Physical Demand, Fatigue and Shift Work in the Installation and Maintenance of Window Air-Conditioner Units

摘要

The goal of the current study was to investigate the effects of the physical workload involved in manually lifting, repairing and maintaining window air conditioner units on perceived fatigue as well as the impact of shift work. The relationships among objective and subjective measures of perceived physical demand and fatigue in an actual heavy workload task setting were analyzed. The study considered 88 skilled male workers (aged 26–40) employed in window air-conditioner maintenance workshops. In this study, two objective measures were used, heart rate (HR) and energy expenditure (EE), to evaluate the levels of energy required and fatigue. Subjective assessment tools were used, with the Swedish Occupational Fatigue Inventory (SOFI) employed to rate perceived fatigue. The NASA-TLX subjective tool was used to evaluate the overall demand, whereas Borg-CR10 was used to measure the perceived physical demand. The results indicate that the HR and EE significantly increased when the workers lifted air-conditioner units, and the subjective assessment scores increased as well. Workers perceived the highest overall workload and fatigue levels during the night work shift, as reflected in the higher scores for the SOFI parameters during that shift. The correlations among objective and subjective measures were significant. The SOFI parameters (lack of energy and lack of exertion) and the NASA-TLX and Borg-CR10 measures were positively correlated with HR. EE was positively correlated with the SOFI parameters, except for the lack of motivation parameter, and the NASA-TLX and Borg-CR10 scales. Significant relationships among the subjective tools of the SOFI, NASA-TLX and Borg-CR10 scales were found. Therefore, the SOFI technique is a useful and valid method to evaluate fatigue levels in tasks performed in occupational work.