Mechanisms of Specific Trunk Exercises in Low Back Pain

The research objective is to determine which physical therapy (PT) treatment is the most efficacious for patients with lower back pain (LBP), who have been subgrouped based on certain clinical features. There is only limited evidence that supports any one PT treatment for patients with LBP since PT treatment outcomes for exercise protocols are equivocal, given the heterogeneous clinical features of patients with LBP. Thus, classification of patients with LBP into subgroups with shared clinical features has been identified as a research priority by several groups in order to prescribe the most efficacious PT treatment for each homogeneous subgroup. The investigators hypothesize that particular PT treatments are most efficacious when applied to patients with LBP, who present with particular clinical and neuromuscular features.

The proposed studies focus on 2 schemas to classify LBP: 1) the Treatment-Based Classification (TBC) system, from which clinical prediction rules about who is most likely to benefit from spinal stabilization exercises (among others) have been developed, and 2) the Movement System Impairment-Based Classification (MSI) system, which includes 5 classifications of LBP named for the specific direction(s) of movements and alignments associated with the person's LBP. The primary purpose of this proposal is to conduct a prospective, randomized, controlled Phase II clinical trial in order to examine whether or not treatment matched to a patient's specific signs and symptoms (patient-matched) per the TBC is more effective than the MSI system for improving short- (6 weeks) and long-term (12 and 24 months) outcomes in people with chronic LBP. A secondary purpose is to identify prognostic factors that predict clinical outcomes in the 2 treatment groups being compared. Subjects will be assigned to one of two study arms: eligible for Treatment-Based Classification (TBC) stabilization exercises based on current criteria ('Eligible' Subject Group); and subjects who are not eligible for the TBC-based stabilization exercises ('Ineligible' Subject Group). Within in each study arm, subjects will be randomly assigned to 1 of 2 exercise protocols for a 6-week period: stabilization - a protocol focused on improving the motor control of trunk muscles to stabilize the spine; or MSI-based - a classification-specific treatment focused on education and instruction for modifying movement strategies during functional activities, and on exercises specific to the classification category. Laboratory measures (muscle activation, kinematics, forces) during standardized tasks will quantify neuromuscular impairments associated with LBP and clinical questionnaires will quantify changes in pain, function, and health status pre- and post-treatment. The addition of neuromuscular measures to these classification schemas could improve the sensitivity and specificity of each.

Subjects between the ages of 21-55 years with low back pain >12 months who are eligible for Treatment-Based Classification (TBC) stabilization exercises based on current criteria: straight leg raise > 90 degrees aberrant trunk movement with trunk forward flexion positive prone instability test AND/OR passive lumbar mobility testing that is judged to be hypermobile at any level.

Subjects between the ages of 21-55 years with low back pain >12 months who are not eligible for the TBC-based stabilization exercises based on current criteria

Subjects between the ages of 21-55 years with low back pain >12 months who are eligible for Treatment-Based Classification (TBC) stabilization exercises based on current criteria: straight leg raise > 90 degrees aberrant trunk movement with trunk forward flexion positive prone instability test AND/OR passive lumbar mobility testing that is judged to be hypermobile at any level.

Subjects between the ages of 21-55 years with low back pain >12 months who are not eligible for the TBC-based stabilization exercises based on current criteria

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 and then incorporation of these isolated contractions into other exercises. The exercise protocol progresses to include trunk flexion and extension strengthening exercises as well as abdominal bracing exercises in supine and quadruped positions, and finally to exercises in more functional positions.

The MSI-classification based approach focuses on education and instruction for modifying movement strategies during functional activities, and on exercises that are specific to the classification category. First there is an analysis of and instruction in modifying a subject's direction-specific alignment and movement strategies during symptomatic functional activities. Second, there is education about the principles of tissue injury and healing, and how cumulative tissue stress contributes to microtrauma and LBP. Unique to the education process is the emphasis on how using one's particular movement strategies during functional activities may accelerate tissue stress accumulation because the strategies are used repetitively. Thirdly, there is exercise prescription that includes practice in performing modified versions of the direction-specific impairment tests from the physical exam, with an emphasis on impairments that can be modified to eliminate LBP symptoms.

fear-avoidance beliefs about physical activity Scale for Physical Activity 0-24; sum items 2, 3, 4, 5. Higher score indicates higher fear beliefs about physical acitivty

fear-avoidance beliefs about physical activity Scale for Physical Activity 0-24; sum items 2, 3, 4, 5. Higher score indicates higher fear beliefs about physical acitivty

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 AND/OR less than an 8 on one activity reported on the Patient Specific Functional Scale, 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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