This prospective study compared 3-D shoulder kinematics and scapular muscle EMG in 26 construction workers with impingement symptoms versus 26 matched asymptomatic controls. Subjects performed scapular-plane arm elevation under three load conditions (unloaded, 2.3 kg, 4.6 kg) across the painful arc (31°–120°). The goal was to identify which specific movement and muscle-activation abnormalities actually exist in symptomatic overhead workers.
Before this paper, impingement rehabilitation often meant either generic rotator cuff strengthening or broad scapular stabilization programs — with little objective data to distinguish which muscles were actually dysfunctional.
This study gives you a specific target: serratus anterior, not the trapezius. The trapezius is already overcompensating. Adding more trapezius-dominant exercises (rows, shrugs, Y-T-W variations that load the lower trap) without first restoring serratus anterior function will not correct the anterior tipping deficit at end-range.
When you see an overhead worker with impingement symptoms, the key clinical question is not 'is the scapula moving?' but 'is the anterior acromion being elevated at end-range?' Serratus anterior drives that posterior tipping; the trapezius cannot substitute for it.
One nuance worth knowing: kinematic deficits in this population are load-dependent. A clinical exam with the arm unloaded may look normal. The breakdown appears when the patient holds a tool or weight overhead, exactly replicating their occupational exposure.
This prospective study compared 3-D shoulder kinematics and scapular muscle EMG in 26 construction workers with impingement symptoms versus 26 matched asymptomatic controls. Subjects performed scapular-plane arm elevation under three load conditions (unloaded, 2.3 kg, 4.6 kg) across the painful arc (31°–120°). The goal was to identify which specific movement and muscle-activation abnormalities actually exist in symptomatic overhead workers.
Before this paper, impingement rehabilitation often meant either generic rotator cuff strengthening or broad scapular stabilization programs — with little objective data to distinguish which muscles were actually dysfunctional.
This study gives you a specific target: serratus anterior, not the trapezius. The trapezius is already overcompensating. Adding more trapezius-dominant exercises (rows, shrugs, Y-T-W variations that load the lower trap) without first restoring serratus anterior function will not correct the anterior tipping deficit at end-range.
When you see an overhead worker with impingement symptoms, the key clinical question is not 'is the scapula moving?' but 'is the anterior acromion being elevated at end-range?' Serratus anterior drives that posterior tipping; the trapezius cannot substitute for it.
One nuance worth knowing: kinematic deficits in this population are load-dependent. A clinical exam with the arm unloaded may look normal. The breakdown appears when the patient holds a tool or weight overhead, exactly replicating their occupational exposure.