This RCT compared two single-session feedback interventions in 41 overhead athletes with subacromial impingement syndrome and scapular dyskinesis. One group received real-time video feedback of scapular position; the other received EMG biofeedback targeting the UT/LT muscle balance ratio. The study asked which modality better corrects the kinematic and neuromuscular deficits underlying impingement.
The two deficits in scapular impingement — poor muscle activation balance and abnormal kinematics — do not always respond to the same training stimulus.
EMG biofeedback is the better tool when the patient's primary problem is a high UT/LT ratio (dominant upper trapezius, underactive lower trapezius). It trains selective muscle recruitment, but that improved recruitment does not automatically produce corrected scapular motion.
Video feedback addresses the kinematic deficit more directly: when the patient sees their scapular winging in real time, they achieve greater upward rotation and reduced internal rotation during elevation — the two kinematic abnormalities most directly linked to subacromial impingement mechanics.
For clinical decision-making, match the modality to the deficit. An athlete whose 3D kinematics show deficient upward rotation is a better candidate for video feedback. An athlete whose EMG assessment shows a persistently elevated UT/LT ratio is a better candidate for EMG biofeedback.
One session is not enough for durable change. Both modalities produced immediate retention, but serratus anterior control partially eroded after feedback was withdrawn — plan for a multi-session program, not a single neuromuscular re-education appointment.
This RCT compared two single-session feedback interventions in 41 overhead athletes with subacromial impingement syndrome and scapular dyskinesis. One group received real-time video feedback of scapular position; the other received EMG biofeedback targeting the UT/LT muscle balance ratio. The study asked which modality better corrects the kinematic and neuromuscular deficits underlying impingement.
The two deficits in scapular impingement — poor muscle activation balance and abnormal kinematics — do not always respond to the same training stimulus.
EMG biofeedback is the better tool when the patient's primary problem is a high UT/LT ratio (dominant upper trapezius, underactive lower trapezius). It trains selective muscle recruitment, but that improved recruitment does not automatically produce corrected scapular motion.
Video feedback addresses the kinematic deficit more directly: when the patient sees their scapular winging in real time, they achieve greater upward rotation and reduced internal rotation during elevation — the two kinematic abnormalities most directly linked to subacromial impingement mechanics.
For clinical decision-making, match the modality to the deficit. An athlete whose 3D kinematics show deficient upward rotation is a better candidate for video feedback. An athlete whose EMG assessment shows a persistently elevated UT/LT ratio is a better candidate for EMG biofeedback.
One session is not enough for durable change. Both modalities produced immediate retention, but serratus anterior control partially eroded after feedback was withdrawn — plan for a multi-session program, not a single neuromuscular re-education appointment.