Effects of incremented loads over preferred values on psychophysical and selected gait kinematic factor
- Authors: Manley, Peter Gwynne
- Date: 1989
- Subjects: Psychophysiology , Kinematics , Work -- Physiological aspects , Human engineering
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:5160 , http://hdl.handle.net/10962/d1015734
- Description: This study investigated the effects of incremented loads greater than maximal acceptable loads on selected locomotor kinematic and psychophysical variables for four different hand-held load-carriage methods. Ten male and ten female subjects, between the ages of 18 and 30, participated in four experimental sessions. Data collection involved obtaining selected anthropometric, strength, maximal load and preferred load, gait kinematic, and psychophysical values. The anthropometric, strength and load capacity variables enabled absolute and morphology normalised sex-based comparisons to be made. The kinematic and psychophysical parameters were used to quantify any changes from two sets of baseline values,"unloaded" and "maximal acceptable load" values, when loads were increased and carrying methods changed. Statistical analysis revealed that males were taller, heavier and stronger than females (p<0.05). Males chose significantly greater maximal acceptable loads and absolute maximal loads than females when expressed in their absolute or relative terms. Preferred walking speeds were not significantly different for unloaded or loaded conditions, although males walked significantly faster in absolute terms (but not in relative terms) than females. Different load carrying methods and incremented loads brought. about significant changes to several of the kinematic parameters investigated. Finally, ratings of perceived exertion, as well as the number of exertion sites, were seen to increase significantly as load increased. These values were not, however, significantly affected by differences in load carriage method.
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Energetic and kinematic responses to morphology-normalised speeds of walking and running
- Authors: Williams, Martin Andrew
- Date: 1989
- Subjects: Running -- Physiological aspects , Walking -- Physiological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5166 , http://hdl.handle.net/10962/d1016240
- Description: This study investigated the influence of human morphology upon selected physiological, biomechanical and psychological responses to horizontal locomotion. In so doing, it was possible to evaluate the effectiveness with which morphology-normalised speeds of walking and running reduced the between-subject variability that is inherent in human locomotor responses. Twenty caucasian males were divided into two groups on the basis of stature - ten subjects in each of a "short" category (<170cm) and a "tall" category (>185cm). All subjects were habituated to treadmill locomotion prior to exposure to three walking treatments (0.83, 1.39 and 1.94m.s⁻¹) and three running treatments (2.50, 3.06 and 3.61m.s⁻¹). During each of these five-minute locomotor conditions, energetic (V02), kinematic (cadence and stride length) and psychophysical (central and local RPE) data were captured. From these data, lines of best fit were calculated for each subject, allowing for a prediction of the abovementioned locomotor variables from known absolute rates of progression. Using suitable regression equations, subject responses to morphology-normalised speeds of walking and running were effectively extrapolated. When the rate of progression was expressed in absolute terms (m.s⁻¹), significant differences (P <0.05) were found between the stature-related groups with respect to both energetic and kinematic locomotor responses. Such differences were successfully eliminated when use was made of locomotor speeds relativised on the basis of morphology. This study concludes that the use of appropriately prescribed morphology-normalised rates of progression are effective in reducing the variability in locomotor responses between subjects differing significantly in stature.
