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In-chair movement: validity, reliability and implications for measuring sitting discomfort
P A Fenety1, C Putnam, J M Walker
1School of Physiotherapy, Dalhousie University, Halifax, Nova Scotia, Canada. anne.fenety@dal.ca
Applied Ergonomics
|September 7, 2000
Summary
This study developed a continuous, objective method to measure sitting discomfort using an interface pressure mat to track center of pressure (COP) and in-chair movement (ICM). Averaging ICM samples proved reliable for assessing dynamic sitting discomfort in operators.
Area of Science:
- Ergonomics
- Human-Computer Interaction
- Biomedical Engineering
Background:
- Traditional sitting discomfort assessment relies on subjective scales and static objective measures.
- The dynamic nature of sitting discomfort necessitates continuous, objective measurement methods.
- Existing methods fail to capture the real-time variations in discomfort experienced during prolonged sitting.
Purpose of the Study:
- To adapt an interface pressure mat for continuous measurement of in-chair movement (ICM) as an objective correlate of sitting discomfort.
- To validate the system's accuracy in laboratory settings and establish its reliability in field conditions.
- To develop a reliable data sampling protocol for ICM data collection.
Main Methods:
- Developed a system using an interface pressure mat to track the center of pressure (COP) at the buttock-chair interface, quantifying ICM.
- Validated the system in a laboratory setting by comparing mat-derived ICM with force platform data (r2 > 0.80) and gross trunk movements (r2 > 0.86).
- Assessed field reliability with telecommunications operators over 2-hour tests, employing intraclass correlation coefficients to determine optimal data sampling protocols.
Main Results:
- Laboratory validation confirmed a strong correlation between the pressure mat system and established measurement tools.
- Field studies demonstrated that averaging multiple 5-minute ICM samples provided more reliable data than single discrete samples.
- ICM significantly increased over the 2-hour sitting period, indicating accumulating discomfort, with no significant difference between trials.
Conclusions:
- The adapted interface pressure mat system provides a valid and reliable method for continuously measuring ICM as an objective indicator of sitting discomfort.
- A data sampling protocol involving averaging multiple 5-minute ICM samples enhances reliability for field studies.
- Continuous ICM monitoring offers a promising approach for understanding and mitigating sitting discomfort in occupational settings.