Excellent study on impingement & Serratus Anterior (SA) function!
Reference:Ludewig P, Cook T. Alterations in Shoulder Kinematics and Associated Muscle Activity in People With symptoms of Shoulder Impingement. Physical Therapy. 2000;3: 277-291
52 subjects (� asymptomatic and � with impingement syndromes) were recruited from a population of construction workers with routine exposure to overhead work
EMG data were collected from the upper fibers of trapezius (UFT), lower fibers of trapezius (LFT) and the SA during shoulder elevation
Electromagnetic sensors simultaneously tracked the 3D motion of the scapula and the humerus during shoulder elevation
Result:Relative to the asymptomatic group, the impingement group showed:
1. Decreased upward rotation during the initial phase of shoulder elevation
2. Increased anterior tipping at the final phase of shoulder elevation
3. Increased scapular winging when a load was added during shoulder elevation
4. Increased UFT and LFT EMG activity during the mid and final phases of shoulder elevation
5. Decreased SA activity throughout shoulder elevation with and without added load
Clinical Relevance: Scapular anterior tipping, winging and loss of upward rotation are essential to consider in the rehabilitation of patients with symptoms of shoulder impingement related to occupational exposure to overhead work, as they all indicate a functional loss of the SA muscle.
Personal Comment:While doing pushups or bench presses, some individuals allow their scapulae to “fall back” into retraction throughout the exercise. In this case they strengthen their pectorals and triceps but at the expense of the SA muscle. Advice on maintaining some protraction during most of the range is essential here!
Posted on: February 12, 2002