The purpose of this study was to examine the concept of "critical time" (i.e. the time required to achieve steady-state heart rates) in the administration of the PWG 170 three-stage submaximal bicycle ergometer test. Specifically, the problem involved determining the effects of four different work load duration protocols on 'D' scores (which reflected the relative attainment of steady-state heart rates) and on PWG 170 scores. The combined effect of the order and relative intensity of the work loads on the 'D' scores was also studied, as was the effect of state of training on both 'D* scores and PWG 170 scores. Eight endurance-trained and eight untrained college males, aged 18 to 30, took a preliminary test to verify placement into their groups and to determine work loads for the experimental study. Each subject then underwent four experimental PWG 170 tests. Each test consisted of three periods of bicycle ergometer work of increasing intensity with the duration of the work period set at 3, 4, 5, or 6 minutes for the four test variations. There was an interval of at least two days between tests, which were administered in a counterbalanced Latin-square design. The pedalling cadence on the Monark bicycle ergometer was 50 r.p.m., and the warm-up consisted of ‘0’ work load for two minutes. Continuous monitoring of the subject's E.K.G. permitted calculationsoffaverage heart rate for every 15-second interval. These heart rates, and the associated work loads, provided the raw data for this study. Linear regression was used to determine the PWG 170 scores, while an asymptotic regression program was chosen to predict steady-state heart rate for each subject at each work load in all four tests. These predicted steady-state heart rates were then subtracted from the last 15-second average heart rates for all work periods to yield a 'D' score. This 'D* score then gave an indication of the extent to which steady-state heart rates were achieved. The hypotheses were tested through the use of two-way and three-way ANOVA's and preplanned orthogonal comparisons. The original analysis showed a trend toward increasing PWG 170 scores with shorter duration work periods, but the effect was not significant at the .05 level. However, after a careful analysis of the results, one of the trained subjects was classified as an "outlier" (one whose data contributes too much variance to be considered representative) and another ANOVA was run with this subject's aberrant data deleted. The statistical results were now very different, with the protocols effect highly significant (p<.001), and explained well by a linear function (p<.00l). On the basis of these ambiguous findings, confident conclusions regarding the protocols effect must await further study. The first ANOVA showed no evidence of an interaction effect between state of training and the protocols effect, however the second, 'post hoc ANOVA' (with subject "outlier" deleted) found a significant difference which suggested that trained athletes may have their PWG 170 scores overestimated more than untrained subjects as a result of shorter duration protocols. There was a highly significant protocols effect in the 'D' scores (p<.00l) which was explained almost entirely by a linear function (p<.00l). This data therefore tends to support the 'post hoc ANOVA' for the PWG 170 scores, since these scores are obviously dependent on the extent to which steady-state has been achieved. Although the 'D' scores suggested that the 4-minute protocol might be optimal for achieving steady-state values, this assumes that an asymptotic first-order model accurately predicts steady-state heart rates. In this light, the lack of a significant effect of state of training or work load number/intensity on critical time, shown by this study, must be interpreted with caution. Further study with 'D' scores based on second-order models may uncover significant main and interaction effects. / Education, Faculty of / Kinesiology, School of / Graduate

The objective of the present research was to establish the biomechanical, physiological and perceptual responses of male operators to dynamic pushing tasks. The pushing tasks were performed using an industrial pallet jack with varying load/frequency combinations, in a controlled laboratory environment. Thirty healthy male subjects comprised the sample. Experimental procedures were conducted utilising the Chatillon ™ Dynamometer to measure force output in the initial, sustained and ending phases. The K4b2 Ergospirometer was used to assess physiological responses (heart rate and oxygen consumption [V02])' Nine recorded forces and nine experimental conditions formed the basis of this study, with subjects required to push three loads (200kg, 350kg, 500kg) at three frequencies (1120 sec, 1/40 sec, 1/60 sec) at a speed of 3.6km.h-1 over 14 metres on a co-efficient of friction controlled walkway for six minutes. Gait analysis, along with perceptions of exertion (,Central ' and 'Local' RPE) were collected during the third and sixth minutes of each condition . Body discomfort and contribution were identified upon completion of each condition. The results demonstrated that load and frequency interacted to influence responses within each domain. Increasing loads required increased force output during each stage of the push, which had a concomitant effect on physiological and perceptual responses. Significant differences arose between the initial, sustained and ending forces for each load, showing the direct relationship between load and force exertion. The combination of heaviest load/quickest frequency required the greatest physiological output, exceeding recommended guidelines for heart rate, V02 and energy expenditure responses. Intermediate combinations required moderate and acceptable energy cost. Linear relationships were established between heart rate and oxygen consumption , as well as between load and V02 , thus providing industrial practitioners an opportunity to evaluate task demands in situ. The combination of high forces and elevated physiological responses increased the subjective rating of the condition. The results emphasise the need to holistically consider all contributing factors in a dynamic pushing task. Dynamic pushing tasks place biomechanical, physiological and perceptual demands on the human operator, which must be minimised in order to ensure that this form of manual materials handling becomes sustainable in the long term.

