Participants
pain
People with non-specific neck pain were recruited from General Practitioner clinics and primary care physiotherapy practices in The Netherlands. The first author (ILS) enrolled the participants. People aged between 18 and 65 years, with a minimum pain intensity of 40/100 on a Visual Analogue Scale (VAS), and at least six weeks of non-specific neck pain were eligible to participate in the trialFor longitudinal analyses with three time points (baseline and 2 follow-up times), 80% power to detect a mean (SD) difference of 550 (933) pg/ml for TNF-α, with a two-sided significance level, a correlation of 0.6 among repeated measures and a ratio between the experimental group and control group of 0.33, 91 participants were required. Allowing a ~ 10% drop-out rate, 100 participants were recruited