In a recent study published in Scientific Reports Journal , researchers compared the associations of physical and sedentary activities with factors such as body fat percentage and bone mineral density among the United States (US) population.
Correlation between sedentary activity, physical activity, and bone mineral density and fat in the United States: National Health and Nutrition Examination Survey, 2011–2018
Summary We compared the relationship between sedentary activity (SA) and physical activity (PA) with bone mineral density (BMD) and body fat percentage in the United States and found a negative association between SA and BMD and a positive association with body fat percentage. A positive association between PA and BMD and a negative association with body fat percentage. AS and AF are associated with changes in skeletal parameters and body fat percentage, and we aimed to investigate and compare the relationship between AS, AF and bone mineral density (BMD) and body fat percentage in men and women. We evaluated the relationship between PA, PA, and BMD and percent body fat in 9,787 Americans aged 20 to 59 years (mean age 38.28 ± 11.39 years) from NHANES 2011-2018. After adjusting for race/ethnicity, age, alcohol consumption and smoking, body mass index (BMI), total protein, blood calcium, blood uric acid, cholesterol, blood phosphorus, vitamin D, and blood urea nitrogen, AS was negatively associated with spine BMD (β = − 0.0011 95% CI − 0.0020 to − 0.0002, P = 0.022), and SA was positively associated with percent total fat (β = PA se positively associated with lumbar BMD (β = 0.0046, 95% CI: 0.0010 to 0.0082, P = 0.012) and there was a negative association between PA and body fat percentage (β = − 1.177 95% CI − 1.326 to –1.027, P < 0.001). Our results show that physical activity is a key component of maintaining bone health in both men and women and is strongly associated with lower body fat percentages. AS is negatively correlated with bone density and is strongly associated with an increase in body fat percentage. Health policy makers should consider reducing sedentary activity and increasing physical activity by preventing osteoporosis and obesity. |
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Background
Osteoporosis, characterized by reduced bone density and deterioration of bone microstructure and a resulting increased incidence of skeletal fractures, is a growing health burden in the US and worldwide.
The factors that result in decreased bone mineral density are multifaceted and involve substantial changes in nutrition and sex hormones. Other factors, such as physical activity levels, smoking, and dietary intake, also influence the development of osteoporosis with age.
Processes such as homeostasis and bone turnover are influenced by periods of bed rest or reduced gravity, and studies have reported that physical activity or sedentary habits have variable effects on bone density in men and women.
While some findings indicate that physical activity is associated with improvements in hip bone mineral density among men, others report no such correlations in women.
Conversely, some studies also report a negative correlation between sedentary activity and bone mineral density among women. Additionally, physical and sedentary activities are also associated with changes in the percentage of total body fat, but results for different age groups have been inconsistent.
About the study
In the present study, researchers analyzed data from the National Health and Nutrition Examination Survey (NHANES), which conducted multistage sampling to examine the health and nutrition status of the civilian population of the United States. USA
Using data spanning the years between 2011 and 2018, the study excluded participants for whom information was missing on lumbar spine bone density measurements and time spent engaging in sedentary activities.
Data on participants with diseases such as cancer, rheumatoid arthritis, thyroid disease, and liver disease, which could affect bone mineral density, were also excluded. Sedentary lifestyle and physical activity were the independent variables in the analysis, while bone mineral density and percentage of total fat were the dependent variables.
Information on physical activities and sedentary lifestyle was collected through structured questionnaires. It was determined based on the hours dedicated per day to vigorous, moderate or sedentary physical activity, respectively. Dual-energy X-ray absorptiometry measured percent total fat and bone mineral density.
Sociodemographic information was also obtained on age, sex, race and ethnicity, and educational level, as well as data on smoking habits and alcohol consumption. Blood biochemical tests measured levels of cholesterol, calcium, total protein, urea nitrogen, blood phosphorus, vitamin D, and serum uric acid.
Multiple linear regression models were used to evaluate the association between the independent and dependent variables while adjusting for confounding variables.
Results
The results reported that sedentary activity was positively correlated with percentage of total fat, while it showed negative associations with lumbar bone mineral density after adjusting for confounding factors such as age, race and ethnicity, smoking, consumption of alcohol, body mass index and levels of total protein, blood urea nitrogen, blood phosphorus, vitamin D and serum uric acid levels.
Furthermore, physical activity showed a negative association with total body fat and a positive correlation with bone mineral density.
The researchers also discussed how increased sedentary activity could exacerbate bone mineral density loss by reducing sunlight exposure and disrupting homeostasis in the skeletal system.
Other studies have also reported increased parathyroid hormone production due to sedentary behavior, which affects the metabolism of calcium essential for bone formation.
Decreased mechanical stimulation due to sedentary habits is also believed to be related to weakened periosteal attachment and loss of bone density, with lack of physical activity having a direct negative impact on osteogenesis.
The results found that the association between physical activity and bone mineral density was stronger in men than in women, which could potentially be explained by the coupled association between muscle mass and bone remodeling as described by the law of Wolfe bone formation.
Conclusions
Overall, the findings suggested that sedentary habits and lifestyles had a negative impact on bone mineral density and increased total body fat percentage. At the same time, physical activity was related to an increase in bone mineral density and a lower percentage of total fat.
