Physiological and psychophysical responses to static, dynamic and combined arm tasks

The main objective of the present study was to determine the effects of arm tasks possessing varying degrees of static and dynamic components upon the physiological and psychophysical strain imposed on the human body. Heart rate and blood pressure were used as indices of cardiovascular strain, while ratings of perceived exertion and endurance time are used as indices of psychophysical strain. For each weight of load studied, static tasks recorded the highest systolic blood pressure, dyastolic pressure, and ratings of perceived exertion values followed by combined, then highly dynamic, tasks. The highly dynamic task recorded the highest endurance time followed by combined then purely static tasks. This study supports the idea that blood pressure should be incorporated as one of the monitored strain factors in setting criteria for manual materials-handling tasks. In addition, the ratings of perceived exertion can be used as an effective tool in assessing the static component of the task. Based on the results obtained from the experimental conditions studied, the weight of the load has been shown to be an important parameter in the design of arm tasks comprising varying degrees of static and dynamic components. On the other hand, the frequency of handling is not an important parameter in the design of these types of tasks.