Beyond Lean Mass: Body Roundness Index (BRI) Is Independently Associated with Cardiometabolic Health and Physical Performance in Tactical Personnel

Abdominal obesity and low muscle mass increase cardiometabolic disease (CMD) risk. Firefighters and law enforcement officers may have high lean body mass (LBM), but occupational stressors raise their risk of abdominal obesity and CMD. Body roundness index (BRI) measures abdominal fat, but it's unclear whether high LBM can counteract the metabolic damage caused by abdominal adiposity in these personnel. PURPOSE: To evaluate (1) the associations of BRI and LBM with cardiometabolic and physical outcomes and (2) LBM's moderating effect (BRI × LBM interaction) on how abdominal obesity relates to health risks. METHODS: A cross-sectional study involving 158 first responders analyzed LBM via dual-energy X-ray absorptiometry (DXA) and calculated BRI based on height and waist circumference. The outcomes were classified into cardiometabolic markers (such as SBP, MAP, blood glucose, blood lipids, and CRP), aerobic capacity (including treadmill TTE, treadmill TTE normalized to LBM, and VO2max), and muscular performance (push-ups and handgrip strength). A 3-step hierarchical linear regression was used: Step 1 adjusted for potential confounders (i.e., age, sex, and occupation); Step 2 evaluated the independent effects of BRI and LBM, while Step 3 examined their interaction. RESULTS: Model 2 (adding DXA variables) improved the explanation of variance for all 11 variables (p