Does packing activity change worker's thermal sensitivity to local cold stimuli compared to sitting state?

Abstract

This paper focuses on the changes of cold thermal sensitivity (CTS) of people during sitting and physical working (packing while standing). Eight body parts were subjected to three cold stimulus temperatures, respectively, during the two activities. The cold stimuli sensation (CSS), local thermal sensation votes (LTSV) and overall thermal sensation votes (OTSV) were collected. During the experiments, the mean skin temperature (Tsk) and the local skin temperature of the stimulated body part (Tlsk) were recorded continuously. The CSS under physical working was significantly lower than that of sitting for most body parts. For both activities, the LTSV of the stimulated body part was reduced effectively, while the reduction of LTSV became smaller under physical working. The OTSV decreased slightly after the local cold stimuli, and the decrement was similar in both activities. Compared to sitting, the change rate of Tlsk at back, upper arm, thigh and lower leg decreased more significantly under physical working. Positive correlation between the CSS and the stimulus temperature difference (ΔT(lsk-sti)) was found. Under the same ΔT(lsk-sti), the CSS during physical working was lower than that of sitting, and the decrease of CSS at back, thigh and lower leg was more significant. Through grade grouping analysis, the eight body parts were classified based on CTS and the effect on LTSV, which indicated that the classification was different between the two activities. In conclusion, the subjects’ thermal sensitivity to local cold stimuli decreased during physical working, and the cold sensitivity of body parts also changed.