Study design: Subjective ratings of discomfort were compared between a fixed lumbar support and lumbar support continuous passive motion (CPM) device.
Objective: To compare a fixed lumbar support with a lumbar support CPM device during prolonged sitting.
Summary of background data: To prevent low back pain during prolonged sitting, an inflatable lumbar support CPM has been developed. There are no studies that compare static lumbar support with lumbar CPM using the same pressure in the cushions.
Methods: A total of 31 male volunteers without low back pain sat in the same chair for a 2-hour period on each of 3 consecutive days under 3 randomized test methods: 1, no lumbar support; 2, static lumbar support; and 3, lumbar support CPM. Each subject rated low back pain, stiffness, fatigue, and buttock numbness on a visual analog scale (VAS). Fixed lumbar support and CPM device were compared with a same inflation pressure in the cushion. For 10 subjects, the whole body posture and the pressure distribution changes of the human-seat interface during CPM were evaluated.
Results: Compared with no lumbar support, a significant improvement in VAS scores for low back pain, stiffness, and fatigue was obtained with both static lumbar support and with lumbar support CPM (P < 0.005). A significant (P < 0.005) improvement for buttock numbness was obtained only with lumbar support CPM. There were no statistical differences in all VAS scores between the fixed lumbar support and the CPM device. A forward rotation of the pelvic region was obtained during inflation of the cushion during CPM. Significant differences (P < 0.05) were found between cushion inflation and deflation periods both in contact areas and in the peak pressures at the human-seat interface.
Conclusion: There were no statistical differences in the subjective ratings of discomfort between the fixed lumbar support and the CPM device.