Growth change in thickness of lateral abdominal muscle during adolescence using allometric analysis

Abstract

The purpose of this study was to examine the relative growth of muscle thickness in the lateral ab dominal muscle groups of junior high school students as well as the differences in growth patterns between the three individual muscles. The subjects were 191 junior high school students from a local club team and the right external oblique; EO, internal oblique; IO and transversus abdominis; TrA muscle thicknesses were measured us ing an ultrasound imaging device. The height and these parameters were plotted on a logarithmic graph to obtain the allometric equation y = bx ^a . EO and IO were represented by three-phase straight lines with two inflection points, EOʼs allometry coefficients being 2.58, 1.56, and 2.76, and the inflection points being 142.0 cm and 171.3 cm. IOʼs allometry coefficients were 0.82, 2.05, and 4.55, and its inflection points were 157.4 cm and 170.4 cm. TrA was depicted as two-phase straight lines with allometry coefficients of ­1.53 and 1.56, with the inflection point of 145.3 cm. This suggests that TrA which has a stabilizing effect on the trunk, grows early.