Reliability of thermal readings of the skin surface over the anterior deltoid during intermittent, overhead tapping tasks

Alternative techniques to quantify exposures to risk factors to further our understanding of pathophysiological mechanisms of work related musculoskeletal disorder (WMSD) development are needed. Exploratory studies of thermal imaging indicate that it is sensitive to changes in work task demands. The objective of this study was to quantify the reliability of skin thermal readings over the anterior deltoid during an overhead task. Twenty four participants completed six test sessions of a simulated overhead tapping task common in automotive assembly. Thermal images were recorded using an infrared camera. Correlations of thermal readings between days and its relationship with subjective discomfort ratings, along with effects of duty cycle (33%, 66% and 100%), gender, and day on thermal parameters were assessed. The overall reliability of thermal rate of change between days was found to be moderate to good with a Pearson's correlation coefficient of 0.56 and an ICC of 0.72. Significant moderate correlations were also found between thermal readings and subjective discomfort ratings with a Pearson's correlation coefficient of −0.55 for the rates of changes. Duty cycle affected all the dependent variables with each duty cycle differing from the other. Gender differences were found for both temperature and discomfort rate of change.Relevance to industryThis study suggests that thermal imaging is a reliable method for assessing work task demand effects on the musculoskeletal system for the shoulder during overhead work and may be useful in assessing risk for upper extremity WMSDs.

► Thermal changes over the anterior deltoid skin surface was found to be reliable.
► Thermal readings were significantly correlated with discomfort ratings.
► Different duty cycles and gender was found to affect thermal parameters.