Strength and fatigability of selected muscles in upper limb: assessing muscle imbalance relevant to tennis elbow.

Alizadehkhaiyat, Omid and Fisher, A C and Kemp, G J and Frostick, S P (2007) Strength and fatigability of selected muscles in upper limb: assessing muscle imbalance relevant to tennis elbow. Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology, 17 (4). pp. 428-36. ISSN 1050-6411

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The aetiology of tennis elbow has remained uncertain for more than a century. To examine muscle imbalance as a possible pathophysiological factor requires a reliable method of assessment. This paper describes the development of such a method and its performance in healthy subjects. We propose a combination of surface and fine-wire EMG of shoulder and forearm muscles and wrist strength measurements as a reliable tool for assessing muscle imbalance relevant to the pathophysiology of tennis elbow.


Six healthy volunteers participated. EMG data were acquired at 50% maximal voluntary isometric contraction from five forearm muscles during grip and three shoulder muscles during external rotation and abduction, and analysed using normalized median frequency slope as a fatigue index. Wrist extension/flexion strength was measured using a purpose-built dynamometer.


Significant negative slope of median frequency was found for all muscles, with good reproducibility, and no significant difference in slope between the different muscles of the shoulder and the wrist. (Amplitude slope showed high variability and was therefore unsuitable for this purpose.) Wrist flexion was 27+/-8% stronger than extension (mean+/-SEM, p=0.006).


This is a reliable method for measuring muscle fatigue in forearm and shoulder. EMG and wrist strength studies together can be used for assessing and identifying the muscle balance in the wrist-forearm-shoulder chain.

Item Type: Article
Additional Information and Comments: “NOTICE: this is the author’s version of a work that was accepted for publication in Journal of electromyography and kinesiology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of electromyography and kinesiology, [VOL#17, ISSUE#4, (August 2007)] DOI#10.1016/j.jelekin.2006.04.007¨
Keywords: Lateral epicondylitis; Electromyography; Muscle fatigue; Wrist strength
Faculty / Department: Faculty of Science > School of Health Sciences
Depositing User: Omid Khaiyat
Date Deposited: 01 May 2016 14:16
Last Modified: 01 Dec 2017 06:01

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