Association between working hours and femoral neck bone mineral density: Results of a national survey

Bone mineral density (BMD) is vital for assessing osteoporosis risk. Although lifestyle and genetic factors influencing BMD have been studied, the impact of occupational factors remains unclear. We explored the association between working hours and femoral neck BMD. Data from 4,518 participants collected from the NHANES database (2017–March 2020) were analyzed. Femoral neck BMD was measured using dual-energy X-ray absorptiometry (DXA). Weekly working hours were categorized as < 35 or ≥ 35. Multivariate regression models adjusted for demographic and lifestyle factors were constructed to examine the relationship between working hours and BMD. The initial analysis revealed no significant association between working hours and BMD (β = 0.01; 95% CI: -0.11, 0.13; p = 0.853). However, after adjusting for covariates, a positive association was found (Model 2: β = 0.23; 95% CI: 0.13, 0.33; p < 0.001; Model 3: β = 0.23; 95% CI: 0.14, 0.33; p < 0.01). Subgroup analyses by sex, age, race, and educational level revealed consistent trends. The positive association between reduced working hours and higher BMD suggests that occupational exposure may affect bone health, while subgroup differences indicated potential interactions with demographic factors. Our findings highlight the need to consider occupational factors in bone health strategies.