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Identification and analysis of manual materials handling tasks within a commercial warehouse in South Africa
- Authors: Walraven, Lynne Louise
- Date: 1989
- Subjects: Materials handling -- Safety measures , Industrial safety -- South Africa , Lifting and carrying -- Safety measures
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:5159 , http://hdl.handle.net/10962/d1015722
- Description: Lifting and overstraining are major causative factors related to musculoskeletal injuries and low back pain. A great number of work-related injuries arise from the handling and/or mishandling of materials. Hence there is a need to quantify risk factors in situ and develop guidelines for safe lifting practises in industry. The aim of this study was to make appropriate in situ quantification, within a commercial warehouse, of the stresses and physical demands imposed on the worker when performing two handed lifts in the sagittal plane. The performance of employees was assessed under normal working conditions through an observational methodology of data collection. Task performance evaluation was based on detailed measurement of all containers handled, an activity and time analysis, and the 'Work Practices Guide to Manual Lifting’ (NIOSH, 1981) which was used as the primary guide to developing theoretical recommendations to probable MMH risk factors for the workers involved. Of the 191 tasks analysed 103 were deemed unsuitable. Appropriate task factor adjustments were made where necessary to both the frequency and Hfactors (horizontal distance between the centre of gravity of the container and that of the worker) in order to reduce the risk factor for the workers
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Physiological and psychophysical factors in the rating of perceived exertion during uphill overground and treadmill running
- Authors: Olivier, Stephen Chris
- Date: 1989
- Subjects: Physical fitness -- Measurement , Physical fitness -- Physiological aspects , Physical fitness -- Psychological aspects , Running -- Testing
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:5161 , http://hdl.handle.net/10962/d1015769
- Description: The purpose of this study was to examine possible differences between the field and laboratory ratings of perceived exertion (RPE) when the performance and physiological measures for the two conditions were equated. Furthermore, the interactive effects of local, central and overall RPE were examined. Finally, the question of the potential effects of attitudes on RPE was addressed. Eleven well-conditioned adult male marathon runners voluntarily participated in the study. After a period of treadmill habituation, biographical and anthropometric data were collected. This was followed by a VO₂ max test and a speed-matching session at 70% of VO₂ max to determine overground running speed at 3.8% and 7. 5% grade. Subjects then completed an attitudinal questionnaire and ran 4km overground. Finally, the above test was repeated on the treadmill, with the gradient and running speed of the overground condition being replicated. Physiological measures and differentiated RPE were obtained during the final two sessions. There were no physical environmental, task characteristic or performance differences between the overground and treadmill conditions. No heart rate or VO₂ differences were observed between the two conditions, but VE was significantly elevated in the laboratory. Local and overall RPE were significantly higher in the laboratory than in the field, but there was no difference for central RPE. Attitudes were more favourable towards the field than towards the laboratory work task. The results suggest that neither heart rate nor VO₂ are major factors directly influencing the perception of exertion. VE however appears to be a potent central signal mediating RPE. The results also indicate that local factors play a more important role in the perception of exertion than was previously thought. Attitudes towards a work task could possibly mediate the self-reports of exertion. The findings of this study also suggest that RPE are influenced by cognition to a large degree. Finally, environmental cues, or the ambience of a particular working environment, can exert a substantial influence on RPE. Direct perceptual translations from laboratory to field situations may therefore be invalid.
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The effects of a South African Black youth jive on selected biophysical physiological and psycho-social parameters
- Authors: Masipa, Mochaki Deborah
- Date: 1989
- Subjects: Movement, Psychology of , Dance, Black -- Physiological aspects , Dance -- Physiological aspects
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:5158 , http://hdl.handle.net/10962/d1015682
- Description: This study investigated the effects of a South African Black youth jive on selected Biophysical, Physiological and Psycho-social parameters, using 31 Black youths, males and females (mean age 19.29 yrs) as subjects. All subjects participated in the pre- and post-programme testing protocols (acting as their own control) and in a 7-week jive programme. While the female subjects were significantly (p<0.05) heavier with a greater percentage body fat than their male counterparts, a two factor analysis of variance revealed no significant changes in body composition (p<0.05) of either sex group. However, significant improvements did occur in the cardio-respiratory . parameters of working and recovery heart rates, predicted V0₂ max, and the anaerobic capacity. Here, the males exhibited superior cardio-respiratory qualities and performed better in all motor fitness parameters except flexibility, where no significant sex difference occurred. Also, there were significant improvements in all motor fitness tests with the exception of power (as tested in the 18-Item Illinois test). No significant differences occurred between male and female psycho-social responses with no changes occurring after the 7- week programme. It can be concluded that involvement in the 7-week jive programme improved physiological parameters but failed to bring about alterations in the biophysical and psycho-social domains..
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