Chiropractic and pain sensitivity in people with lower back pain

The initial visit will involve randomisation to receive either an active intervention or sham. The active intervention is a single high-velocity low-amplitude lumbar manipulation targeting the L5-S1 facet joint on the participant's most symptomatic side. The participant will be in the side-lying position, with the upper leg bent and lower leg straight. The clinician will contact the target joint with their hand, and stabilise the participant at the shoulder and knee. The clinician will then deliver a rapid and short thrust into the joint into the joint. A “cracking” or “popping” noise may be heard during the SMT. This will take approximately 1 minute to complete, and will be delivered in a private research room, on a chiropractic examination table, by a chiropractor with a minimum of 3 years clinical experience. Several chiropractors will deliver these interventions, and will receive training to standardise techniques and participant interaction, in the form of a single 30-60 minute small group workshop run by a researcher who is also a chiropractor. At each of 3 follow-up visits, the intervention is a pragmatic chiropractic treatment (not randomised) involving a combination of mid and lower back spinal manipulation, spinal mobilisation, soft tissue therapy, education, and advice as appropriate for the individual participant. The specific treatment approach will be determined based on the participant's history and physical examination. The follow-up treatments are expected to take 10-15 minutes, and are intended to replicate an evidence-based private practice chiropractic treatment. These will be delivered by a researcher who is a chiropractor with >3 years clinical experience, and each of the 3 follow-up visits will occur within 4-10 days of the previous visit. Treatment notes will be kept at each follow-up visit, recording symptomatic change, physical examination findings, specific treatments delivered, and advice provided.