Linking Physiological Responses to Clinical Outcomes Following Cervical Spine Manipulation

Inclusion criteria: All participants: * 18-65 years of age * English and/or French and/or German proficiency (to guarantee proper understanding of instructions and informed consent) * Provision of informed consent People with neck pain: * Mechanical neck pain located inferior to the superior nuchal line and inferior border of the mandible and superior to the superior border of the clavicle, suprasternal notch and scapular spines bilaterally * Neck pain of ≥ 12 weeks duration * Neck pain not associated with an identified pathological cause * Who have not received treatment for their neck pain (e.g. spinal manipulation, spinal mobilization, massage etc) in the previous 2 weeks Exclusion criteria: All participants: * Unable to provide informed consent (e.g. due to language difficulties) * Any neurological condition * Any major medical or psychiatric condition (e.g. cardiovascular disease, diabetes, autoimmune disorders, major depressive disorder) * Conditions and/or medications that could affect heart rate variability signals (e.g. hypertension, obesity (body mass index \> 30), the current use of pain medications, steroids, antidepressants and/or β-blockers) * Any chronic pain condition other than neck pain (e.g. low back pain) * Pregnancy (all females will be asked verbally if there is a chance they are pregnant during screening) People without neck pain: * Acute pain * Neck pain (\> 3 consecutive days) in the last year People with neck pain: * Neck pain that does not originate from the cervical spine * Who have received treatment for their neck pain (e.g. spinal manipulation, spinal mobilization, massage etc) in the previous 2 weeks * Who have taken medication within the past 24 hours prior to the first visit and during their participation in the study * All contraindications to the application of spinal manipulation and mobilization (e.g. personal or family history of a connective tissue disorder, current use of anticoagulant therapy, history of recent surgery and/or neck trauma, facial or intra-oral anesthesia or paresthesia, visual disturbances, dizziness and/or vertigo). Such contraindications will be screened during the medical history and physical examination performed by a registered health care clinician (e.g. chiropractor). Any participant not meeting the inclusion and exclusion criteria will be excluded from the study. As in routine daily clinical practice at the Balgrist University Hospital Chiropractic Polyclinic, the ultimate decision whether it is appropriate to deliver an intervention to the participant (spinal manipulation and/or mobilization) will be determined by the clinician delivering the treatment. The investigator is responsible for coordinating adequate medical care if complications occur. Possible subsequent medical care is contingent on the nature of the complication and could range from referral to the on-site Chiropractic Department Polyclinic for follow-up treatment of muscle soreness to referral to the Emergency Department of the Balgrist University Hospital (not expected).