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.

Call number: LD2668 .T4 1978 H35 / Master of Science

Call number: LD2668 .T4 1984 K34 / Master of Science

The objective of the present study was to investigate and compare the human responses to two load carriage tasks performed with three different load masses and on three different gradients. The task of carrying hydrogel in one hand was observed in a silviculture industry and crude physiological and perceptual responses were measured. This task was simulated in a laboratory setting together with a suggested intervention of backpack carriage. Eighteen conditions were established which consisted of the two modes of carriage and a combination of three load masses (9kg, 12kg and 15kg) and three gradients (5%, 10% and 15%). Twenty eight Rhodes University female students comprised the sample and the experimental procedures were conducted on a Quinton treadmill. Each participant was required to complete nine of the eighteen conditions which were each four minutes in duration. Postural changes were assessed using lateral and posterior digital images taken at the second and fourth minute and compression and shearing forces were estimated with the ErgolmagerTM Physiological responses (heart rate, ventilation and metabolic responses) were measured continuously with the Quark b² and perceptual responses ('central' and 'local' RPE) were measured every minute during the experimentation and body discomfort was rated at the completion of each condition. Overall responses revealed that hand carriage (146 bt.min⁻¹ , 25.09 mIO₂. kg-l.min⁻¹) was generally found to be more physiologically stressful than backpack carriage (130 bt.min⁻¹, 22.15 mIO₂.kg⁻¹ .min⁻¹) independent of load mass and gradient. Physiological responses were higher (113 bt.min-1 to 174 bt.min⁻¹ ) in responses to increasing gradient as opposed to increasing load mass (104 bt.min-1 to 153 bt.min⁻¹ ) for both backpack and hand carriage. Categorisation using the guidelines of Sanders and McCormick (1993) allowed for classification of conditions, with respect to physiological responses, into 'moderate', 'heavy' and 'very heavy' stress. For almost all of the physiological responses the majority of conditions which were classified as 'moderate' were backpack carriage conditions and the conditions classified as 'very heavy' were mostly hand carriage conditions. In terms of postural responses hand carriage resulted in more strain and greater compression and shearing forces on the spine. In terms of the compression forces increasing gradient had a greater affect on backpack carriage (681 N to 935 N) compared to hand carriage (570N to 793N). In contrast, increasing load mass had a larger affect on hand carriage postures and compression forces (751 N to 935N) in comparison to backpack carriage (723N to 780N). Shearing forces were found to be worse in hand carriage conditions overall. Although participants generally underrated perceived exertion in relation to cardiorespiratory responses, these perceptions revealed that backpack carriage, with a mean 'central' RPE of 12 compared to 11 for hand carriage, was somewhat preferred to hand carriage and that increasing gradient was perceived to be marginally more straining than increasing load mass.

The key aim of this thesis was to explore the range of emotions in the spa industry in Thailand and how emotions impact spa employees and customer service. This was achieved by identifying how emotions were performed and managed during service encounters within the spa industry. The thesis confirmed that the performance of emotion management influenced customer service delivery. To help understanding this, the thesis developed a conceptual framework based on three theoretical perspectives: Goffman’s theoretical concept, Hochschild’s acting strategy, and Bolton’s four typology of workplace emotion. Each perspective focused on different viewpoints which provided a more comprehensive and holistic view of emotion management. This research followed an interpretivist perspective to study the performance of emotion management and customer service delivery. The researcher adopted a phenomenological research strategy to understand in-depth information on emotion management. The main empirical element of the research was in-depth interviews with 48 spa employees in Chiang Mai province, Thailand. Interviews were undertaken with multiple key informants with various job roles: managers, receptionists, and therapists. Thematic analysis was used to analyze the interview data. Empirical findings indicated that emotional expressions from the spa employees influenced customer service behaviour. The spa employees performed ‘pecuniary’ emotion management category the most, followed by ‘prescriptive’ category, ‘presentational’ category and ‘philanthropic’ category. The characteristics of the spa industry in performing ‘pecuniary’ emotion management is ‘monetary servitude’, in performing ‘prescriptive’ emotion management is ‘showing a therapeutic professional face’, in ‘presentational’ emotion management is ‘Thai social reality’, and in ‘philanthropic’ emotion management is ‘emotion as a gift’.

