Isolated Lumbar Extension Resistance Training Is Effective at Improving Extension Power and Disability in Subjects with Diagnosed Lumbar Multifidus Dysfunction

Background: Lumbar multifidus dysfunction is a prevalent cause of disability in individuals with lower back pain. Previous research highlights the benefits of isolated lumbar extension training for non-specific lower back pain, however, studies examining its efficacy in lumbar multifidus dysfunction are lacking. Objective: To evaluate the effectiveness of isolated lumbar extension resistance training on disability and strength in individuals with lumbar multifidus dysfunction. Methods: Subjects underwent a physiotherapy led structured rehabilitation program incorporating isolated lumbar extension. Sessions were conducted twice weekly targeting momentary muscular failure with time under load 90 - 120 seconds and progressions aimed at 5 - 10 lbs increments. Outcomes were assessed using the Oswestry Disability Index and lumbar extension strength testing at baseline and after 12 weeks, with statistical analysis using t-test and chi-squared 2 × 2. Results: Forty-five subjects (24 male, 21 female) with a median age of 48 completed the intervention. Improvements were noted in Oswestry Disability Index scores (median pre: 24, post: 15) and maximal lumbar extension strength (median pre: 122 lb, post: 186 lb), with p ≤ 0.05. Overall, 89% showed improvement in disability scores, 67% moved to a better disability category, and 51% saw at least a 50% increase in strength. No significant gender differences were observed. Conclusions: Isolated lumbar extension resistance training is effective at improving extension power and disability in subjects with lumbar multifidus dysfunction.