| Summary: | 碩士 === 國防醫學院 === 航太醫學研究所 === 95 === Introduction: Low back pain (LBP) is one of most common problems in modern societies. Lumbar disc herniation, one of common pathology of LBP, could exaggerate the clinical presentations, in addition to LBP, such as sciatica, numbness of the lower extremities, and restriction of trunk movement. Active trunk extension exercise training had been advocated as an effective treatment for the patients with chronic LBP (CLBP) beside the traditional passive physical modality intervention. Multi-modes of therapeutic exercise program, however, have made the patients attend uneasily and nonspecifically. Thus specific isokinetic trunk exercise training program was designed at present study to investigate its effect on the muscle strength of trunk and bilateral knees in the patients with LDH. Material & Methods: Thirty-nine subjects with LDH were recruited and classified randomly into two groups, i.e., untrained and trained groups. To alleviate the possible symptom and signs of LDH, passive physical modality, including hot pack, transcutaneous electronic nerve stimulation (TENS), and pelvic traction were applied to both groups five times per week through the treatment period. Isokinetic machine, Biodex system 3, was used to test both groups’ muscle strength of the knees (at three velocities of 0o/s, 60o/s, and 180o/s) and the trunk (isometric contractions at three angles of trunk flexion, i.e., 45o, 60o, and 75o) at the baseline and four weeks later. Trunk training program was designed as followings: 10 reps per set at the velocity of 120o/s for four sets everyday, 3 alternative days per week for four weeks. Meanwhile, to explode the possible mechanism of trunk strength change, the integrated surface electromyography (iEMG) over erector spinae (ES) and multifidus (Ms) and cross-sectional area (CSA) of paraspinal muscle (PA) and psoas major muscles (PS) were measured before and after training. Visual analogue score (VAS) and Oswestry back disability index (ODI) were assessed to reveal the severity of back pain and impairment of physical function separately. Results: Thirty-five subjects completed the whole study, that is, 19 in untrained group and 16 in trained group. Significant increases of peak torque, P < 0.05, were demonstrated at any trunk flexion angle (45o, 60o, and 75o) at either trunk extension (28%, 40%, and 55% increase correspondingly) or flexion contraction (38%, 32%, and 29% increase correspondingly) after trunk training in the trained group. In addition, significant increase of knee strength, sciatica involved-or un-involved side, during extension or flexion exercise at any contraction velocity (0o/s, 60o/s, and 180o/s) was also demonstrated in the trained group after the 4-wk trunk training. No significant change of either trunk or knee performance was seen in the untrained group. Decrease of VAS or ODI scores was demonstrated in the untrained group (P < 0.05, respectively). Significant decrease of ODI (P < 0.05) but not VAS score, though tending to be (p=0.08), was revealed in the trained group. Surface iEMG activity of either ES or Ms was found to be significant increase in the trained but not in the untrained group. However, increase of CSA was only demonstrated significantly in PS but not in PA muscles (about 3.5% increased) in the trained group after trunk training. No change of CSA of both muscles was noted in the untrained group. Conclusion: In the trained group, concurrent significant increase of muscle strength of trunk and bilateral knees, irrespective of sciatica-involved or un-involved, was demonstrated after 4-wk isokinetic training on the trunk only but not on the knees. In the untrained group, who received only passive modality intervention, there was no significant change of either trunk or knee strength after the treatment period. The functional interaction pattern between trunk and knee performance in both groups can be uncovered by the significant correlations between total trunk strength and total knee strength. Increase of iEMG and of CSA of paraspinal muscles after training will account for the increase of trunk strength in the trained subjects. Even though the decrease was demonstrated significantly only in ODI but not VAS scores in the trained group (both scores decreased concurrently in the untrained group), prolonged training study and further testing, e.g., 3-6 months or longer, might be warranted to further unravel the importance of trunk training in the patients with LDH.
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