300 Section - Comparison of Lumbar Lordotic Curvature Preservation During Sitting Between Patients With Low Back Pain and Healthy Adults Using Inertial Sensors

Low back pain (LBP) is associated with reduced lumbar lordotic curvature (LLC), but how LLC behaves over time during prolonged sitting in patients with LBP versus healthy adults is unclear. Using inertial sensors, we examined LLC during several sitting conditions and compared patterns between patients with LBP and healthy controls.

Design:

Patients with LBP completed seven 3-minute sitting conditions (Upright/Usual, Office chair/Stool, Keyboard/Mouse/Writing). Two wireless inertial sensors were placed over T12 and S2 to estimate the lumbar lordotic angle (LLA). Three metrics were extracted: time-averaged LLA (LLAavg); within-trial drift from the starting (LLAdrift), reflecting temporal “slumping”; and deviation from an upright reference (LLAdev), quantifying posture relative to each participant’s baseline. Outcomes were compared within the LBP group and between the LBP group and 29 healthy adults from our previous study using same protocol.

Results:

27 LBP patients and 29 healthy adults were analyzed. Within the LBP group, Upright sitting produced greater lordosis than Usual sitting (p< 0.001); Office chair was more lordotic than Stool (p< 0.001); and Keyboard was more lordotic than Mouse and Writing (p< 0.05). LLAdrift did not differ significantly across conditions. Between groups, baseline lordosis was slightly larger in healthy adults than in patients with LBP (13.4° vs 9.8°), and absolute angles (LLAavg) showed mixed, non-significant differences. In contrast, LLAdev was consistently larger in the LBP group, indicating that, relative to their own baseline, patients sat less flexed in all conditions, with significant differences in Office sitting (−0.8° vs +7.6°, p< 0.05).

Conclusion:

Sitting conditions (instruction, chair, task) strongly influence LLC in patients with LBP, following patterns similar to healthy controls. Although baseline lordosis was slightly greater in healthy adults, patients with LBP showed smaller flexion deviations from their upright reference across sitting conditions. These findings may reflect a pain-related protective strategy in LBP patients.