Background. PA movements are frequently used to assess and treat patients with neck pain, but little is known about their relationship to patient symptoms or the mechanism of their effect. Objectives. To determine the relationship between changes in stiffness of unilateral posterior-anterior (PA) movements, active range of movement (AROM) and indicators of sympathetic nervous system (SNS) function in patients with non-acute neck pain were measured immediately before and after manual therapy treatment. Methods. One symptomatic and one asymptomatic location were selected in 20 patients with non-acute neck pain. AROM, PA stiffness at each location and indicators of SNS function were measured before and after each of three manual therapy interventions and a control intervention. Results. Following treatment to the symptomatic location, there was a significant correlation between decreased mean PA stiffness at that location and increased total AROM (R = -0.596). The only individual axes of AROM that demonstrated a significant correlation was lateral flexion (R = -0.459). All regions of PA stiffness above 8 N demonstrated significant correlations with total AROM (R = -0.466 to -0.628). Although some changes in SNS measures were found following treatment, no correlations were found with changes in AROM. Conclusions. Increased posterior-anterior stiffness at locations deemed to be symptomatic is related to reduced AROM of the cervical spine in patients with non-acute neck pain. The therapeutic effects of treatment on PA stiffness are localized to the treated location and no indication was found of the effect being mediated through the SNS.