Resumo

AUGUSTEMAK DE LIMA, Luiz Rodrigo; RECH, Cassiano Ricardo  e  PETROSKI, Edio Luiz. Use of bioelectrical impedance for the estimation of skeletal muscle mass in elderly men. ALAN [online]. 2008, vol.58, n.4, pp.386-391. ISSN 0004-0622.

The aim of the present study was twofold: a) to determine the agreement between bioelectrical impedance analysis (BIA) and dual energy X-ray absorptiometry (DEXA) for the estimation of skeletal muscle mass (SMM), and b) to analyze the predictive power of anthropometric variables and BIA for the prediction of SMM in the elderly. Sixty elderly men (61 to 80 years) from the southern region of Brazil were studied. Anthropometric variables (body weight and height) were measured, the resistance and hydration of fat-free tissues variables were determined by tetrapolar BIA (BF-310, Biodynamics). A whole body DEXA scan was also performed (Lunar Prodigy DF + 14319 Radiation and 7.52.002 DPX-L software). Differences between methods were analyzed using the t-test, analysis of residues and correlation coefficient. The predictive value of the anthropometric variables and BIA was evaluated by multiple linear regression. BIA overestimated SMM on average by 0.60 kg (sd=1.59) when compared to DEXA, however, no statistical difference was observed (p>0.05). There was a strong correlation between methods (r=0.90; p<0.01). Regression analysis demonstrated that the Ht²/R variable explained 86% of the variation in SMM when adjusted for body weight and age, and this relationship did not depend on body fat, hydration of fat-free tissues or BMI. Thus, BIA as tested here is a valid method for the estimation of SMM in elderly men and its values can be best predicted using the regression model proposed, which included Ht²/R adjusted for body weight and age.

Palavras-chave : Elderly; bioelectrical impedance; densitometry; aging; human skeletal muscle; prediction equation; body composition; men.