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.

Please read the abstract (Synopsis) in the section 00front of this document / Dissertation (MA (Human Movement Sciences))--University of Pretoria, 2007. / Biokinetics, Sport and Leisure Sciences / MA / unrestricted

Photocopy of typescript.

Whole Body Vibration (WBV) training is a new addition to the field of Exercise and Sports Science and has been developed for the use in strength and conditioning exercises. With the introduction of this new mode of exercise, the study focused on comparing the strength gaining effect of WBV training versus conventional resistance training. The study was conducted in a descriptive, exploratory manner utilizing a quasi-experimental approach with a three group comparison pre-test-post-test design consisting of an experimental-, comparison- and control group. Convenience and snowball sampling were used to select 43 male and female healthy, sedentary volunteer participants. The research focused on reviewing the contribution that each mode of training offers to increase strength in the upper leg and underlines the important physiological adaptations that the human body undergoes to bring about an increase in muscle strength. Both the whole body vibration and land-based resistance groups trained three times a week over an eight week intervention period. Exercises were performed with progressive increments in the frequency, amplitude and duration for the WBV- and in workload, number of sets and repetitions for the conventional resistance training program. The control group remained sedentary throughout the duration of the study. The dependent variables of peak torque flexion and extension of the knee joint in both legs were analyzed using descriptive and inferential statistics. Analysis of covariance (ANCOVA) was done to determine intra-group differences. Post-hoc analysis in the form of Scheffé’s test was done to determine and compare inter-group differences. Practical significance was indicated by means of Partial eta2 The analysis of the results revealed significant strength increases in both conventional resistance training and WBV for most of the dependent variables, except for peak torque extension, where the WBV group did not increase significantly. Based on these results, it can be concluded that both modes of conventional resistance and whole body vibration increased selected dependent variables for upper leg strength in previously inactive individuals.

To investigate the relationship between pulmonary diffusion limitation, ventilation-perfusion (VA/Q) mismatch, pulmonary transit times (PTT) and pulmonary gas exchange during exercise, 10 highly trained male athletes (age=26.4±4.4 years, Height=185.5±5.3cms, Weight=78.2±8.6 kg, V 02max=5.15±0.521-min-1) under went exercise testing at rest (R) and 150W, 300W and maximal exercise (372±22W), corresponding to an oxygen consumption (V0₂) of 0.41±0.09, 2.16±0.17, 4.32±0.35 and 5.13±0.50 1-min-1respectively, while trace amounts of six inert gases were infused via a peripheral vein. Arterial blood samples, mixed expired gas samples and metabolic data were obtained. Observed alveolar arterial difference ([A-a]D0₂(0)was calculated according to the alveolar gas equation. Indices of VA/Q mismatch: LogSDi and Log SDa and predicted [A-a]D0₂([A-a]DO₂(p)) were derived from 50 compartment model analysis of retentions and excretions of the inert gases. Additional indices of '/A/I,) mismatch: DISPR*, DISPE and DISPR*_E and inert gas alveolar difference ([A-a]D, R(A-a)D and E(A-a)D) were obtained directly from the inert gas data. One to two weeks later, the subjects underwent first pass radionuclide angiography using a Siemens ZLC wide field of view gamma camera. Following in vitro labeling with 99mTechnecium, 5-10 ml of the subject's blood, containing 10-20 mCi of activity, were injected at rest. First pass and post-static data were obtained on an ADAC 3003 computer and cardiac output was calculated using the Stewart Hamilton equation. PTT was determined using deconvolution and centroid methods. Gated radionuclide angiography was then performed at rest, 150, and 300W. On a separate occasion, first pass cardiac outputs and pulmonary transit times were obtained at maximal exercise. Mean arterial partial pressure of 0₂ (Pa0₂) decreased significantly from rest to 150W , and from 150 to 300W to a low value of 86±9 torn, before increasing to near resting values at maximal exercise. [A-a]D0₂(3) increased across each exercise levels however only the increase from 150 to 300 W was significant. The overall and perfusion-related indices of VA/Q mismatch showed a significant increase with exercise, mainly as a result of increasing perfusion of areas of high VA/Q [A-a]D0₂(0 was greater than predicted, becoming significant during heavy exercise, indicating diffusion limitation. Cardiac output increased from 6.9±0.9 1-min-1 (R) to 25.2±2.5 1-min-1 at 300W and 33.3±3.7 1-min-1 at maximal exercise. End diastolic volume increased from R to heavy exercise (p < 0.001), accompanied by a decrease in end systolic volume (p =0.05). Stroke volume and ejection fraction also increased significantly from R to 300W (p <0.001). Deconvolution PTT decreased from 9.32±1.41 s at rest to 2.91±0.30 s during max exercise and was highly correlated with centroid PTT both at rest (r=0.99, p<0.001) and during maximal exercise (r=0.96, p<0.001). PTT during maximal exercise was significantly correlated with Pa0₂ (1=0.65, p<0.05) and [A-a]D0₂(0)_[A-a]D0₂(p) (r=-0.60, p<0.05). Calculated pulmonary blood volume increased during maximal exercise by 57% over resting values to over 25% of total blood volume and when corrected for body surface area correlated significantly with Pa0₂ (r=0.69, p<0.05). There was a significant correlation between (A-a)D, PTT, the ventilatory equivalent for CO₂ and Pa0₂ during maximal exercise (r=0.94, p<0.01) allowing prediction of over 80% of the variance in Pa0₂ between subjects. These data indicate that highly trained athletes develop VA/Q mismatch accompanied by diffusion limitation during maximal exercise. Observed decrease in Pa0₂2 during high intensity exercise is the result of a complex interaction between VA/Q mismatch, hypoventilation and diffusion limitation secondary to shortened pulmonary transit. / Graduate and Postdoctoral Studies / Graduate

