Objective: The purpose of this study is to compare the abdominal muscles thickness change at alteration in seated stability between healthy and non–specific chronic low back pain male subjects.
Materials & Methods: In this case–control study, twenty non–specific chronic low back pain male patients whom had refered to physiotherapy clinics of university of Social Welfare and Rehabilitation Sciences and twenty healthy men were selected conveniently and simply. The thickness of Transverse Abdominis, Internal Oblique, External Oblique and Rectus Abdominis muscles of right side were measured with B mode ultrasonography (7. 5 MHz linear head) in supine lying (Position 1) , relaxed sitting on a chair (Position 2) , relaxed sitting on a gym ball (Position 3) and sitting on a gym ball lifting the left foot off the floor (Position 4). Measurement were taken at the end of both inspiration and expiration. Data were analyzied by Paired T and Independent T tests.
Results: Transverse Abdominis and Internal Oblique at all of position and Rectus Abdominis only at position 4 were thicker at the end of expiration in both healthy and patient groups (P<0.001). At the both status of inspiration and expirtion, there were significant differences in both groups in thickness change of Transvers Abdominis, Internal Oblique and Rectus Abdominis muscles between position 3 in comparison with position 2,position 4 with position 2 and position 4 with position 3 (P<0.001). Also there were significan differences in thickness change of External Oblique muscle between position 4 with position 2 and position 4 with position 3 in both groups (P<0.001). There were smaller increase in thickness of Transvers Abdominis in patients than healthy group (P<0.001) and smaller increase in thickness of Rectus Abdominis in healthy men than patient group (P=0.01).
Conclusion: Abdominal muscles respond to postural changes and these muscles are automatically targeted by decreasing the seated stability. In non–specific chronic low back pain patients, activity of Transvers Abdominis was decreased and activity of Rectus Abdominis was increased.