abstract
Background: Fatigue has a strong impact on workers’ performance and safety, but expedient methods for
assessing fatigue on the job are not yet available. Studies discuss posturography as an indicator of fatigue,
but further evidence for its use in the workplace is needed. The purpose of the study is to examine
whether posturography is a suitable indicator of fatigue in clerical workers.
Methods: Thirty-six employees (Ø 34.8 years, standard deviation ¼ 12.5) participated in postural tasks
(eyes open, eyes closed, arm swinging, and dual task) in the morning and afternoon. Position of their
center of pressure (COP) was registered using a Nintendo Wii Balance Board and commercial software.
From registered COP time series, we calculated the following parameters: path length (mm), velocity
(mm/s), anterioreposterior variance (mm), mediolateral variance (mm), and confidence area (mm2
).
These parameters were reduced to two orthogonal factors in a factor analysis with varimax rotation.
Results: Statistical analysis of the first factor (path length and velocity) showed a significant effect of time
of day: COP moved along a shorter path at a lower velocity in the afternoon compared with that in the
morning. There also was a significant effect of task, but no significant interaction.
Conclusion: Data suggest that postural stability of clerical workers was comparable in the morning and
afternoon, but COP movement was greater in the morning. Within the framework of dynamic systems
theory, this could indicate that the postural system explored the state space in more detail, and thus was
more ready to respond to unexpected perturbations in the morning.
2015, Occupational Safety and Health Research Institute. Published by Elsevier. All rights reserved