Altered scapular kinematics have been documented in many shoulder injuries and pathologies. Assessing faulty movement of the scapulae on the thorax and retraining activation of periscapular and spinal intrinsic musculature should enhance a neuromuscular pattern’s quality to establish a punctum fixum at the thoracic spine and physiological scapula-thoracic articulation (PSTA). Establishing proper fixation of the scapulae on the thorax requires a stiffening of the thoracic spine. Optimal muscle activation pattern from the scapula’s stabilization on the thorax establishes a point of fixation from which the scapula glide, tilt, and rotate about the shoulder girdle axes. This is accomplished by a “stiffening” of the thoracic spine. A specific muscle activation pattern creates an ideal intra-abdominal pressure, stiffening not only the lumbar spine, but also the thoracic spine. This activity establishes a point of fixation and determines the direction of muscle pull of muscles that centrate the PSTA position on the thorax, allowing for an optimal mechanical advantage for upper extremity motion and support functions. This study aims to 1) determine if a balanced abdominal wall activation augments mechanical support of the thoracic spine and 2) determine if a balanced abdominal wall activation affects scapula-thoracic kinematics, specifically scapular upward rotation on the thorax.
