TRUNK ISOKINETIC STRENGTH AND ENDURANCE IN TWO GROUPS OF PEOPLE WITH CHRONIC LOW BACK PAIN: A LONGITUDINAL RETROSPECTIVE STUDY
Résumé
Background: Multidisciplinary functional restoration programs target physical, psychological and social aspects of chronic low back pain (CLBP). Objective: To assess changes in isokinetic trunk muscle strength and endurance after an intensive (IFRP) or a semi-intensive (SIFRP) (32 hours of physical activity) functional restoration program in participants with CLBP. Methods: Design: longitudinal, single-center, retrospective study. Setting: Physical and rehabilitation medicine department, of a tertiary care center. Trunk flexor and extensor muscle strength (60°.s-1) and endurance (120°.s-1) were measured with the Humac NORM isokinetic dynamometer. Change in isokinetic variables (peak torque, total work and flexor/extensor ratio) after each program was assessed with a paired t-test (p<0.05). Pearson’s rho and multiple linear regression assessed associations between changes in isokinetic and clinical variables and demographic characteristics. Results: We included 64 individuals (52.5% female, 41.7 [9] years) in the IFRP and 64 (74% female, 45.3 [11.2] years old) in the SIFRP group. Trunk extensor peak torque (+11 and +13.8%) and extensor (+26.3 and +13.2%) and flexor (+14.7 and +7.1%) total work improved in the IFRP and SIFRP groups respectively, p<0.001. No correlations were significant and no variables significantly predicted improvement in extensor total work in either group. Conclusion: Significant short-term improvements occurred in trunk extensor strength and flexor and extensor endurance after both the intensive and semi-intensive functional restoration programs. Changes in isokinetic variables were independent of changes in clinical variables. Assessing isokinetic variables could help to phenotype individuals with CLBP and specify the content of the functional restoration programs at the best cost.