Influences on bone mineral density among adults with mobility Limitations: Results from a national survey.

Background: Risk factors for low bone mineral density (BMD) are widely recognized in the general population; however, influences on BMD in people with mobility limitations is not well understood.

Objective: To examine factors that influence BMD in US adults with mobility limitations, including demographic, anthropometric, and physical activity measures.

Methods: Cross-sectional analysis of NHANES 2013-2018 data, including 421 adults aged ≥20 years with self-reported walking difficulties. Risk factors for low bone mineral density were used including physical activity. Physical activity was assessed using the Global Physical Activity Questionnaire and recoded as meeting or not meeting the guidelines. Total BMD was measured with a dual-energy X-ray absorptiometry scan. Multiple linear regression was used to assess for differences in total BMD.

Results: BMD was significantly higher for males versus females (p < .001), Non-Hispanic blacks versus Non-Hispanic whites (p = .004), individuals who were overweight or obese compared to a people with healthy weights (p = .02, p < .001, respectively). As age increased, BMD decreased. No significant difference in BMD was found between participants meeting physical activity guidelines (1.084 ± 0.012 g/cm²) and those who did not meet guidelines (1.076 ± 0.011 g/cm²; p = .99).

Conclusion: In adults with mobility limitations, traditional demographic and anthropometric risk factors significantly influenced BMD. Calcium intake, vitamin D intake and physical activity guideline adherence were not significant. These findings suggest the need for targeted research to more fully understand bone health determinants in this population.