Document Type


Date of Award

Summer 8-31-2012

Degree Name

Master of Science in Occupational Safety and Health Engineering - (M.S.)


Mechanical and Industrial Engineering

First Advisor

Arijit K. Sengupta

Second Advisor

Athanassios K. Bladikas

Third Advisor

George W. Olsen


A study was conducted to evaluate the effect of shoulder muscle activation during hand exertion tasks using a light weight hand tool by working individuals. Electromyography (EMG) of trapezius, supraspinatus, triceps, and pectoralis major was conducted for 45°, 0° and -45° arm angles, for three different reaches i.e. normal, maximum and extreme and three different push forces low, medium and high. Ten volunteers participated in the experimental study. The effects of push force and reach distance were found to be statistically significant for all four muscles. However the effect of change of angle was not found to be statistically significant, except for triceps. The only interaction effect that was found to be significant was between force and reach for all four muscles.

The interaction effect between force and reach shows higher trapezius and supraspinatus activity at low force and extreme reach levels and hence shows that the postures which require lower forces and farther reach levels are potentially more likely to cause or enhance injuries in shoulder muscles. This study for the first time used a shoulder and arm muscle activation pattern for manual tasks with a downward push force and it is relevant to the work in medical imaging sonography.