The Effect of Thoracic Spine Mobilization On Lower Trapezius Strength Testing

Abstract

Evidence has shown that muscle strength and function become altered due to motion restrictions. Strengthening muscles with traditional therapeutic exercise will not be completely successful unless inhibition is removed by restoring normal joint mechanics. This study investigated the effect of Grade-IV thoracic spine mobilizations on lower trapezius strength testing in normal subjects. The mobilization for the treatment group (n=20) consisted of posterior-anterior (P-A) oscillations performed from T6-T12 at each segment's end range (Grade-IV). This technique is aimed at restoring normal joint play. The control group (n=20) received a Grade-I mobilization consisting of P-A oscillations performed at the beginning of the joint's range, which is not expected to have articular reflexogenic effects. Before and after the mobilizations, isometric muscle strength of the lower trapezius was measured using a Nicholas Manual Muscle Tester. An independent group t-test comparing the groups demonstrated a statistically significant effect of thoracic spine mobilization on lower trapezius strength testing (P<.05).