Association between muscle strength and mass and bone mineral density in the US general population: data from NHANES 1999–2002

Purpose It is known that muscle strength and muscle mass play a crucial role in maintaining bone mineral density (BMD). Despite this, there are uncertainties about how muscle mass, lower extremity muscular strength, and BMD are related. We examined the impact of lower extremity muscle strength and mass on BMD in the general American population using cross-sectional analysis. Methods In the study, we extracted 2165 individuals from the National Health and Nutrition Examination Survey 1999–2002. Multivariate logistic regression models were used to examine the association between muscle strength, muscle mass, and BMD. Fitted smoothing curves and generalized additive models were also performed. To ensure data stability and avoid confounding factors, subgroup analysis was also conducted on gender and race/ethnicity. Results After full adjustment for potential confounders, significant positive associations were detected between peak force (PF) [0.167 (0.084, 0.249) P < 0.001], appendicular skeletal muscle index (ASMI) [0.029 (0.022, 0.036) P < 0.001], and lumbar spine BMD. A positive correlation was also found between PF, ASMI, and pelvis and total BMD. Following stratification by gender and race/ethnicity, our analyses illustrated a significant correlation between PF and lumbar spine BMD in both men [0.232 (0.130, 0.333) P < 0.001] and women [0.281 (0.142, 0.420) P < 0.001]. This was also seen in non-Hispanic white [0.178 (0.068, 0.288) P = 0.002], but not in non-Hispanic black, Mexican American and other race–ethnicity. Additionally, there was a positive link between ASMI and BMD in both genders in non-Hispanic whites, and non-Hispanic blacks, but not in any other racial group. Conclusion PF and ASMI were positively associated with BMD in American adults. In the future, the findings reported here may have profound implications for public health in terms of osteopenia and osteoporosis prevention, early diagnosis, and treatment.