The effect of manipulation and mobilisation on pressure pain thresholds in the thoracic spine

BACKGROUND AND OBJECTIVES: High velocity low amplitude thrust manipulation and mobilisation are commonly used by manual therapists to relieve spinal pain and improve mobility. The aim of this controlled, single blinded study was to investigate the effect of manipulation and mobilisation on pressure-pain thresholds in the thoracic spine in an asymptomatic population. METHODS: Subjects (n=96) were screened for tender thoracic segments, and pressure-pain threshold measurements were made using an electronic pressure algometer immediately before and after treatment intervention. Subjects were randomly allocated into three intervention groups, and received either a single high velocity extension thrust, thirty seconds of extension mobilisation, or thirty seconds of sham treatment (control) consisting of simulated ‘laser acupuncture’. ANALYSIS: Within-group pre- and post-intervention pressure-pain threshold values were analysed using dependent t-tests, revealing significant changes in the mobilisation (P<0.01) and manipulation (P=0.04) groups, but not the sham treatment group (P=0.88). Analysis of mean group changes using a one-way analysis of variance and post-hoc analysis revealed a significant difference between the mobilisation and control group (P=0.01), but no significant difference between the manipulation and control group (P=0.67). Pre-post effect sizes in the mobilisation group were medium to large (d=0.72), small to medium for manipulation (d=0.32), and small in the control group (d=0.02). CONCLUSION: Both manipulation and mobilisation produced significantly increased pressure-pain thresholds (decreased sensitivity to pressure) in the thoracic spine, whereas the sham treatment did not. Mobilisation appeared to be more effective than manipulation for increasing pressure-pain thresholds when applied to the thoracic spine in asymptomatic subjects.