Association between physical activity energy expenditure and bone mineral density in US adults: A cross-sectional analysis of NHANES 2011-2018

Objectives: Osteoporosis is a global disease characterized by decreased bone mineral density (BMD) and impaired bone metabolism. The Physical Activity Metabolic Equivalent of Task (PA-MET) quantifies energy expenditure during physical activities. This study aims to investigate the relationship between energy expenditure, BMD, and the risk of developing osteoporosis. By exploring how varying levels of physical activity impact BMD, we seek to better understand the role of energy expenditure in osteoporosis prevention and management. Study design: Cross-sectional study. Methods: This was a cross-sectional study that included 6599 adult participants who took part in the National Health and Nutrition Examination Survey (NHANES) from 2011 to March 2018. We used multivariate weighted linear model analysis to reveal the association between PA-MET levels and BMD. Results: Multivariable weighted linear model analysis showed a positive correlation between PA-MET and total BMD. Compared to the lower PA-MET group, the fourth quartile of the PA-MET group had a (3 = 0.02 (95 % CI, 0.01 to 0.03). Similarly, in the analysis with thoracic spine BMD as the outcome, the fourth quartile of the PA- MET group had a (3 = 0.02 (95 % CI, 0.01 to 0.02) compared to the lower PA-MET group. For lumbar spine BMD, the fourth quartile of the PA-MET group had a (3 = 0.02 (95 % CI, 0.01 to 0.03). In the analysis with trunk BMD as the outcome, the fourth quartile of the PA-MET group had a (3 = 0.02 (95 % CI, 0.02 to 0.03) compared to the lower PA-MET group. Conclusions: Our results show that the energy expenditure from physical activity has a positive relationship with BMD, which serves as a protective factor against the risk of osteoporosis.