The Association between Trunk Body Composition and Spinal Bone Mineral Density in Korean Males versus Females: a Farmers' Cohort for Agricultural Work-Related Musculoskeletal Disorders (FARM) Study

The purpose of this study was proposed to identify the association of trunk body composition with spinal bone mineral density (BMD) in Korean male and female farmers. A total of 523 Korean farmers (259 males, 44 premenopausal females, and 220 postmenopausal females) were recruited. Computed tomography scans were acquired at the mid-L4 vertebral level, and total trunk muscle mass (TMM, cm³), back muscle mass (BMM), and abdominal wall muscle mass (AMM), total trunk fat mass (TFM), visceral fat mass (VFM), and subcutaneous fat mass (SFM) were assessed. Spinal BMD (g/cm²) was estimated from dual-energy X-ray absorptiometry at the L4 level. In terms of muscle mass, spinal BMD was significantly correlated with all the components of the trunk muscle mass (r = 0.171-0.360; P < 0.05, P < 0.001) in female farmers, while only with AMM (r = 0.181; P < 0.01) in male farmers. In terms of fat mass, spinal BMD was significantly correlated with all components of the trunk fat mass (r = 0.142-0.424; P < 0.05, P < 0.001) in male and premenopausal female farmers, while only with VFM (r = 0.132; P < 0.05) in postmenopausal females. Adjusted multivariate regression analysis showed that AMM in male and post-menopausal female farmers was closely associated with spinal BMD. There may be positive associations between trunk muscle and fat mass and spinal BMD with sexual dimorphism, and abdominal wall muscle mass was an explanatory variable closely related to spinal BMD in Korean farmers. Registered at the Clinical Research Information Service (CRIS, http://cris.nih.go.kr), number KCT0000829.