The purpose of the current investigation was to evaluate the validity of several total body fat-free mass (FFM), muscle mass (TBMM), water (TBW), and appendicular lean mass (ALM) equations in older adults compared to a criterion four-compartment (4C) model and dual-energy X-ray absorptiometry (DXA). Additionally, this investigation examined two body composition-based methods for the classification of sarcopenia. Seventy-four healthy older men (n = 32) and women (n = 42) participated in the investigation (mean ± SD, age = 72 ± 6 years, height =167.5 ± 8.5 cm, mass = 69.49 ± 12.71 kg). Body composition was assessed using bioimpedance analysis (BIA/MFBIA) and spectroscopy (BIS) and compared to a 4C model and DXA. Additionally, relative skeleta...