Assessment of the Musculoskeletal Load of the Trapezius and Deltoid Muscles during Hand Activity

deltoid muscle

Stabilization of Hand Required for High Precision Tasks

During fundamental research and field research we noted the significance of a relaxed hand and forearm to operate a computer mouse. Gripping and pinching as well as reaching for the mouse showed to have severe negative effects on the upper extremity.

We require our hands to perform a great number of varying tasks with the mouse which requires high precision. Although Professor Van Zwieten, Department of Anatomy, BioMed, University of Hasselt mentions the possible risk of moving from the wrist in his paper “Hand Positions in scrolling, as related to PC-workers’ dystonia and treatment of dystonia by means of vibrostimulation and external shock waves therapy” (2009) we sometimes have to.

Danuta Roman-Liu, et al.

Higher precision requires stabilization of hand and forearm to minimize stress. It is from this perspective that we are pleased to be able to refer to the paper by Danuta Roman-Liu, et al. Department of Ergonomics, Central Institute for Labour Protection, Warsaw, Poland.

“Assessment of the musculoskeletal load of the trapezius and deltoid muscles during hand activity.” (2001). In this publication the following is mentioned:

First, higher precision of a task in which only the hand is involved, requires accuracy of movements which means more stabilization of the upper extremity and thus higher muscle tension. Furthermore, in view of the difficulty and possibly the complexity of the task a higher muscular tension can be expected.

No Effect on the Deltoid Muscle

Where is the Deltoid muscle?

The resulting muscle loads due to the performed task influences the tension of the trapezius muscle. Contrary to what is generally thought the study proves that there is no effect on the deltoid muscle.

It should be noted that the lower the level of force used, the more precise a difficult task can be executed. As a consequence, when the forearm is not supported, a higher tension of the descending part of the trapezius muscle results. We herewith refer to the paper by Professor Han Ming Chen of National Taiwan University “The effect on forearm and shoulder muscle activity in using different slanted computer mice” (2007) and our team of Erasmus University Medical Centre “Result of the use of a hand supporting computer mouse by patients with neck and shoulder complaints” (2006).

Support the forearm

So this publication proves the need to support the forearm when working with a computer mouse.

Hand Support when using a computer mouse