ABSTRACT
Metabolic Load Heart Rate Monitor - A good measure of overall exertion is
heart rate, which can easily be measured with simple heart rate monitors. This standard technique is well based in science and is particularly effective since the monitors are small, lightweight, and do not interfere with the employees' normal work activities. The heart rate is measured with a small patch that is worn across the chest. This patch transmits heart rate data to a small receiver that can be worn like a wristwatch or pinned to the clothing. Data from the receiver are uploaded daily into a computer and later analyzed. There are accepted guidelines for heart rate levels and exertion and this technique can, for example, help defme the relationship between workload and staffmg requirements for physically demandingjobs. Static Load
Time - Static load is measured in terms of time. The classical perspective is that of the number ofminutes it takes before the onset of pain. More recently, with the concern for highly repetitive jobs, the approach taken has been to study the percentage of time in which a single muscle group is used. (Note that awkward postures and exertion can worsen the effect of static load, but the primary index of concern is tlme.)
EMG - Electromyography can also be used to characterize fatigue. The development of local muscle fatigue has been correlated to changes in the frequency composition of EMG activity. Observing these changes requires sophisticated instrumentation and analytic techniques.
