Articles containing the keyword 'physical stress'

A team of 2 experienced workers was time-studied and their heart rate recorded under 4 days in clearcutting of a highly self-pruned Pinus patula Schltdl. & Cham. plantation. Task work and bonus payment systems were compared, but there was no difference in production rate, only the workplace time was extended from 2.3 h/d in task work to 3.9 h/d in bonus payment. The heart rate was 115–116 P/min in felling, 105–109 P/min in debranching and 109–114 P/min in bucking. The average heart rate in timber cutting was 108–109 P/min. Work load index was 34–37%, and the workers did not show any symptoms of accumulated stress. The production rate was 3.2 m³/h, (WPT, crew), which corresponds average piecework rate, the comparable walking speed being about 6.0 km/h. There are possibilities to increase the daily task by ergonomic grounds.

The PDF includes an abstract in Finnish.

• Saarilahti, E-mail: ms@mm.unknown
• Ole-Meiludie, E-mail: ro@mm.unknown

The influence of horizontal whole-body vibration of fairly low intensity alone and combined with the mental load and motor action typical for the forest machine drive on heart rate variability (HRV), respiration rate (RR) and heart rate (HR) was studied by testing five subjects. Horizontal vibration had an influence on HR, HRV and RR. ’Control activities’ had the most influence on RR and HRV, but some influence on HR, too. ’Moving the control devices’ (motor action) gave the same response in HR as ’control activities’, but not in HRV and RR. ’Control activities’ together with ’vibration’ had a more effect on HRV and RR than these two factors singly, but not on HR. The possibilities of using these variables in field studies are discussed.

The PDF includes a summary in Finnish.

• Harstela, E-mail: ph@mm.unknown
• Piirainen, E-mail: kp@mm.unknown

The safety clothing, rubber safety boots, belt with lifting hooks and personal protectors can weight about 3 kg more than the normal work clothing including rubber boots. In order to evaluate the increase off the physical strain in logging work due to them, laboratory tests performed on tread mill were made. The physical strain increased 3–11% as estimated from heart rate and 4–8% as estimated from oxygen consumption measurements.

The PDF includes a summary in English.

• Klen, E-mail: tk@mm.unknown
• Louhevaara, E-mail: vl@mm.unknown

The concepts central to ergonomic research connected with the amount of strain caused by work was studied. A model was made to describe the process of strain. The model includes the following concepts: load or stress, human input, worker, strain, renewal of human resources, output and their hierarchical units. Based on the quality of human input, the forest work was roughly divided into two categories: (1) work demanding primarily muscle activity and (2) neuro-sensory work. In the first group, especially in cutting work, the main part of the human input is intensive consumption of muscle energy. In addition, work load causes accidents, wear of skeletal and muscular systems and processes by noise, vibrations, and climate. Correspondingly, when operating forest machines, the human input is mainly neuro-sensory functions of the central nervous system. Work load causes directly the effects of low frequency vibration and of other work conditions. The model was tested on data from research of forest work.

The PDF includes a summary in English.

• Harstela, E-mail: ph@mm.unknown

The physical strain put on forest workers and work time consumption during pulpwood cutting were compared when the bolts were stacked at the side of strip road, the strip road spacings being 15–25 m and 26–35 m, and when stacked at scattered points along the cutting strip.

When stacking at scattered points along cutting strip work time consumption was 17–21% and the heart rate 9–12% less than when stacking at the side of the strip road, strip road spacing being 15–25 m. When the strip road spacing was increased to 26–35 m, the time consumption increased by 18–30%, but the heart rate appeared unchanged. This result suggests that the forest worker compensates for increased physical strain caused by an increased stacking distance by changing his working technique and rate and by increasing the number of his breaks.

The PDF includes a summary in English.

• Valonen, E-mail: pv@mm.unknown

The aim of the study was to search for measurement methods of muscle fatigue in forest work. Lactic acid concentration of capillary blood was measured from test persons after submaximal and maximal strain tests in laboratory and during forest work. At rest the lactic acid content was affected mainly by the body dimensions and blood pressure. In a maximal strain test it was affected mainly by the age. In submaximal forest work lactic acid content concentrated below the attitude factor indicating working pace and below the body dimensions so that bigger persons had a higher lactic acid concentration than smaller persons.

The PDF includes a summary in English.

• Wuolijoki, E-mail: ew@mm.unknown