Validation of Clinical Tests Used to Identify Patients Who Would Benefit From Trunk Stabilization Exercises: Preliminary Steps to Refine Test Interpretation and Improve Intervention Prescription

Low back pain (LBP) presents a challenge in rehabilitation due to its heterogeneous presentation across patients. However, trunk stabilization exercises have been identified to be successful in patients that meet specific clinical prediction rules. Identifying mechanisms that underlie the tests used in the clinical prediction rules may aid in better understanding impairments in these patients. This may aid in refining intervention selection and prescription. The purpose of this dissertation was to identify mechanisms underlying clinical tests that are used to predict a patient’s success with trunk stabilization exercises: aberrant movements observed during forward bending and the prone instability test. The aims were to: 1) characterize lumbar extensor muscle neuromuscular control during active forward bending and the prone instability test (PIT); 2) validate clinical assumptions of the role that impaired lumbar multifidus muscle activity has in aberrant movements patterns during a forward bend task and a positive prone instability test. Aim 1 results revealed that all trunk extensors are activated to a greater extent in those with aberrant forward bending. However, the lumbar multifidus provided the greatest contribution. In the prone instability test, muscle activity during the leg raising portion of the test resulted in a significant increase in spinal stiffness and reduction in pain. However, participants with LBP had greater reliance on fewer muscle synergies that involved dominance of extrinsic muscles compared to participants without LBP. Aim 2 results revealed that a positive prone instability test with pain reduction and spinal stiffness increase could be yielded in participants with LBP through electrical stimulation of the lumbar multifidus. However, electrical stimulation driven fatigue to the muscle was not able to produce aberrant movement in individuals without LBP. Adaptations in neuromuscular control during forward bending and the prone instability test in individuals with LBP suggest that exercises that include movement control and coordination may be necessary within the intervention.Ph.D., Rehabilitation Sciences -- Drexel University, 201