Investigating the Use of Changes in Facial Features as Indicators of Physical Workload

OCCUPATIONAL APPLICATIONS

Physical workload may lead to negative outcomes, including musculoskeletal disorders. In this study, we found that there were observable changes in facial features over the length of a low intensity, prolonged assembly task, and that these changes were correlated to other measures of physical workload. This method can be implemented by practitioners to evaluate physical workload.

TECHNICAL ABSTRACT

Background: Understanding physical workload is essential to avoid fatigue-related errors and to minimize injury risk. However, existing measures may not always be feasible for on-site, real-time, physical workload assessment, due to intrusiveness and interruption to the workers. Purpose: Determine whether changes in facial features are related to physical workload. Methods: Sixteen participants performed an assembly task with sustained postures until exhaustion in two separate sessions. Independent variables were time (first and last data window) and session. Dependent variables were ratings of perceived exertion (RPEs), electromyography (EMG), percent of heart rate reserve, and changes in facial features. Results: The sum of the movement path and distance of all selected facial landmarks in the regions of the eye, eyebrows, mouth, chin, and head increased significantly from the start to the end of the task. These features were significantly and positively correlated with other physical workload measures, such as RPEs, EMG, and percent of heart rate reserve. Conclusions: The observable facial changes related to physical workload are potential non-intrusive and non-disruptive indicators of physical workload.

Keywords:

• Facial features
• physical workload
• physiological measurement
• assembly
• video-based assessment

Conflict of Interest

There was no potential conflict of interest reported by the authors.