Context
Subacromial impingement syndrome (SIS) is associated with scapular dyskinesis, or imbalanced scapular muscle activity. Evidence has shown that feedback can improve scapular control in patients with SIS. However, it is unknown whether real-time video feedback or electromyography (EMG) biofeedback is optimal for improving scapular kinematics and muscle activity during a functional task.
Objective
To compare the effects of video and EMG feedback sessions on absolute muscle activity (upper trapezius [UT], lower trapezius [LT], serratus anterior), muscle balance ratios (UT/LT, UT/serratus anterior), and scapular kinematics (anterior-posterior tilt, external-internal rotation, upward rotation) in SIS participants during arm elevation and lowering.
Design
Randomized controlled clinical trial.
Setting
Research laboratory.
Patients or Other Participants
Overhead athletes who were diagnosed with SIS and who also exhibited scapular dyskinesis (N = 41).
Main Outcome Measure(s)
Three-dimensional kinematics and EMG were recorded before and after feedback training.
Results
Lower trapezius muscle activity increased (4.2%–18%, P < .011) and UT/LT decreased (0.56–1.17, P < .013) in the EMG biofeedback training group as compared with those in the video feedback training group. Scapular upward rotation during arm elevation was higher in the video group than in the EMG group after feedback training (2.3°, P = .024).
Conclusions
The EMG biofeedback improved muscle control and video feedback improved the correction of scapular upward rotation in patients with SIS.
Trial Registration Number
ClinicalTrials.gov: NCT03252444.
Background: Predictive variables associated with the effects of a scapular conscious control program should be identified and used to guide rehabilitation programs. Purpose: To determine whether potential factors are associated with the success of scapular muscle balance with an early control program in patients with subacromial pain and scapular dyskinesis. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 38 amateur overhead athletes with subacromial pain and medial border prominence were recruited. They performed progressive conscious control of scapular orientation during 45° and 90° of arm elevation. Stepwise logistic regression and receiver operating characteristic curve were used to determine the optimal cutoff point of related factors for success or failure of the program. Potential factors including pain level during activity, pain duration, anterior/posterior shoulder flexibility, forward shoulder posture, posterior displacement of root of spine and inferior angle, scapular kinematics, and muscle activation before conscious control program were recorded as independent variables. Successful control defined as decreases of the upper trapezius/serratus anterior ratio in 2 consecutive trials of the 90° program or failure in the program was used as a dependent variable. Results: Having a posterior displacement of the inferior angle of the scapula of ≤16.4 mm and scapular posterior tipping during arm elevation of ≤3.3° (collected before the control program) were associated with the success of the program ( R 2 = 0.286; P < .05). Additionally, participants with each or both variables present at baseline had probabilities of success of 78% and 95%, respectively. Conclusion: The value of scapular posterior displacement and posterior tilt should be considered before early scapular control program. Other factors related to the success of the program should be found due to the limited variance explained in the regression model.
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