Abstract
Lower trapezius muscle-strength deficits are a common clinical finding in patients presenting with poor postural habits. It has been speculated that zygapophyseal extension restrictions in the middle to lower thoracic spine are associated with these muscle-strength deficits. This may be a direct result of muscle inhibition related to reflexogenic influences from dysfunctional joints. The purpose of this study was to investigate the effects of manipulation applied to the lower thoracic spine (T6-T12) of asymptomatic individuals on lower trapezius muscle strength. A convenience sample of 40 subjects was randomly split into control and experimental groups of equal size. Pre-test and post-test measurements of isometric lower trapezius muscle strength were collected using a Nicholas Manual Muscle Tester. Both groups received identical assessment procedures. The experimental group received thoracic manipulations while the control group received a placebo technique. An independent group t-test was used to compare the mean change in lower trapezius muscle strength between the groups. Results revealed a significantly greater (p < 0.025) percentage increase in lower trapezius strength in the manipulation group (14%) as compared to the controls (3%). The results suggest that lower thoracic manipulation techniques may be beneficial in reducing the lower trapezius muscle inhibition commonly associated with many postural syndromes.
Keywords: Keywords THORACIC MANIPULATION; SPINAL MANIPULATION; LOWER TRAPEZIUS MUSCLE STRENGTH; UPPER CROSSED POSTURAL SYNDROME