Lean body mass can predict lung function in underweight and normal weight sedentary female young adults

A previous cross-sectional study found reduced lung function among over weight and obese students in Zanjan city. However, there is no reliable evidence about the respiratory function of underweight and normal weight students. The objective of this study was to evaluate lung function and develop prediction equations in underweight and normal weight female young adults residing in Soltanieh city near Zanjan.

A cross sectional study was conducted on underweight (n=29, mean age=16±0.84 years) and normal weight (n=38, mean age=15.9±0.86 years) sedentary female young adults. Fat mass (FM) was measured by Omron Body Fat Monitor FB-3002. Lean body mass (LBM), waist to hip ratio (WHR), body mass index (BMI) and waist circumference (WC) were calculated. Maximum oxygen uptake was calculated using Queen's College step test. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were recorded, using Spirolab III spirometer. Independent t test, Pearson's correlation test and stepwise linear regression analysis were used for data analysis.

FVC and FEV1 were significantly lower than the reference values in both groups (P<0.05). LBM was significantly correlated with FVC and FEV1 in underweight and normal weight groups (P<0.05). Regression equations were derived to predict FVC and FEV1 using LBM.

This study suggests that dynamic lung functions are poor in underweight and normal weight sedentary female young adults residing in Soltanieh city and LBM plays a significant role in their lung function.