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Table 1 Equations used in calculation of Skeletal Muscle Mass (SMM) using bioelectrical impedance analysis. In both equations: Height in cm; Sex 1 = male, 0 = female; Weight in kg; Resistance in Ω; Reactance in Ω

From: Effect of position and exercise on measurement of muscle quantity and quality: towards a standardised pragmatic protocol for clinical practice

Skeletal Muscle Parameter Equation
SMM-Sergi [11] = −3.964 + [0.227 × (height2/resistance)] + (0.095 × weight) + (1.384 × Sex) + (0.064 × reactance)
SMM-Janssen [10] = [(height2/resistance) × 0.401] + (Sex ×  0.3825) + (Age × − 0.071) + 5.102
Phase angle = arctan (reactance/resistance)
“arctan” is the inverse trigonomic function (arc tangent) of the tangent function