Diagnostic values of abdominal muscles thickness and sterno-costal angle for young adults with rounded shoulders

Objective: The purposes of this study was to evaluate the diagnostic values of abdominal muscles thickness and sterno-costal angle as the quantitative diagnostic indicators for young adults with rounded shoulders. Design: A observational, cross-sectional study. Methods: This study included thirty-three male participants in order to examine the relationship among thoracic kyphosis, sternocostal angle, and abdominal muscle thickness. We used ultrasound imaging to measure the muscle thickness, two gravity-dependent inclinometers to measure the kyphosis angle, and Image J to measure the sterno-costal angle. Results: There was a significant positive correlation between the amount of thoracic kyphosis angle and muscle thickness of the external oblique (EO) on the right side (r=0.931), and on the left side (r=0.432), and the transverse abdominis (TrA) (r=0.649). There was also a significant negative correlation between the thoracic kyphosis angle and the sterno-costal angle at the right side (r=−0.942) and at the left side (r=−0.860). There was a significant positive relationship with muscle thickness of the EO and TrA on the right side with the thoracic kyphosis angle, and was significant negative relationship with the sterno-costal angle on both sides. Conclusions: The results of the study suggest that the thoracic kyphosis angle is related to muscle thickness of the EO and TrA on the dominant side and the sterno-costal angle. We also suggest that future studies are needed to determine how strengthening the abdominal muscles may contribute to preventing excessive thoracic kyphosis in young adults.