Determination of physical stress in agricultural work

The aim of this study was to find a method or combination of methods appropriate for defining the physical stress imposed by jobs carried out in the farm environment. Besides charting research methods, various other methods were applied to three sample jobs (making a load of bales, lowering of tomatoes and mechanised loading and transportation of timber). The sample jobs were selected to represent dynamic loading, static stress and work posture stress. The methods chosen were: oxygen consumption, pulse-blood pressure measurement, electromyography, the OWAS work posture observation method, and the Borg RPE scale for recording the test person's subjective stress estimate. The experiments were conducted using four test persons in real working environments. According to this study different methods for determining the physical stress of work are needed.The stress of dynamic work can best be investigated by means of oxygen consumption or heartbeat frequency. Furthermore, with these methods it is possible to classify jobs. The static stress can be determinated by means of the stress felt by the test person and electromyographic recordings of changes in muscle tension, although these are quite person-sensitive methods. Static stress also affects heartbeat frequency and blood pressure. The OWAS method is probably the best method available when studying the work postures in agricultural work - at least when involved in whole body work requiring moving about on the part of the person doing the job.