A deficiency in lumbar muscle blood circulation is considered to be a major risk factor for nonspecific low back pain. The aim of this study was to investigate changes in relative circulation over time in the lumbar multifidus in different sitting positions between subjects with and without LBP.
Ten subjects (mean age, 21.0 years) with low back pain (LBP group) for the past three months and ten healthy subjects (mean age, 21.1 years) without low back pain (non-LBP group) for the past twelve months were recruited. They received a full explanation, and all agreed to participate in this study. Near-infrared spectroscopy (NIRS) was used to non-invasively measure total hemoglobin (Total-Hb), oxygenated hemoglobin (Oxy-Hb), and deoxygenated hemoglobin (Deoxy-Hb) of the lumbar multifidus at the L5-S1 segment. All measurements were obtained in the neutral position, at 30 degrees of trunk flexion, and at 20 degrees of trunk extension while sitting. The subjects were asked to move into either the flexed or extended position from the starting (neutral) position in 3 seconds timed by a metronome and to maintain the positions for 60 seconds. The angles of the flexed and extended positions were measured with goniometer, and self-made devices were used to properly maintain these positions. All participants received education and practice time in order to be able to perform the proper body movements and positions prior to assessment. The measurements were obtained at -3 seconds (neutral position), 0, 30, and 60 seconds in each flexed and extended position while sitting and compared between subjects of the LBP and non-LBP groups.
In flexion, significant interactions were observed with Total-Hb and Deoxy-Hb of lumbar multifidus. There was no significant difference in the changes over time in the LBP group. However, in the non-LBP group, significant decreases were noted in all Total-Hb, Oxy-Hb, and Deoxy-Hb. In extension, significant interactions were observed with the Total-Hb and Oxy-Hb of lumbar multifidus. There were no significant differences in the changes over time in the non-LBP group. However, in the LBP group, significant increases were noted in Total-Hb, Oxy-Hb, and Deoxy-Hb.
The results of this study showed that the intramuscular circulation of lumbar multifidus decreased in the non-LBP group once the trunk started moving into the flexed position on sitting, but there was no change in the LBP group. On the other hand, the intramuscular circulation of lumbar multifidus increased once the trunk started moving into the extended position in the LBP group; however, there was no change in the non-LBP group.
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