Approximate surface development of the left side half-trunk by a free-formed model

The approximate surface development, skin length, and surface area of the left side of the trunk of 51 female students were compared with regard to static and stretched postures. The data for each subject were obtained from geometrical models generated by moiré topography with a computer. When the chest was stretched, the anterior surface, the shoulder line, and the arm-base line were transformed from concave to convex, and a gap oriented toward the nipple widened out. The skin elongated vertically and transversely, except at the side of the waistline, where the skin contracted. The area at the top of the trunk decreased about 25%, while the other parts of the trunk increased 8-15%. The total anterior area was 1.20 m2 for the static posture and 1.29 m2 for the stretched posture. When the posterior surface was stretched, the shoulder line changed from convex to concave, the side line from quasi-straight to concave, and gaps oriented toward the chest line disappeared. The skin elongated most at the infrascapular region (20-35%), while the neck base line contracted (-11%). The center of the back and the lower arm base areas enlarged the most (25%) and the lumbar area enlarged the least (12%). The total posterior area was 1.26 m2 in the static posture and 1.37 m2 in the back-stretched posture. In conclusion, the back skin elongated and enlarged more when stretched than the frontal skin.