Title page for ETD etd-09112001-235340

Type of Document Master's Thesis
Author Stanfield, Jennifer Renee
Author's Email Address jstanfie@vt.edu
URN etd-09112001-235340
Title Identification and Quantification of Workstation Set Up on Risk Factors Associated with the Development of Low Back and Neck Discomfort
Degree Master of Science
Department Industrial and Systems Engineering
Advisory Committee
Advisor Name Title
Babski-Reeves, Kari L. Committee Chair
Kleiner, Brian M. Committee Member
Nussbaum, Maury A. Committee Member
  • Chair Type and Chair Type
  • Workstation Design
  • Back and Neck Discomfort
  • Video Display Terminals
  • Monitor Height
Date of Defense 2001-07-23
Availability unrestricted
Identification and Quantification of Workstation Set Up on Risk Factors

Associated with the Development of Low Back and Neck Discomfort

Jennifer R. Stanfield


Work related musculoskeletal disorders (WMSD) remain the focus of research efforts as

costs associated with these disorders range from 13 to 54 billion dollars annually.

WMSDs associated with the back and neck compromise almost 27% of all reported

WMSDs. Approximately 1/3 of visual display terminal (VDT) operators report back and

neck pain annually (BLS, 1998). Physical risk factors of VDTs associated with low back

and neck WMSDs include static work postures and workstation design. The objectives of

this study were to assess the effects of monitor height, chair type and their interaction on

task performance, back/neck electromyography (EMG), perceived discomfort, and

number of posture shifts. Both monitor height and chair type were assessed using two

levels (high and low). Participants, four male and four female college age students,

performed two data entry tasks using a standard keyboard and monitor and a fully

adjustable bi-level table. In addition to the experimenter defined workstation

configurations, participants were allowed to adjust their workstation to their preferred

settings. Analysis of variance was performed to assess differences in task performance,

perceived level of discomfort, number of posture shifts, and EMG data associated with

various combinations of monitor height and chair type. Correlation analysis was

performed to assess the relationship between participant's perceived discomfort and

measured muscle activity to help determine if these two measurements could be used

interchangeably to assess workstation design.

No effect of workstation configuration (monitor height/chair type) was found for the

majority of dependent variables. An exception was that configuration of low monitor,

high chair, and their interaction generated significantly more muscle activity for the low

back. User preferred settings were not found to differ significantly from those

investigated with respect to muscle activity, perceived discomfort, posture shifts, and

performance. Additionally, it was found the participants chose to position the iii

workstation according to guidelines suggested in the literature for reducing WMSD


Task effects were found for performance, posture shifts, and perceived level of

discomfort. Higher levels of performance and posture shifts for the neck were associated

with the typing task, as opposed to the math task. Higher levels of neck discomfort,

posture shifts of the feet and posture shifts of the back were associated with the math


Correlation analysis provided evidence that perceived discomfort reported by participants

and muscle activity for job tasks may not be related. Observed muscle activity for the

tasks investigated in this study was low and in some instances, close to resting activity.

Due to low levels of EMG, participants may not have been cognizant of their back and

neck muscle activity, offering an explanation for why participants experience a

cumulative effect of workstation design and seated postures, but linking particular causal

factors to the development of LBP and NP is difficult.

The findings of this study suggest that there are no gross physical differences between the

chair types or monitor heights as defined in this study. Other factors (such as user

preferences, job task demands, specific chair parameters, etc.) may significantly effect

chair selection. This study found that task was a significant effect for the majority of

dependent variables, and therefore may need to be a major factor driving workstation

design. Workstation configuration will help determine the type of static posture assumed

at a workstation, but the "discomfort or number of posture shifts" associated with that

workstation and posture might be more a result of the job task requirements.

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