernia, with an odds ratio of 1.901 (95% confidence interval, 1.098-3.291; P = .022). Our study highlights a significant association between MVPA and an increased risk of inguinal hernia, suggesting that physical activity should be carefully considered in preventive strategies for hernias. However, the relationship between sedentary behavior and hernia development warrants further investigation.