Portal de Periódicos da CAPES

Physiological cost of horizontal materials handling while seated

1992; Elsevier BV; Volume: 9; Issue: 4 Linguagem: Inglês

10.1016/0169-8141(92)90063-6

1872-8219

Helmut Strasser, Josef Ernst,

Advanced Sensor and Energy Harvesting Materials

Experiments were carried out in the course of which during seated work a load of 2 kg had to be lifted repeatedly 24 times per minute from 3 different beginning points within the outward reach over a distance of 38 cm to a fixed point near the body. In order to measure the physiological cost strictly due to unweighted movements, identical tasks had been performed by handling an almost weightless article (i.e. 0 kg). Besides oxygen consumption and heart rate as integral measures for stress and strain, electromyographic activity (EA) of 7 muscle groups was registered continuously from each of 11 subjects participating in the test sessions. EA was standardized with the help of EA-values obtained from preceding maximum voluntary contractions (MVC). The results show extensive and consistent reactions of the global and local indicators of strain. Dependent on direction, even manual movements without external load induced strain, elucidated in significant minimum values of all parameters at 30° (measured from the frontal plane of the subjects). The local strain of the 7 monitored muscles shows a more or less distinct dependence of the direction. Almost only the dynamic component is influenced, yet to a degree which is much higher than the reaction of the integral physiological parameters. Correlations between EA-values and those of the oxygen consumption as well as the work pulses indicate that electromyography is an efficient method for determining local muscular strain, which can be assessed very precisely. Furthermore, multi-channel electromyography proved to enable detection of bottle-necks in muscular strain.