Background & objective: Skeletal muscle mass represents about 30-40 per cent of the total body weight, and has important roles in function and metabolism. Although newer methods of measuring muscle mass are accurate and sophisticated, there is a need for methods that can be used in low resource settings. Existing methods of predicting muscle mass are based on mid upper arm circumference (MUAC) measurements, sometimes corrected for triceps skinfold fat. The present study was undertaken to develop predictive equations for estimating muscle mass from simple and non-invasive methods such as bioelectrical impedance (BIA) and anthropometric measurements (circumferences and skinfold thickness) in Indian men.
Methods: BIA measurements and anthropometric measurements were carried out on 67 normal, healthy men between the ages of 18 and 45 yr. True muscle mass was measured from 24 h creatinine excretion. Multiple linear regression with step-wise forward selection was used to predict total muscle mass using measurements like height(2)/impedence, height and weight and using arm muscle area (AMA), thigh muscle area (TMA) and calf muscle area (CMA).
Results: The prediction equation for muscle mass (kg) using height(2)/impedance and height was - 12.347+ (0.363 x height(2)/impedance) + (0.122 x height) [R(2) = 0.55; Standard error of estimate (SEE) = 2.58 kg], while the equation using appendicular muscle area was 10.122 + (0.23 x AMA)+ (0.049 x TMA) [R(2) 0.36; SEE 3.07 kg].
Interpretation & conclusion: This study provides prediction equations for estimating muscle mass in healthy Indian males from simple non invasive methods such as BIA and anthropometric measurements such as circumferences and skinfold thickness. Further studies need to be done on a larger sample size and using an external group to validate the equations.