The effect of adiposity measured by dual-energy X-ray absorptiometry on lung function

Abstract

Respiratory function is impaired in obesity but there are limitations with body mass index and skin-fold thickness in assessing this effect. The present authors hypothesised that the regional distribution of body fat and lean mass, as measured by dual-energy X-ray absorptiometry (DXA), might be more informative than conventional measurements of total body fat.In total, 107 subjects (55 female, 51.4%) aged 20-50 yrs with no respiratory disease were recruited. Respiratory function tests, anthropometric measurements and a DXA scan were performed. Partial correlation and linear regression analyses were used to explore the effect of adiposity and lean body mass on respiratory function.The majority of respiratory function parameters were significantly correlated with DXA and non-DXA measurements of body fat. Neither thoracic nor abdominal fat had a greater effect. There were some differences in the effect of adiposity between the sexes. Respiratory function was negatively associated with lean body mass in females but positively associated in males. This disappeared after adjustment in females but remained in males.The effects of thoracic and abdominal body fat on respiratory function are comparable but cannot be separated from one another.

Lean mass, not fat mass, is associated with lung function in male and female children with asthma

“…Gender differences have also been noted in adults. Recent studies in asthmatic and nonasthmatic adults have reported similar positive associations between lean mass and respiratory function in males only (16,17), whereas negative associations between lean mass and lung function have been reported in female adults with asthma (17).…”

“…Previous studies have indicated that the regional distribution of body composition may be important to respiratory function in asthmatic and nonasthmatic adults (15)(16)(17) and nonasthmatic children (18). In adults, total and regional fat mass have been negatively associated with dynamic and static lung function, with more evident differences in associations between males and females (16,17).…”

“…In adults, total and regional fat mass have been negatively associated with dynamic and static lung function, with more evident differences in associations between males and females (16,17). Increases in dual-energy x-ray absorptiometry (DEXA)-measured thoracic adiposity in adults, with and without asthma, have been associated with poorer respiratory function (16,17), indicating that this region may be an important anthropometric measure. However, its use and reproducibility have not been reported in children.…”

“…Previous studies have indicated that the regional distribution of body composition may be important to respiratory function in asthmatic and nonasthmatic adults (15)(16)(17) and nonasthmatic children (18). In adults, total and regional fat mass have been negatively associated with dynamic and static lung function, with more evident differences in associations between males and females (16,17). Increases in dual-energy x-ray absorptiometry (DEXA)-measured thoracic adiposity in adults, with and without asthma, have been associated with poorer respiratory function (16,17), indicating that this region may be an important anthropometric measure.…”

Predictive Equations for Maximum Respiratory Pressures of Women According to Body Mass

“…This is explained by the adaptation to chronic overload that accompanies obesity. Wannamethee et al 21 and Sutherland et al 22 reported that the increase in respiratory muscle strength is due to the increase in lean mass, hence the importance of the presence of body mass in the predictive equations, particularly for assessing respiratory muscle strength in morbid obesity.…”