Table 1 Eligibility criteria

 Age 18–40 years

Age range of most active-duty military personnel

 Able to provide voluntary written informed consent

Able to comprehend trial details and make independent decisions without impairment

 Active-duty status at Naval Air Station Pensacola

Chiropractic care and assessment instruments available only to active-duty personnel at Naval Air Station Pensacola

 Self-reported acute, subacute, or chronic low back pain severity at initial screen and baseline visit 1 with a pain intensity of ≥2 within the past 24 h on a 0–10 numerical rating scale

Low back pain with enough severity likely to demonstrate reduced strength, balance, or endurance

 Any chiropractic care within 30 days prior to informed consent

Prevent possibility of carryover effects from recent care

 Low back pain confirmed or suspected to arise from a visceral source

Evaluation or care outside trial scope required

 Spinal pathology or other condition contraindicating spinal manipulation

Evaluation or care outside trial scope required

 Spinal fracture within the past 6 months

To ensure safety in strength, balance, and endurance tests

 Spinal surgery within the past 6 months

To ensure safety in strength, balance, and endurance tests

 Low back pain with presumptive or confirmed spinal nerve root compression

To ensure safety in strength, balance, and endurance tests

 Imaging evidence of neuroforaminal or spinal canal stenosis or the clinical presentation of neurogenic claudication

To ensure safety in strength, balance, and endurance tests

 Chronic pain syndrome diagnosis

Condition not under study and evaluation or care outside trial scope required

 Diagnosis or suspicion of inflammatory spinal arthropathy

Condition not under study and evaluation or care outside trial scope required

 Referral needed to evaluate or treat an urgent or emergent condition or to determine status of a condition pertaining to eligibility

Evaluation or care outside study scope

 Unable to perform strength, balance, or endurance tests safely, or unable to assess health status

To ensure safety in strength, balance, and endurance tests

 Pregnancy or planning to become pregnant within the next 6 weeks

To ensure safety in strength, balance, and endurance tests and to avoid confounding assessments due to changing physical status during pregnancy

 Knowledge of impending transfer or absence during trial period

To ensure ability to comply with trial protocol

 Seeking or referred to medical evaluation board or physical evaluation board regarding disability status

To ensure safety in strength, balance, and endurance tests and to ensure ability to comply with trial protocol

 Unable or unwilling to comply with trial protocols

To ensure able to comply with trial protocol

 Patellar height is <15 in. (38.1 cm) or >25.5 in. (64.8 cm)

To ensure strength assessment can be performed within protocol