Comparison of the physiological cost of two motor-manual techniques for harvesting random length pulpwood

Summary

The ‘traditional’ and ‘bench’ techniques for felling pulpwood were evaluated using the same three subject fallers on both occasions. Data were collected over a four hour trial of each technique on two separate days followed by a one hour simulation of separate job elements on each day. Three out of the six elements in the job emerged as critical in discriminating between the two techniques. With the bench technique, the greatest benefit was obtained when stacking, where the average energy output of the subjects was less than with the traditional technique. These results were confirmed by measurements of utilization of maximum oxygen uptake (VO₂ max.).

When rated according to the British Medical Association's (BMA) standards on levels of physical effort at work, both techniques were classed in the category of very heavy physical effort. The level for the traditional method was higher than that for the bench technique. Analysis of physiological cost by heart rate measurements supported the energy consumption conclusions. An expected decrease in static load with the bench technique as measured by the Borsky Index was not found.

The bench technique is recommended for second thinning and random-length operations in terrain of slope up to 7° because of the reduced long-term physiological cost to the faller.