The purpose of this experiment is to determine the effects of a non-thrust manipulation procedure on muscle function, spinal mobility, and pain level on those experiencing low back pain (LBP) in a sample of individuals who identify English as their primary language. The rationale for this language criterion is provided in Section 9:F of this application. Muscle function will be measured via the muscle thickness of a deep spinal stabilizing muscle (multifidus, MF) while in both a resting state and during a maximum voluntary contraction (MVC). Spinal mobility will be measured as the active range of motion of both forward and backward trunk bending. Pain level will be a self-report measure recorded during rest and active range of motion.

Hypothesis 1: A non-thrust manipulation procedure will increase the thickness of the sacral multifidus both at rest and during a maximum voluntary contraction

Hypothesis 2: A non-thrust manipulation procedure will result in greater low back active range of motion.

Hypothesis 3: A non-thrust manipulation procedure will result in a reduction in the participant's self-reported pain levels both at rest and during active range of motion movements.

The proposed study aims to determine if the impact of a newly-described manual procedure, that includes a non-thrust force applied to the low back region, has an impact on patient centered-outcomes. Rehabilitation Ultrasound Imaging (RUSI) will be used to determine MF muscle thickness (MT) at rest and during a maximum voluntary contraction (MVC) immediately following application of the manual procedure.

Inclusion Criteria:

1. Participants are individuals with current complaint of low back pain, defined as pain that is present in the region from just below the rib cage to just below the buttocks.
2. Participants will be 18 years of age or older
3. Participants must be experiencing an episode of low back pain at the present time that is at any level on a Numerical Pain Rating Scale & Pain Diagram (NPRS) from 1-10
4. Participants must demonstrate the ability to maintain standing and prone postures for several minutes at a time and perform lumbar active range of motion in a standing position
5. Participants must report the presence of their low back pain during performance of active forward and/or backward bending in standing
6. Participants must demonstrate the ability to communicate in conversational English, that includes speaking, reading, and writing.

Exclusion Criteria:

1. Participants who are currently involved in litigation that is directly related to the participant's current episode of low back pain

2. Participants with known or suspected pregnancy

3. Participants with confirmed diagnosis of any of the following conditions:

   • Central nervous system disorder
   • Rheumatoid Arthritis
   • Spinal Fracture
   • Spondyloarthropathy (i.e., Ankylosing Spondylitis)
   • Tumor or infection of the spine