Changes in the industrial job profile, from lifting and lowering to repetitive dynamic pushing and pulling have been facilitated through the use of manual vehicles, aimed at minimising the workload. Yet, the demands of pushing and pulling have not been well documented. Using measures of the horizontal component of the hand forces, spinal kinematics, muscle activity at various sites on the upper body and body discomfort ratings, this study aimed at quantifying the biomechanical and perceptual demands of various dynamic push/pull techniques. 36 healthy male participants performed two-handed forward pushing, two-handed backward pulling and one-handed forward pulling, employing an industrial pallet jack supporting two loads of 250kg or 500kg. While no single technique was definitively identified as preferable regarding hand forces, pushing at 500kg elicited higher initial and sustained forces (p<0.05) than one- and two-handed pulling respectively. Increments in load mass from 250kg to 500kg resulted in significant differences in the initial, sustained and ending forces. With regard to spinal kinematics in the sagittal plane, two-handed pulling elicited the highest trunk flexion, and may therefore expose individuals to prolonged forward bending. Generally this technique was found to evoke the highest sagittal responses. Spinal kinematic measures in the lateral and transverse planes suggested that one-handed pulling was accompanied by the highest measures, and hence the greatest risk of developing lower back disorders related to this plane. Although various combinations of muscles were active during each technique, one-handed pulling and pushing, most often induced the highest muscle activation levels and two-handed pulling, the lowest. While erector spinae evidenced no significant differences between techniques at each load or between loads for the same technique, activation levels were high under all conditions. Perceptual ratings of body discomfort revealed that not only is the upper body susceptible to injuries during pushing and pulling, but also that the lower extremities may have a considerable role to play in these tasks, with the calves being a particular area of concern. Findings concluded that symmetrical pushing and pulling tasks are preferable.

In order to examine the effects of prelatent/latent iron deficiency on physical work capacity and selected muscle enzyme activities, forty female subjects were studied before and after eight weeks of supplementation with either oral iron or a matching placebo. Initially, female volunteers engaged in regular endurance running were screened for iron deficiency by blood analysis (serum ferritin and hemoglobin). Forty non-anemic subjects with deficient iron stores underwent physiological and anthropometric tests to obtain a comprehensive profile. The specific physical work capacity tests were alactic and lactacid power on the Wingate cycle ergometer test, lactacid capacity on the anaerobic speed test, anaerobic (ventilatory) threshold using gas exchange variables, V0₂ max. and the max. treadmill velocity during the V0₂ max. test. Muscle biopsy samples pre-, and post- treatment were assayed for citrate synthase and alpha-glycerophosphate dehydrogenase activity. Treatment was oral iron supplementation (320 mg ferrous sulfate = 100 mg elemental iron taken as SLOW-Fe® twice a day) or a matching placebo. The subjects were randomly assigned to one of the treatment groups and a double-blind method of administration of the supplements was used. It was hypothesized that work capacity would be enhanced following oral iron supplementation, possibly due to the repletion of iron containing oxidative enzymes important in energy production. Results could not strongly support this hypothesis with the difference between the two groups on the work capacity and enzyme activity variables being statistically nonsignificant. Serum ferritin values rose from a mean of 12.4+4.5 to 37.7+19.7 ngml⁻¹ for the experimental group and 12.2±4.3 to 17.2±8.9 for the controls; (p=0.0025). Hemoglobin levels remained fairly constant for both treatment groups; 13.4±0.6 to 13.5±0.5 gdl⁻¹ (experimental), and 13.0±0.6 to 13.1+0.5 (control); (p=0.6). Pre to post values on the work capacity variables, experimental vs control respectively were: Alactic power, 8.8 to 8.4 watts-kg⁻¹ body wt. vs 8.4 to 8.2; lactacid capacity, 6.9 to 6.9 watts-kg⁻¹ body wt. vs 7.0 to 6.0; anaerobic speed test, 41.3 to 45.1 seconds vs 43.7 to 44.8; anaerobic threshold, 7.4 to 7.5 mileshour⁻¹ vs 7.2 to 7.2; V0₂ max, 51.3 to 52.7 ml-kg⁻¹ min⁻¹ vs 50.6 to 50.6; max velocity during V0₂ max, 9.8 to 9.8 mileshour⁻¹ vs 9.6 to 9.5. Except for alactic power, the change in work capacity favored the iron treated group. Noting this trend, further study may be warranted. Prelatent/latent iron deficiency appeared not to depress the activities of the two enzymes measured. Cytoplasmic alpha-glycerophosphate dehydrogenase activity rose from 0.066 to 0.085 units for the experimental group (p=.58) vs .058 to .066 for the control group and citrate synthase activity changed from 0.047 to 0.048 (experimental) vs 0.039 to 0.042 (control). It can be concluded that eight weeks of iron supplementation to prelatent/latent iron deficient, physically active females does not significantly enhance work capacity nor the activity of 2 oxidative muscle enzymes (citrate synthase and cytoplasmic alpha-glycerophosphate dehydrogenase). Within the limitations of this study the presence of a serum ferritin below 20 ng-ml⁻¹ does not pose a significant handicap to anaerobic or aerobic capacity. / Graduate and Postdoctoral Studies / Graduate

The present study examined whether and to what extent physiological rhythms of long-term . night workers become adapted to their unconventionally scheduled hours of work and sleep and how the degree of adaptation would be reflected in ratings of sleep quality, mood, anxiety, energy and satisfaction.