| Summary: | 碩士 === 國立陽明大學 === 物理治療暨輔助科技學系 === 99 === Low back pain（LBP）is ubiquitous that almost everyone in all cultures and ethnic groups suffers at some point in the lifetime. Activity of the anterolateral abdominal muscle was found to decrease in LBP sufferers, and this change was thought to be the cause of lumbar instability and poor lumbopelvic control. However, the relationships among abdominal muscle contraction, lumbopelvic control, and low back pain was not clear. Clinicians usually use leg movement to yield different load levels to challenge lumbopelvic stability as well as the performance of abdominal muscles. However, the test lacks quantification standards and the participation of the anterolateral abdominal muscles during different levels of loading was not assured. Knowing how these muscles contribute to lumbar stability during the leg loading test will aid clinicians to better assess and plan treatment strategies for subjects with LBP.
Objectives: The study aimed to investigate: 1. If the contraction ability of the three anterolateral abdominal muscles would change with increasing loads during the leg loading test when the lumbo-pelvic stability was maintained. 2. If the roles of the three anterolateral abdominal muscles were the same during the leg loading test. 3. If the contraction pattern of the the three anterolateral abdominal muscles would differ between those with and without LBP.
Study design: Case-control and cross-sectional study.
Procedures and measurement: 20 subjects with low back pain and 20 asymptomatic control subjects participated in the study. Before testing, all the subjects received abdominal contraction training with ultrasound image feedback and lumbopelvic stability training with lumbopelvic pressure feedback, and then performed leg loading test with single leg lowering to 90˚, 60˚, 45˚, 30˚, and 15˚ of hip flexion. Lumopelvic pressure on the pressure biofeedback unit and the ultrasound image on the anterolateral abdominal wall were collected and analyzed in the above six hip flexion angles.
Data analysis: Means and standard deviations of the variables were calculated. Two-way analysis of variance (ANOVA) with repeated measures was performed to determine if lumbopelvic pressure differed in six hip angles between those with and without LBP during the leg loading test. Three-way ANOVA with repeated measures was applied to examine if contraction ratios differed in six hip angles among three anterolateral abdominal muscles and between two subject groups during the test.
Results and Discussion: There was no between-group difference in lumbopelvic pressure and contraction ratio of internal obliquue abdominis (IO) and external obliquue abdominis (EO) at all hip angles. However, the contraction ratio of transverse abdominis (TrA) was significantly reduced at 45˚, 30˚, and 15˚ of hip flexion in those having LBP. Within-group comparison showed the contraction ratio of TrA was not different across different hip angles in asymptomatic subjects. On the contrary, LBP subjects demonstrated decreased contraction thickness with smaller hip angles. Similar pattern was observed in lumbopelvic pressure, but not contraction pattern of IO and EO, which increased with decreasing hip angles (p<.01). The above results showed that during the leg loading test, TrA in healthy subjects could maintain a constant level of contraction when the lumbopelvic stability was sustained, but IO and EO would increase contraction to adapt to increasing loads. Although individuals with LBP could keep lumbopelvis in a stable condition, their TrA contraction ratio decrease with increasing loading to the spine. This decrease was most significant when the leg was lowered to 45˚, 30˚, and 15˚ of hip flexion.
Conclusion & Clinical Relevance: In leg loading test combined with abdominal draw-in maneuver, TrA was a prime mover and could maintain a constant level of contraction with stable lumbopelvic control. IO and EO were synergists to TrA and increased contraction when the load to the spine increased. The role of TrA was interfered by LBP and showed decreased contraction when spinal loads increased. This information would help clinicians in better assess and plan TrA training strategy for subjects with LBP.
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