Assessment of chiropractic care on strength, balance, and endurance in active-duty U.S. military personnel with low back pain: a protocol for a randomized controlled trial

BACKGROUND: Low back pain (LBP) is a common cause of disability among U.S. military personnel. Approximately 20% of all diagnoses resulting in disability discharges are linked to back-related conditions. Because LBP can negatively influence trunk muscle strength, balance, and endurance, the military readiness of active-duty military personnel with LBP is potentially compromised. Chiropractic care may facilitate the strengthening of trunk muscles, the alteration of sensory and motor signaling, and a reduction in pain sensitivity, which may contribute to improving strength, balance, and endurance for individuals with LBP. This trial will assess the effects of chiropractic care on strength, balance, and endurance for active-duty military personnel with LBP. METHODS/DESIGN: This randomized controlled trial will allocate 110 active-duty military service members aged 18–40 with non-surgical acute, subacute, or chronic LBP with pain severity of ≥2/10 within the past 24 h. All study procedures are conducted at a single military treatment facility within the continental United States. Participants are recruited through recruitment materials approved by the institutional review board, such as posters and flyers, as well as through provider referrals. Group assignment occurs through computer-generated random allocation to either the study intervention (chiropractic care) or the control group (waiting list) for a 4-week period. Chiropractic care consists primarily of spinal manipulation at a frequency and duration determined by a chiropractic practitioner. Strength, balance, and endurance outcomes are obtained at baseline and after 4 weeks. The primary outcome is a change between baseline and 4 weeks of peak isometric strength, which is measured by pulling on a bimanual handle in a semi-squat position. Secondary outcomes include balance time during a single-leg standing test and trunk muscle endurance with the Biering-Sorensen test. Patient-reported outcomes include pain severity, disability measured with the Roland Morris Disability Questionnaire, symptom bothersomeness, PROMIS-29, Fear Avoidance Beliefs Questionnaire, expectations of care, physical activity, and global improvement. DISCUSSION: This trial may help inform further research on biological mechanisms related to manual therapies employed by chiropractic practitioners. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02670148 Registered on 1 February 2016. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13063-018-3041-5) contains supplementary material, which is available to authorized users.