The Relationship Between Sedentary Behavior, Physical Activity (PA), Body Composition, and Bone Mineral Density (BMD) in Obese Middle-Age and Elderly

Abstract

Background: With the development of the economy and changes in lifestyle, sedentary behavior (SB) and lack of physical activity (PA) have become prevalent trends among middle-aged and elderly individuals, significantly affecting their physical and bone health. Objectives: The present study aimed to explore the relationship between daily SB, PA, body composition, and bone mineral density (BMD) in obese middle-aged and elderly women, providing a theoretical basis for improving bone health and preventing and treating osteoporosis in this demographic. Methods: This study was a descriptive cross-sectional study. One hundred and twelve eligible middle-aged and elderly obese female subjects participated in this study. Dual-energy X-ray absorptiometry (DEXA) was used to quantify body composition and BMD, and a triaxial accelerometer was used to collect data on PA over a seven-day period. The data were analyzed using correlation coefficients and multivariate regression. Results: The present study found that the osteopenia group presented lower body weight, fat mass, fat-free mass (FFM), and body fat percentage than the normal group. The SB and PA duration did not significantly differ between the normal and osteopenia groups at any level (all P > 0.05). No significant correlation was found between SB, PA, and BMD in any region and the whole body. Moderate to vigorous physical activity (MVPA) time has a very weak negative correlation with body fat percentage and fat mass. There exists a positive correlation between regions and whole-body BMD and body weight, fat mass, and FFM to varying degrees. Conclusions: The BMD is influenced by body composition, particularly by body weight and FFM, but it is not directly influenced by SB or PA. It is suggested that the influence of different intensities and forms of resistance exercise intervention on BMD should be investigated in the future to explore the relationship between exercise and BMD and the mechanism behind it.