Estimation equation of limb lean soft tissue mass in Asian athletes using bioimpedance analysis

The lean soft tissue mass (LSTM) of the limbs is approximately 63% of total skeletal muscle mass. For athletes, measurement of limb LSTM is the basis for rapid estimation of skeletal muscle mass. This study aimed to establish the estimation equation of limb lean soft tissue mass in Asian athletes using bioimpedance analysis (BIA). A total of 198 athletes (121 males, 77 females; mean age 22.04 ± 5.57 years) from different sports in Taiwan were enrolled. A modeling group (MG) of 2/3 (n = 132) of subjects and a validation group (VG) of 1/3 (n = 68) were randomly assigned. Resistance (R) and reactance (Xc) were measured using 50KHz current measurement in whole-body mode. Predictor variables were height, weight, age, gender, Xc, resistance index (RI; RI = h2 / R). Lean soft tissue mass of upper and lower limbs measured by dual-energy X-ray absorptiometry (DXA) was the response variable. Multivariate stepwise regression analysis method was used to establish BIA estimation equations as ArmsLSTMBIA-Asian and LegsLSTMBIA-Asian. Measurement equations performance was confirmed by cross-validation. The established single-frequency BIA estimation equation quickly and accurately measures lean soft tissue mass of the arms and legs of Asian athletes.