Effects and Mechanisms of Specific Trunk Exercises in Low Back Pain

Low back pain affects 80% of Americans at some time during their lives. Although recovery usually occurs within 6 months, there is a 50% recurrence within one year's time. It has long been thought that poor control of trunk muscle may lead to abnormal forces across the spine, which then damage local spinal structures, thus, leading to low back pain. However, the investigators know little about the function of specific trunk muscles in healthy subjects during various activities of daily life. Furthermore, the precise muscle dysfunction associated with low back pain has not been well characterized at all. In addition, the investigators know little about which exercise protocol is most beneficial for particular subgroups of people with low back pain. Thus, the purposes of this study are to learn more about: 1) how trunk muscles are affected by low back pain; 2) which exercises might be most beneficial for people with certain kinds of low back pain; and 3) how these exercises influence trunk muscle function. By having a better understanding of which trunk muscles are affected by low back pain, rehabilitation specialists can design exercise programs and therapeutic interventions that are more specific and more effective.

The stabilization exercise protocol consists of exercises focused on improving the ability of trunk muscles to stabilize the spine, beginning with training to isolate the deeper abdominal muscles as well as deep dorsal trunk muscles. Then patients were progressed to exercises that added leverage of the limbs while maintaining the co-contraction of the deeper abdominal muscles and deep dorsal trunk muscles while breathing normally. Various positions (e.g., supine and quadruped positions) were used to challenge the patients based on their tolerance. Finally, patients were progressed to exercises in more functional positions that included tasks/activities that were reported as challenging and/or painful; patients performed the tasks at the speed demanded by the particular task. Maintenance of the co-contraction of deep trunk muscles was emphasized during these functional activities.

This protocol contained trunk strengthening and endurance exercises. It consisted of 3 phases: 1) initial strengthening of trunk flexors/extensors in single plane movements, 2) trunk and lower-extremity stretching as well as progression of trunk-strengthening exercises to include multi-planar trunk movements. Aerobic exercises were progressed as tolerated and patient education about body biomechanics were reinforced, and 3) trunk-strengthening exercises under dynamic conditions (e.g., unstable support surface and in multi-planar trunk movements). During the 10 week protocol, exercises became more challenging, and each subject had to complete at least the first phase before moving onto the next phase in order to be included in post-testing analyses. There was no specific focus on the deep abdominal or deep dorsal trunk muscles during any of these exercises.

Disability; Scale 0-100% Lower score is considered better/improved Negative value indicates improvement

Disability; Sacle 0-100% Lower score is considered better/improved; Negative value indicates improvement

Disability; Sacle 0-100% Lower score is considered better/improved; Negative value indicates improvement

Inclusion Criteria: a history of chronic LBP with or without recurrences for a minimum of 12 months between 21 - 55 years of age able to stand and walk without assistance have an Oswestry Disability Score of 19% or higher Exclusion Criteria: any major structural spinal deformity including scoliosis, kyphosis, or stenosis spinal fracture or dislocation osteoporosis ankylosing spondylitis rheumatoid arthritis disc herniation with corroborating clinical signs and symptoms serious spinal complications such as tumor or infection previous spinal surgery frank neurological loss, i.e., weakness and sensory loss pain or paresthesia below the knee etiology of LBP other than the lumbar spine, e.g., hip joint history of neurological disease which required hospitalization active treatment for cancer history of unresolved cancer pregnancy or less than 6 months post-partum or less than 6 months post weaning magnified symptom-behavior worker's compensation or disability case in litigation for the LBP problem have a BMI ≥ 30

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