The Immediate Effect of Exercise with/without EMG Biofeedback in Subjects with Subacromial Impingement Syndrome: Muscle Activity Pattern and Scapular kinematics
Date Issued
2011
Date
2011
Author(s)
Huang, Han-Yi
Abstract
Background: Muscle imbalance between searratus anterior and trapezius muscles as well as scapular dyskinesis have been observed in subjects with shoulder disorder such as impingement syndrome. Previous studies indicate that the muscle imbalance of scapular muscle can result in abnormal scapular motion and may contribute to further damage of impingement. In clinics, physical therapists usually use strengthening exercises to restore proper scapular muscle balance and motor control in patients with subacromial impingement syndrome (SAIS). Electromyography (EMG) biofeedback technique is believed to allow subjects to learn how to control the activities of stabilizers/force couples and to enhance motor program training. Objective: The purposes of this study are (1) to investigate the effect of EMG biofeedback training on muscle balance ratios during exercises in healthy adults and subjects with SAIS; (2) to investigate whether the effects of EMG biofeedback on muscle balance ratios are different between healthy adults and subjects with SAIS (3) to investigate the immediate effect of EMG biofeedback training on scapular kinematics in healthy adults and subjects with SAIS. Design: Twelve healthy adults and thirteen subjects with SAIS were recruited in this study. 3-D electromagnetic motion analysis and EMG muscle activity were used to record the scapular kinematics and muscle balance ratios during exercises with and without EMG biofeedback. The scapular kinematics were also recorded before and after exercises with/without EMG biofeedback. Main outcome measures: The balance ratios (UT/LT, UT/MT and UT/SA) and scapular kinematics (scapular upward/downward rotation, anterior/posterior tipping) were outcomes of this study. Result: For the subjects with SAIS, the lower muscle balance ratios were found when the subjects performed the forward flexion exercises with EMG biofeedback than exercise only (UT/SA: 70.3- 45.2; UT/LT: 124.8- 94.6). Additionally, the similar results were found in the side-lying external rotation (UT/MT: 58.5- 36.4). For the kinematics, there were non-significant differences between exercise and exercise with biofeedback in change scores of upward rotation and tipping angle in both groups. Conclusion: Results illustrated the potential of EMG biofeedback for restoring the scapular muscular balance during the forward flexion and side-lying external rotation exercises in both groups. Based on our results, we suggest the use of EMG biofeedback combined with the strengthening exercise to promote the scapular muscle balance. Further clinical trial should investigate the short-term and long-term effects of EMG biofeedback.
Subjects
subacronmial impingement syndrome
muscle control
EMG biofeedback
serratus anterior
trapezius
Type
thesis
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