Forearm extensor and flexor muscle exertion during simulated gripping work -- an electromyographic study.

OBJECTIVE: To study forearm muscular exertion during intermittent gripping work at three different regimes resembling vocational work. DESIGN: An electromyographic laboratory study of forearm fatigue during intermittent gripping work at 25% MVC with 10/10, 20/10 and 30/10 s of work/rest was performed. BACKGROUND: Data from the literature indicate that forearm flexors as well as extensors are activated during gripping. However, no systematic quantitative assessment of the muscular exertion has been made hitherto. METHODS: Nine female subjects participated. EMG was detected from five forearm muscles, three extensors and two flexors. Zero crossing rate alterations were used as an index of fatigue. RESULTS: The results show significant (P < 0.05) fatigue signs in at least two of the extensor muscles at all regimes while significant signs of fatigue was seen only at the 30/10 regime for the flexor muscles. CONCLUSIONS: Fatigue effects are generally larger on the extensor side. None of the studied regimes is acceptable from EMG fatigue point of view. RELEVANCE: The muscular fatigue of the forearm extensors in relation to the flexors during gripping work has not been systematically assessed before. Forearm fatigue distribution is probably of great importance for the understanding of forearm disorders related to muscular exertion.

[1]  G. Hägg Electromyographic fatigue analysis based on the number of zero crossings , 1981, Pflügers Archiv.

[2]  Å. Kilbom,et al.  Repetitive work of the upper extremity: Part II — The scientific basis (knowledge base) for the guide , 1994 .

[3]  R Kadefors,et al.  Tool design, user characteristics and performance: a case study on plate-shears. , 1993, Applied ergonomics.

[4]  G M Hägg,et al.  Forearm muscular load and wrist angle among automobile assembly line workers in relation to symptoms. , 1997, Applied ergonomics.

[5]  C. Snijders,et al.  Provocation of epicondylalgia lateralis (tennis elbow) by power grip or pinching. , 1987, Medicine and science in sports and exercise.

[6]  M Hagberg,et al.  Muscular endurance and surface electromyogram in isometric and dynamic exercise. , 1981, Journal of applied physiology: respiratory, environmental and exercise physiology.

[7]  R. Kadefors,et al.  An electromyographic index for localized muscle fatigue. , 1977, Journal of applied physiology: respiratory, environmental and exercise physiology.

[8]  D B Chaffin,et al.  A methodology for documenting hand positions and forces during manual work. , 1979, Journal of biomechanics.

[9]  J Malchaire,et al.  Evaluation of handgrip force from EMG measurements. , 1995, Applied ergonomics.

[10]  C Fransson-Hall,et al.  Characteristics of forearm-hand exposure in relation to symptoms among automobile assembly line workers. , 1996, American journal of industrial medicine.

[11]  G M Hägg,et al.  Relations between shoulder/neck disorders and EMG zero crossing shifts in female assembly workers using the test contraction method. , 1987, Ergonomics.

[12]  G. Hagg,et al.  Interpretation of EMG spectral alterations and alteration indexes at sustained contraction. , 1992 .

[13]  S. Siegel,et al.  Nonparametric Statistics for the Behavioral Sciences , 2022, The SAGE Encyclopedia of Research Design.