What this trial measures

• Lumbar Spine Magnetic Resonance Imaging (MRI)Baseline, Pre-Intervention; Immediately after intervention

  Diagnostic imaging of the lumbar spine including T1, T2, and Dixon Fat-Water images. Measures of intervertebral disc height and hydration will be extracted from each lumbar level (L1-L5). Intervertebral disc height will be measured on both T1- and T2-weighted images. The T2-weighted image will assess water signal intensity for intervertebral disc hydration. Muscle quality from the axial Dixon fat-water images will be assessed using the percentage of signal from fat (muscle fat infiltration), a measure of muscle quality. Muscle quality will be assessed in the left and right multifidi, erector spinae, quadratus lumborum, and psoas major muscles.

• 3D Motion CaptureBaseline, Pre-Intervention; Immediately after intervention

  A markerless motion capture system will measure kinetics and kinematics of functional tasks. Variables of interest include joint angles, limb symmetry, ground reaction forces, double- and single-leg stance percentages, and anticipatory postural acceleration. Tasks include 1) isometric chest raise, 2) tandem balance, 3) sit-to-stand, 4) timed up and go (with gait), and 5) step-up / step-down.

• Surface ElectromyographyBaseline, Pre-Intervention; Immediately after intervention

  Lumbar neuromotor activation will be assessed with EMG collection (2 kHz) on bilateral musculature, specifically the erector spinae, quadratus lumborum, and gluteus maximus muscles.

• MyotonometerBaseline, Pre-Intervention; Immediately after intervention

  A measure of passive stiffness of the low back muscles (erector spinae, quadratus lumborum, gluteus maximus) at rest (prone) with a MyotonPRO. The MyotonPRO utilizes oscillation accelerometry to measure five output variables of soft tissue: tone (Hz), stiffness (m/sec), elasticity, relaxation (msec), and creep.

• Sensorimotor Reflex (H-Reflex)Baseline, Pre-Intervention; Immediately after intervention

  This electrically evoked response is analogous to a monosynaptic stretch reflex. It is used to assess functionality of the peripheral nervous system (diagnosing and monitoring peripheral neuropathies, radiculopathies, and motor neuron diseases; investigation of mechanisms of motor control, plasticity, and adaptation in response to interventions). The H-reflex is particularly valuable in evaluating the excitability of the alpha motor neurons and their synaptic inputs, which can be affected by IVD lesions. A low-intensity electrical stimulus is applied to a mixed peripheral nerve (commonly the tibial nerve) to preferentially activate the Ia afferent fibers. A Digitimer DS7R will provide an electrical stimulus to a sensory neuron. A recording electrode measures the resultant reflexive muscle response which is recorded with surface EMG from the corresponding muscle, providing timing to the sensorimotor reflex loop.