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Energy expenditure and working efficiency of South African sugarcane cutters

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dc.contributor.advisor Coetsee, M.F.
dc.contributor.advisor Davies, S.E.H
dc.contributor.author Muller, Marie de Lanoy
dc.date.accessioned 2010-06-17T10:16:38Z
dc.date.available 2010-06-17T10:16:38Z
dc.date.issued 2005
dc.identifier.other 305368
dc.identifier.uri http://hdl.handle.net/10530/328
dc.description Submitted in fulfilment of the requirements for the Degree of Master of Science (Human Movement Science) in the Faculty of Science and Agriculture at the University of Zululand, 2005. en_US
dc.description.abstract This study sought to examine the physiological demands as well as selected measures for working efficiency in the manual harvesting of burnt and unburnt sugarcane, along with the effects of using a short handle curved blade knife and a long handle curved blade knife on energy expenditure and working efficiency. The effect of subject observation and unobtrusive observation interaction on the cane cutters' performance was also investigated. A total of fifteen professional male cane cutters participated with written informed consent. Only cane cutters with five or more years' working experience were randomly selected to participate in this study. Research in the field of sugarcane cutters in South Africa has been restricted to estimates of energy expenditure only. Evidence shows that heart rate and oxygen uptake during an actual activity differ from measurements in the laboratory at equal workloads. With this in mind, oxygen uptake and energy expenditure were measured directly by means of indirect calorimetry, during the performance of work. The metabolic measures were measured by means of the portable MetaMax 1 Ergospirometry System. Heart rate was measured telemetrically by means of the Polar Accurex Plus™ wrist receiver and its Polar Pacer transmitter. After data collection, heart rate data were downloaded via a Polar Interface Plus with Training Advisor Software onto a computer, and analysed. For the effects of unobtrusive observation interaction on the cane cutters' performance average heart rate during cane harvesting was related to the oxygen consumption, measured by the MetaMax I, using the corresponding heart rate. From this, the energy expenditure was estimated. Burnt and unburnt sugarcane Findings indicated significant differences (p<0.05) between harvesting burnt and unburnt sugarcane with regard to the following physiological parameters: absolute oxygen consumption (p<0.01) and relative oxygen consumption as well as absolute and relative energy expenditure. The mean and peak heart rates during work were not significant (p>0.05), indicative of similar levels of exertion for harvesting burnt and unburnt cane. Ratings of perceived exertion (RPE) did not differ significantly (p>0.05), suggesting that the subjective perception of exertion of harvesting burnt and unburnt cane was similar. The selected measures for working efficiency were as follow: Rate of productivity harvesting burnt cane was significantly higher (p<0.01) than that for unburnt cane. Significantly less energy was required to cut one kilogram of burnt cane than that for unburnt cane. The amount of burnt cane cut per litre of oxygen consumed was also significantly higher (p<0.01) than in harvesting unburnt cane. The number of cane cutting strokes per minute to cut the stalks of burnt cane was significantly higher (p<0.05) than that for unburnt cane while the number of stalks cut per stroke for burnt cane was significantly lower (p<0.05) than that for unburnt cane. Despite the last two measures of working efficiency being in favour of unburnt cane, the results in general lend credence to the fact that harvesting burnt cane was more economical with regard to physiological parameters and selected measures of the working efficiency of the cane cutters. Manual sugarcane harvesting implements No significant differences (p>0.05) were demonstrated for the comparison between the short handle curved blade knife and the long handle curved blade knife in burnt cane in any of the measured variables for the physiological parameters, except for the cane cutters' ratings of perceived exertion (RPE). This suggests that the cane cutters' subjective perception of strain experienced harvesting burnt cane with the short handle curved blade knife was more strenuous than using the long handle curved blade knife. Though the selected measures for working efficiency for the comparison of the short handle curved blade knife with the long handle curved blade knife did not significantly differ (p>0.05), the following measures were all in favour of using the long handle curved blade knife: Rate of productivity, energy required to cut one kilogram of burnt cane, similar amounts of cane were cut per litre of oxygen consumed, number of cane cutting strokes per minute to cut the stalks, and number of stalks cut per stroke. Subject observation and unobtrusive observation interaction The effect of observation and unobtrusive observation interaction on the cane cutters' physiological system during cane harvesting revealed significant differences (p<0.05) in corrected measures for relative oxygen consumption and relative energy expenditure. Mean heart rate responses were also significantly higher during subject observation interaction. AH remaining physiological parameters were statistically insignificant (p>0.05). The rate of productivity of the cane cutters recorded during observation interaction was significantly higher (p<0.05). Other selected measures for the working efficiency, though not statistically different (p>0.05) were also higher during subject observation compared with the experimental condition of unobtrusive observation interaction. These results show that subject observation interaction leads to increases in the performance of the cane cutter. en_US
dc.description.sponsorship University of Zululand en_US
dc.language.iso en en_US
dc.subject Sugar workers--Psysiology--South Africa en_US
dc.title Energy expenditure and working efficiency of South African sugarcane cutters en_US
dc.type Thesis en_US


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