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KMID : 1151220100160010026
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Journal of Korean Academy of Orthopedic Manual Therapy
2010 Volume.16 No. 1 p.26 ~ p.36
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Comparison of Upper and Lower Trapezius Activity During Shoulder Elevation and Depression for Acute and Chronic Whiplash-associated Disorder Patients
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Kim Sang-Su
Kim Suhn-Yeop
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Abstract
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Purpose: The study compared the muscle activity and ratio of upper trapezius (UT) to lower trapezius (LT) activity between acute and chronic whiplash-associated disorder (WAD) patients.
Methods: Twelve healthy (male: 7), 14 acute WAD (male: 7), and 11 chronic WAD (male: 3) volunteers participated in this study. Electromyography using a surface EMG recorded the activity of the upper trapezius and lower trapezius of both shoulders (dominant and non-dominant) during 120° elevation when standing and shoulder depression when sitting. The testing order was selected randomly. Subjects were asked to maintain each experimental position for 5 seconds at end range. EMG activity was normalized using the maximal voluntary isometric contraction (MVIC) elicited using a manual muscle-testing technique. One-way repeated measures analysis of variance (ANOVA) was used to compare the average root mean square (RMS) value of EMG activity for each condition.
Results: The EMG activity of the dominant UT for chronic WAD subjects was significantly higher than for acute WAD subjects during 120° elevation (p<.05). The EMG activity of the dominant LT for acute WAD subjects was significantly lower than for the control group (p<.05) during 120° elevation. The EMG activity of the dominant LT for WAD patients was significantly lower than for the control group during shoulder depression (p<.05), and the chronic WAD patients scored significantly the lowest (p<.01). The dominant UT/LT for chronic WAD patients was significantly higher than the ratio for acute WAD subjects during shoulder depression (p<.05); this result was higher than for the control group (p<.01). The non-dominant UT/LT (ratio) for chronic WAD patients was significantly higher than the ratio for acute WAD subjects during shoulder depression (p<.05).
Conclusion: The UT for chronic WAD subjects was hyperactive when compared to the acute WAD subjects, and the was hypoactive for both acute and chronic patients, therefore intra-trapezius imbalance was more prevalent during shoulder depression.
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KEYWORD
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Whiplash injury, Trapezius, Shoulder elevation, Shoulder depression, Muscle ratio
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