Upper limit of fat-free mass in humans: A study on Japanese Sumo wrestlers.

If limitations exist in skeletal dimensions, fat-free mass (FFM) might have an upper limit. To explore the upper limit to FFM, 37 professional Japanese Sumo wrestlers, 14 highly trained bodybuilders, and 26 untrained men were investigated for body composition (fat mass and FFM) and cross-sectional areas (CSA) of limb muscles, by hydrodensitometry and ultrasound, respectively. Mean % fat of Sumo wrestlers, bodybuilders, and untrained subjects were, respectively, 26.1%, 10.9%, and 12.1%. Sumo wrestlers had a significantly greater FFM than bodybuilders, who had a greater FFM than the untrained men. Six of the wrestlers had more than 100 kg of FFM, including the largest one of 121.3 kg (stature: 186 cm, mass: 181 kg, %fat: 33.0%). The FFM/stature ratio of elite Sumo wrestlers averaged at 0.61 kg/cm, with the highest 0.66 kg/cm. It is suggested that a FFM/stature ratio of 0.7 kg/cm may be an upper limit in humans. © 1994 Wiley-Liss, Inc.