Abstract
BACKGROUND: This study aimed to investigate the relationships of lumbar spine-hip discoordination during sit-to-stand (STD) and stand-to-sit (SIT) with pain and functional disability in chronic nonspecific low back pain (CNLBP) patients. METHODS: A cross-sectional observational study was conducted in a biomechanics laboratory of the physical therapy department located at the School of Rehabilitation Sciences, Iran University of Medical Sciences (Tehran-Iran). A total of 16 CNLBP patients (men 9, female 7) aged 18-40 years (mean 31.48) were selected according to our eligibility criteria. Furthermore, ten reflective markers were placed on the spinous processes of T12 and S2, posterior and anterior superior iliac spines, greater trochanters, and lateral epicondyles. The patients were instructed to perform STD and SIT tasks at a preferred speed without using their hands. Relative phase angle was used as an indicator of coordination and was identified as the inverse tangent of angular displacement/angular velocity. Moreover, the relative phase angle between the lumbar spine and right and left hip joints was measured by subtracting the phase angle of the hip joint from the lumbar spine joint. The ratios of the total movements of the lumbar spine to the total movements of the right and left hip joints were also calculated in the sagittal plane. Finally, Pearson correlation coefficients (r) were utilized to assess the association between variables. RESULTS: The results of this study indicated that kinematic parameters of the pain had statistically significant direct relationships with functional disability in CNLBP participants during STD and SIT with r values ranging from 0.57 (Pvalue = 0.021) to 0.85 (Pvalue<0.001) and 0.54 (Pvalue=0.053) to 0.82 (Pvalue<0.001), respectively. CONCLUSION: Out of the results of this study, it could be stated that pain and functional disability play a major role in lumber spine-hip discoordination, and it altered the movement ratio in CNLBP patients during STD and SIT. In clinical practice, clinicians should improve lumber spine-hip discoordination in patients with CNLBP since there is a linear relationship between kinematic parameters of the pain and functional disability in patients with CNLBP.