TY - Generic T1 - The Effect of Low Back Pain on Lumbar Multifidus Muscle Size and Activity Using Rehabilitative Ultrasound Imaging and their Correlation with Functional Outcomes. IFOMPT, World Congress of Manual Musculoskeletal Physiotherapy, Canada, 4th October 2012 Y1 - 2012 A1 - Ryan, A A1 - O’Sullivan, C ER -