SPECIFIC TRUNK EXERCISES DO NOT PREFERENTIALLY IMPROVE PAIN, MUSCULOSKELETAL IMPAIRMENTS, OR FUNCTION IN SUBJECTS WITH MECHANICAL LOW BACK PAIN: A PILOT STUDY. Andrea L. Trombley*1; Stephanie L. Jones2; Sharon M. Henry2; Janice Y. Bunn3 1. Work Enhancement Rehabilitation Center, Fletcher Allen Health Care, Burlington, VT; 2. Physical Therapy, University of Vermont, Burlington, VT; 3. Mathematics & Statistics, University of Vermont, Burlington, VT PURPOSE: The purpose of this investigation was to compare the effect of two exercise protocols (specific exercise vs. strengthening/conditioning) on pain [Numeric Pain Index (NPI)], musculoskeletal impairments such as muscle length and strength of the lumbar spine and hip, disability [Modified Oswestry Low Back Pain Disability Questionnaire (OSW)] and function [Patient-specific Functional Scale (PSFS)]. BACKGROUNDS/SIGNIFICANCE: Specific trunk stabilization programs are gaining popularity for the treatment of persons with chronic low back pain (LBP) but require much treatment time for the patient to master. Thus it is important that such programs are evaluated for superior outcomes in terms of pain, impairments, and function to justify their inclusion into regular treatment regimes for various subgroups of LBP patients. SUBJECTS: Participants were referred to PT clinics and met the inclusion criteria for chronic (>6 months), recurrent mechanical LBP. Fifteen patients were assigned to one of two exercise protocols: 1) specific exercise (SEG; n = 6); and 2) strengthening/conditioning (SCG; n = 9). Subjects were treated once per week for 10 weeks. The two groups did not differ significantly in pain scores, hip abductor and hip flexor length or trunk strength at the initiation of treatment. Common to both groups were large proportions of participants (SCG = 77.8%; SEG = 100%) classified as weak on a leg lowering task. A subgroup of patients (n= 12; SEG = 6, SCG = 6) did not differ on disability or function scales prior to treatment. METHODS AND MATERIALS: Data on pain and musculoskeletal impairments were collected prior to and following 10 weeks of treatment for all patients, and data on disability and function were collected at weeks 1, 5, and 10 for a subgroup of patients (n = 12). Musculoskeletal impairment measures included muscle length and strength testing of the lumbar spine and hip per the NIOSH Low Back Pain Atlas1. The SEG protocol consisted of isometric contractions of the transversus abdominis (TrA) and multifidus (MUL) muscles in various positions. Once co-contraction of the two muscles was mastered, varying amounts of limb load were added to further challenge the maintenance of the co-contraction. Lastly, subject-specific positions/activities known to increase symptoms were used while the subject practiced co- contracting the TrA and MUL muscles. The SCG protocol consisted of gentle stretching of trunk/lower limbs initially followed by progressive trunk/limb strengthening/stretching exercises once pain was reduced and/or controllable. Common to both protocols were aerobic conditioning and instruction in pain management and body mechanics. ANALYSES: Results are from analysis of co-variance of pre/post change scores, with the baseline effect included as the covariate to identify differences between protocols (SEG, SCG), and from repeated measures analysis of variance to identify changes across time. RESULTS: Participants in both the SEG and the SCG protocol reported a decrease in pain (NPI) following 10 weeks of treatment (p<0.01) that did not differ between the two groups. However, participants in the SEG protocol demonstrated no change in musculoskeletal impairment measures following treatment. In contrast, participants in the SCG demonstrated significant improvements in lumbar flexion and extension (p = 0.01; p = 0.03, respectively) compared to the SEG protocol. In addition, a greater proportion of participants in the SCG were classified as strong on a leg-lowering task as a measure of abdominal strength after treatment (SCG = 88.9% vs. SEG = 40%;) although the finding is not statistically significant (p = 0.09). The subgroup of subjects in the SCG (n = 6), compared to the SEG protocol (n = 6), demonstrated a greater decrease in disability (OSW) at Week 10 compared to Week 1 (p=0.002). The function (PSFS) for subjects in the SCG protocol improved over time (p=0.004) but not for those in the SEG protocol (p=0.067). CONCLUSIONS: Although participants in both treatment protocols demonstrated a decrease in pain after 10 weeks of rehabilitation, only persons in the SCG exhibited superior increase in range of motion measures of the trunk, decrease in disability, and increase in function. The SEG protocol has been shown preliminarily to be effective in reducing pain and disability, and increasing function in a subgroup of persons with spondylolysis/sponylolisthesis2. However, the specific focus on TrA and MUL muscle control may not be warranted for the LBP subgroup in this study, given the results of this pilot study and the amount of treatment time needed for the patient to master the SEG protocol. 1 Nelson RM and Nestor DE. Atlas of standardized low-back test and measures of the National Institute for Occupational Safety and Health. Scandanavian Journal of Work, Environment and Health. 14 Suppl 1:82-4, 1988 2O'Sullivan P, Twomey L, Allison G. Evaluation of specific stabilization exercise in the treatment of chronic low back pain with radiologic diagnosis of spondylolysis or spondylolisthesis. Spine. 1997;22:2959-2967 FUNDING SOURCE: Office of Patient-Oriented Research, Fletcher Allen Health Care, Burlington, VT and NIH/NCMRR/R01 HD04099 KEYWORDS: Low Back Pain, Specific Trunk Stabilization Exercise Copyright 2009 by the American Physical Therapy Association. Requests for reprints should be directed to the corresponding author of the article. Educators, students, and other academic customers may receive permission to reprint copyrighted material from Physical Therapy (ISSN 1538-6724) by contacting the Copyright Clearance Center Inc, 222 Rosewood Dr, Danvers, MA 01923. Other types of customers who want permission to reprint should contact the APTA Editorial Office, Attn: Physical Therapy.