An investigation into the potential hypoalgesic effects of different amplitudes of PA mobilisations on the lumbar spine as measured by pressure pain thresholds (PPT)

Mobilisation of the spine is a common technique used in clinical practice. Studies have shown that mobilisation to the spine can decrease pain. The optimum treatment dose for achieving this has not so far been investigated. Previous studies that demonstrate the pain relieving effects of mobilisations have used large amplitude of oscillations. The importance of amplitude on pain relief has not been established. The current study aims to: a) Investigate the importance of amplitude as part of the treatment dose. b) To explore the extent of any pain reliving effects seen following mobilisations. The study employed a randomised, single blind, within-subjects repeated measure design. Thirty asymptomatic subjects participated. The subjects completed three experimental conditions on three separate occasions. The conditions were: large amplitude of oscillations (forces between 50 and 200 N), small amplitude of oscillations (150 N–200 N) and quasi-static (maintained at 200 N). Each condition involved a 3x1 minute central PA mobilisation at a frequency of 1.5 Hz on the lumbar spine. Pressure pain thresholds (PPT) were measured immediately before and after each intervention at 4 different sites. The sites were chosen to determine the extent of the hypoalgesic response. Results demonstrated a significant increase in PPT following lumbar mobilisations (p = 0.013) at all measured sites. However, no significant difference was found between amplitude conditions (p = 0.864). This study suggests that in asymptomatic subjects a systemic hypoalgesic response is caused by lumbar mobilisation regardless of amplitude