Trapezius muscle activity and body movement at the beginning and the end of a workday and during the lunch period in female office employees

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Date: Apr. 2017
From: Industrial Health(Vol. 55, Issue 2)
Publisher: National Institute of Occupational Safety and Health, Japan
Document Type: Report
Length: 7,175 words
Lexile Measure: 1420L

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Abstract: The aim of this study was to analyze the activity of the trapezius muscle and the arm acceleration during the course of a workday in office employees. It was examined if there are significant changes in trapezius muscle activity in the afternoon compared to the morning work period and relationships to the level of arm acceleration during lunchtime. Nineteen female office employees were recruited. A one hour period of the work in the morning, afternoon, and lunchtime were compared. The measures of the trapezius muscle activity and muscle rest time (TR) did not significantly differ between working in the morning (TR: median 10%; range 1%-49) or working in the afternoon (TR: median 18%; range 2%-34%). The 90th percentile of arm acceleration during lunch time significantly correlated with less trapezius muscle activity in the afternoon compared to the morning values (RT: Spearman R=0.80; p<0.01). Differences in the duration and level of trapezius muscle activity were bigger between the subjects than between different work periods or between lunchtime and work Furthermore it seems that higher arm accelerations during lunch may be beneficial in reducing trapezius activity in the afternoon compared to the morning values.

Key words: EMG, Muscle activity, Trapezius muscle, Office work, Active break


Musculoskeletal disorders (MSDs) are a big health problem in the working population (1), can lead to a significant reduction of the quality of life (2), may cause a reduced productivity at work (3,4), and lead to substantial health costs (1,5). Neck pain is one of the highly prevalent MSDs (6) and often was observed in computer employees. The one-year prevalence rate of neck pain in office employees is between 51% and 58% (7-9). Neck pain is more frequent in women than in men (7,9). According to Nordander, et al. (10) at least in women, trapezius myalgia is the most prevalent diagnosis in patients suffering from neck pain.

Several authors analyzed the activity of the trapezius muscle in office employees (11-13) and it was reported that the activity of the trapezius muscle correlates with neck pain or predicts its development (14-16). Considering workload in general, physical (17), psychosocial (18) and mental loads (19) could augment the activity of the trapezius muscle. However, a review discussing the association of various loads to neck pain (20) found for most of the analyzed factors no clear evidence. In office work, the physical load is generally known to be small. Nevertheless there is evidence that even during low-level muscle activity overexertion of single muscle fibers may occur and therefore pain may develop (15). The prevailing hypothesis explaining such a development is the so-called Cinderella-Hypothesis proposed by Hagg (21). It states that a low-level activation of long duration in the trapezius muscle can keep the same muscle fiber active over the whole time leading to overexertion and eventually neck pain may develop. Especially during static muscle activation, it was shown that single muscle fibers were active over a long time (22). In relation to computer work Zennaro, et al. (23) showed...

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Gale Document Number: GALE|A489758233