Biopsychosocial Factors and Muscle Morphology After a Resistance Exercise

Assessing Adaptations in Biopsychosocial Factors and Muscle Morphology After a Resistance Exercise Intervention in Individuals With Low Back Pain

The purpose of this study is to evaluate the longitudinal effects of a four-week dynamic resistance training program using the 45-degree Roman chair on pain sensitivity changes after exercise and lumbar muscle performance in individuals with chronic low back pain (LBP). This study will consist of three specific aims. Aim 1 examines changes in local exercise-induced hypoalgesia. Aim 2 will assess changes in lumbar multifidus and erector spinae thickness using ultrasound imaging before and after the intervention. Aim 3 will evaluate changes in lumbar extensor strength (handheld dynamometry (HHD)) and endurance (Biering-Sørensen test).

Inclusion Criteria:

• chronic low back pain lasting ≥ 12 weeks
• current pain intensity ≥ 3/10 but no higher than an 8/10 on the Numeric Pain Rating Scale (NPRS) within the past 48 hours
• resistance trained (defined as 2x/week for the past 8-12 weeks)
• able to read and speak English for informed consent and completion of questionnaires
• willing and physically able to complete all testing and intervention sessions.

Exclusion Criteria:

• History of spinal surgery, fusion, or fracture within the past 6 months
• diagnosed degenerative disc disease, scoliosis, or spinal pathology that precludes safe exercise participation
• use of an assistive device for walking (cane, walker) within the past year
• pregnancy, due to contraindications for exercise testing and ultrasound -body weight ≥ 300 lbs., which exceeds the safe capacity of the Roman chair --
• current tobacco/nicotine use
• current enrollment in physical therapy or structured rehabilitation for LBP,
• cardiovascular, pulmonary, metabolic, or systemic disease that increases risk during exercise
• nociplastic pain conditions (e.g., fibromyalgia) or neurological conditions that confound EIH responses
• inability to complete ≥ 8 Roman chair repetitions with proper form during screening
• non-English speaking