This study aimed to determine the "shape" of the trunk of Japanese elite male gymnasts using a new approach: a homologous body model (HBM) based on geometric morphometrics. The participants included Japanese elite gymnasts (GY; age: 22.8 ± 3.8 years, height: 162.8 ± 5.0 cm, and weight: 59.1 ± 5.5 kg) and non-athletes (NA; age: 22.2 ± 3.8 years, height: 171.5 ± 5.2 cm, and weight: 62.9 ± 9.0 kg). A three-dimensional wholebody line scanner (Hamamatsu Photonics, Inc.) was used to scan the upright standing posture. Body fat was estimated using an air-displacement plethysmography. The HBM was constructed by fitting whole-body laser-scanning polygon data to a generic template model based on anatomical landmarks. Principal component analysis was used to assess body "shapes." The main conclusions of this study are as follows: 1) A total of nine PCs explained 94.4% of shape variability. 2) Horizontal cross-sectional comparisons of GY and NA normalized to body height indicated that GY had larger chest circumferences on the ventral and dorsal sides. 3) Normalized HBM to body height indicated that GY had narrower waist and larger and thicker chest regions. 4) Elite GY who excelled in floor exercises and vault had pronounced regions near their neck and upper trunk, while those who excelled in pommel horses and rings had pronounced chest and waist regions. Body "shape" of the Japanese GY did not differ significantly at the competition level; however, they exhibited characteristics specific to the events in which they excelled.
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