Relationship between Bone Mineral Density and Physical Activity Level in the Elderly

Abstract

This study purposed to investigate the relationship between physical activity level and bone mineral density (BMD) in the elderly of Amirkola in northern Iran. This cross-sectional study was part of a proposal to assess the situation of the elderly in Amirkola (AHAP) (Amirkola Health and Ageing Project) conducted on 1113 elderly individuals (616 males and 497 females) in Amirkola city. Physical activity was measured using a standard questionnaire of physical activity in the elderly (Physical Activity Scale for Elderly). Mineral bone mass was measured using dual energy X-ray absorptiometry in the femur neck and lumbar spines, and vitamin D levels were measured in morning blood samples. T-test, ANOVA, Pearson correlation, and linear regression tests were used to analyze data. The mean physical activity of women (118.6±55.5) was higher than that of men (110.3±71.1) (p=0.035). This study found a significant positive relationship between total physical activity and femur bone mineral density (p=0.001 and r=0.101), but this association was not significant in lumbar spines (p=0.597 and r=0.016), though bone mineral density increased in both areas with increased physical activity (p=0.098). A significant inverse relationship between age and physical activity (p=0.001) and between age and bone mineral density (p=0.001) was observed. Analyzing the influencing variables using the linear regression model indicated physical activity, age, and BMI had significant relationships with bone mineral density in the femur, but neither vitamin D nor calcium played a role. Given the positive correlation between bone mineral density and physical activity, it can be concluded that low intensity weight-bearing activities carried out in compliance with safety rules may be suitable for the elderly.