| Popis: |
Background: The "neutral" lumbar posture is considered the position least likely to cause low back pain, with errors as little as 2° from the neutral spinal posture substantially decreasing the axial compressive load capacity of the spine. Accurate sensory feedback from, and activation of, appropriate trunk muscles is essential for appreciation and maintenance of the neutral spinal posture. If these muscles are dysfunctional due to low back pain and/or workrelated activity and fatigue, this might impair people’s ability to discriminate the neutral spinal posture. This study investigated whether LBP or a shift of work alters people’s ability to discriminate the neutral low back sitting posture. Methods: Sixty one subjects with, and forty subjects without, a history of LBP were recruited. Each subject’s spinal position sense was assessed before and after a shift of work by an electro-goniometer placed over the lumbar sacral spine. Subjects were blindfolded and instructed to actively locate the neutral low back sitting posture – the "test" position. They were then asked to flex or extend their low back and stop at a random position for 3 seconds, before returning to the neutral low back sitting position; the position they returned to was the "reproduced" position. This procedure was repeated 20 times in total. The absolute error between the "test" position and each "reproduced" position was calculated in degrees. The average mean error was then calculated and compared between the two groups using an independent-samples t test. Results: Data was not normally distributed and therefore log-transformed before analysis. Anti-logged (returning data to original scale) values are also presented. LBP subjects had slightly higher average mean error values before work, showing that they found it more difficult than NLBP subjects to discriminate the neutral low back sitting posture, but the difference was nonsignificant. Conclusions: The ability of people with and without LBP to appreciate the neutral low back sitting posture was similar, both before and after a shift of work. |
