Trapezius muscle; Shoulder pain; Pain--Treatment


Objective: This study examined the effects of two ergonomic arm supports on bilateral muscle activity of the upper trapezius during pipette work on laboratory workers and university faculty and students as well as participants’ perception of productivity and discomfort.

Method: A repeated measures design was conducted at each individual’s workplace. Participants (N = 7) did an 8 minute predetermined pipette task using a static ergonomic arm support, a zero gravity dynamic arm support, and no arm support, sequenced at random. Electromyography (EMG) readings of bilateral upper trapezius, as well as perceptions of discomfort and productivity were collected for each trial condition.

Results: The static condition had statistically significantly lower mean EMG muscle activity than both the control and dynamic conditions on the dominant side. The static condition also had statistically significantly lower mean EMG muscle activity than the dynamic condition on the nondominant side. The difference of the means between the dominant and nondominant sides was statistically significantly lower for the static condition than both the control and the dynamic conditions. There were no statistically significant differences for peak EMG muscle activity or for perceptions of discomfort or productivity.

Conclusion: It was found that the use of a static arm support for pipette work can significantly decrease mean EMG muscle activity of the upper trapezius of the dominant side compared to the dynamic arm support or control condition. The static condition also offered more symmetry of EMG muscle activity during pipette work. Occupational therapists can adapt work environments to increase the efficiency of muscle activity in the shoulders of lab scientists.

First Advisor

George Tomlin, PhD, OTR/L

Second Advisor

Martins Linauts, PhD, PT

Third Advisor

Yvonne Swinth, PhD, OTR/L, FAOTA

Date of Completion

Spring 5-14-2015

Degree Type







Degree Name

Master of Science in Occupational Therapy (MSOT)

Date of Award

Spring 2015


Occupational Therapy


University of Puget Sound