Arm Elevation Angle and Spinal Curvature in Healthy Adults

Abstract

[Purpose] In this study, we investigated the relationship between arm elevation angle and spinal curvature (thoracic kyphosis and lumbar lordosis) in healthy adults. [Subjects] The subjects were 12 healthy adult males, average age 23.6 ± 5.5 years. [Method] We measured thoracic kyphosis and lumbar lordosis angles with the arms in 5 positions, at the sides, raised at 90, 120, 150° and the maximum elevation, and compared the results of each elevation. [Results] We found that at 150° and maximum elevation the thoracic kyphosis angle showed a significant reduction compared to elevations of 120° or less, and the lumbar lordosis angle was significantly increased compared to arms at the sides. Moreover, this increase in lordosis angle showed a generally linear relation to the arm elevation angle. [Conclusion] The relationship between arm elevation and spinal curvature was one in which the lumbar lordosis angle increased linearly with arm elevation, and at elevations of 150° and above, in addition to lumbar lordosis, thoracic kyphosis decreased significantly, suggesting a mutual contribution from the thoracic and lumbar spines in arm elevation movement.