Healthy Volunteer Inclusion Criteria:

- Absence of a history of chronic pain in the targeted anatomical location (i.e., lower back and low extremities) that had limited activities of daily living or work.

- A numerical current pain index of less than 0.5 (on a 10-point Visual Analog Scale).

- Able to understand the goal of the project and give informed consent..

Healthy Volunteer Exclusion Criteria:

- Pregnancy or breastfeeding.

- Any contraindication to an MRI exam.

- Previous severe/acute back or low extremity injury (including fracture).

- Previous back or low extremity surgery.

- Back and lower limb deformities.

- Inability to provide consent.

Myofascial-Related Pain Patient Inclusion Criteria:

- A history of chronic low back or leg pain (the targeted location will be determined based on the findings in Aim 1) for at least 3 months. (Measured by patient history and physical exam).

- A palpable taut band or nodule within the skeletal muscle.

- Hypersensitive tender spot within the taut band.

- Recognition of current pain complaint by pressure on the tender nodule/taut band.

- Painful limit to the full stretch range of motion.

Myofascial-Related Pain Patient Exclusion Criteria:

- Pregnancy or breastfeeding.

- Any contraindication to an MRI exam.

- Previous therapy in the area to be treated within 6 months.

- Previous severe back or low extremity injury (including fracture) or surgery.

- Any neurological conditions or active systemic disease (e.g., diabetes, peripheral vascular disease, cancer, rheumatoid arthritis) that impaired sensation/pain perception.

- Severe osteoarthritis.

- Skin injuries in the area to be treated.

- Inability to provide consent.