Chiropractic adjustment and brain, eyes and heart activity

Chiropractic Intervention: The entire spine and both sacroiliac joints will be assessed for vertebral subluxations and adjusted where deemed necessary by an experienced chiropractor of minimum 10 years’ experience. The clinical indicators of vertebral subluxations include tenderness to palpation of the relevant joints, manual palpation for restricted intersegmental range of motion, palpable asymmetric intervertebral muscle tension, and any abnormal or blocked joint play and end-feel of the joints. These clinical indicators are routinely used by chiropractors when analysing the spine and have previously been shown to be reliable for the identification of vertebral subluxations when used as a multidimensional battery of tests. Any chiropractic spinal adjustments will involve a high-velocity low-amplitude thrust, a standard chiropractic technique, to sites deemed to have vertebral subluxations as identified using the indicators above. These adjusting techniques have been previously used in studies that have investigated neurophysiological effects of spinal adjustments [for review see Haavik et al., 2021]. The chiropractic intervention will be delivered in a single session and will take around 10 minutes. Before and after the chiropractic or control intervention, participants will perform alternating trials of immersing their hands in cold water and performing a mental arithmetic task (Maastricht Acute Stress Test).