## 4 Discussion
### Comparison of Coordination Patterns between Groups  
In the current study, a significant difference was observed between healthy and nonspecific CLBP participants in the coordination pattern between the spine and pelvis segments during sit-to-stand and stand-to-sit. This finding is consistent with the results of research by [PERSON] et al. (2021) [19], who found that, in rowers with CLBP, transferring the motion from the distal to the proximal segment stopped lumbopelvic region during the extension phase. Additionally, the transverse coordination patterns of the trunk and pelvis were studied between healthy people and people with CLBP while carrying an anterior load at varied walking speeds. Ten healthy people and ten people with persistent low back pain did an anterior carriage task with a 10% body weight load at 3.5, 4.5, or 5.5 km/h. They found the persistent low back pain group had more anti-phase relative phase than the control group. Walking at 5.5 km/h influenced the intergroup continuous relative phase. They also showed outcomes compared to controls, as people with CLBP reported not being able to get their trunk and pelvis in-phase while walking at 3.5-5.5 km/h [19; 45; 46]. Additionally, the results of the current study were inconsistent with the results of studies by [PERSON] et al. (2013) [47], who found that no significant differences were observed between the groups in terms of the overall range of motion or most of the coordination indices in the lumbar region. The thoracic portion of the spine was more affected by a history of low back pain than the lumbar segment [47]. In addition, kinematic coordination expresses the degrees of freedom that individuals display in performing their movements [48]. These degrees of freedom can deviate from their normal state because of pain or injury and create a new coordination strategy for the individual. Therefore, the difference between spinal and pelvic coordination in people with low back pain compared to healthy people that were observed in this study could be expected.  
In the LT/UT coordination in the sagittal plane, even though there was no significant difference between the two groups during stand-to-sit, the findings of the present study indicated that the antiphase coordination in LT extension and UT flexion with the LT dominancy in the low back pain group was slightly more during sit-to-stand. Compared to healthy people, this is an altered coordination pattern and means that during sit-to-stand, nonspecific CLBP participants try to extend their lower trunk while their upper trunk is in flexion. Extending the lower trunk while the upper trunk is still in flexion position can decrease movement integration and increase the load of UT on the LT. The results of the current study are in line with a previous study that suggested that LBP patients show discoordination between different body segments during sit-to-stand, which leads to pausing in one segment and independent moving in another one [49].  
In PL/LB coordination in the sagittal plane, the findings indicated that the pattern of in-phase coordination in LB extension and pelvis posterior tilt with LB dominancy was more in the healthy group during sit-to-stand and stand-to-sit. Additionally, as it can be seen in Figures 3c and 4c, the rate of in-phase coordination pattern in LB flexion and pelvis anterior tilt in people with low back pain is higher compared to the healthy participants. This finding shows that, since lumbar flexion was lower in healthy people, they showed more extension in the lumbar when returning from flexion. As a result, the in-phase coordination pattern in LB extension and pelvis posterior tilt in healthy people is more frequent. This result is consistent with previous studies that indicated nonspecific CLBP patients show more frequent out-of-phase coordination patterns during sit-to-stand and stand-to-sit [21; 22; 50; 51] (Figure 7).