Normalization of surface EMG amplitude from the upper trapezius muscle in ergonomic studies — A review

Surface electromyographic (EMG) amplitude from the upper trapezius muscle is widely used as a measure of shoulder-neck load in ergonomic studies. A variety of methods for normalizing EMG amplitude from the upper trapezius (EMGamp ut) have been presented in the literature. This impedes meta-analyses...

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Bibliographic Details
Published in:Journal of Electromyography and Kinesiology 1995-12, Vol.5 (4), p.197-226
Main Authors: Mathiassen, S.E., Winkel, J., Hägg, G.M.
Format: Article
Language:English
Subjects:
Biomechanics
Electromyography
Occupational
Repeatability
Shoulder-neck
Terminology
Validity
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Summary:Surface electromyographic (EMG) amplitude from the upper trapezius muscle is widely used as a measure of shoulder-neck load in ergonomic studies. A variety of methods for normalizing EMG amplitude from the upper trapezius (EMGamp ut) have been presented in the literature. This impedes meta-analyses of, for instance, upper trapezius load in relation to development of shoulder-neck disorders. The review offers a thorough discussion of different normalization procedures for EMGamp ut. The following main issues are focused: output variable, location of electrodes, posture and attempted movement during normalization, load and duration of reference contractions, signal processing and test-retest repeatability. It is concluded that translations of EMGamp ut into biomechanical variables, for example relative force development in the shoulder or in the upper trapezius itself, suffer from low validity, especially if used in work tasks involving large and/ or fast arm movements. The review proposes a standard terminology relating to normalization of EMGamp ut and concludes in a concrete suggestion for a normalization procedure generating bioelectrical variables which reflect upper trapezius activation.
ISSN:1050-6411
1873-5711
DOI:10.1016/1050-6411(94)00014-X