The enzymatic organization of muscle tissue usually is examined in only a select few muscles of any one animal species. However, because the functional demands placed on individual muscles can vary so widely from muscle to muscle, it is inappropriate to generalize findings from one or two muscles to muscle tissue in general. The differences or similarities in metabolic machinery between skeletal muscles of a wide functional range provides crucial information with respect to a particular animals' whole body metabolism. Nowhere is this understanding more important than in the diving marine mammal which must operate as a closed system (with respect to oxygen supply) while submerged. The goals of this thesis are: 1) to provide a broad body of information on the metabolic organization of a large cross-section of marine mammal muscles, both functionally and with regard to location, 2) to assess the implications of the enzyme differences between muscles to the diving habit, and 3) to compare the metabolic organization of skeletal muscle among several species of marine mammal with different diving abilities and habits. A series of 13 enzymes were measured in 21 skeletal muscles of the harbor seal, Phoca vitulina. In addition, 23 enzyme activity ratios were calculated and analyzed for these muscles. A similar analysis of 22 muscles from fin whales, Balaenoptera physalis. was conducted --including 7 key enzymes and 15 activity ratios. Overall, both the maximum activities and the enzyme activity ratios are consistent with the idea that marine mammal muscle is typical mammalian muscle, exhibiting few significant differences from terrestrial species with respect to catabolic enzymes. The only obvious exception to this in the species examined is observed with fin whale locomotory muscle which has extremely high activities of lactate dehydrogenase (over 2000 units/gm wet wt at 25°C) due to an apparent scaling phenomenon. Tight control of this high potential glycolytic flux is indicated by pyruvate kinase activities that scale downward. Comparisons of enzyme relationships between muscles of harbor seals seem to indicate a very aerobically poised metabolic make-up. This is especially true with respiratory and locomotory muscles, which also show a high tendency to utilize fat. This pattern of enzyme activities and activity ratios in the locomotory muscles of harbor seal is evidence that muscle contractile activity while diving is powered primarily through oxidative pathways and largely based on fat as fuel. The majority of non-locomotory muscles appear to be more able to function anaerobically utilizing carbohydrate. This pattern may correlate with circulatory redistributions while diving that preferentially fuel the locomotory muscles with oxygen, leaving the inactive muscles significantly more hypoperfused and, therefore, candidates for energy saving O₂ sparing (metabolic depression). Fin whales exhibit an opposite pattern, with enzyme profiles more typical of "white" muscle. Unlike harbor seals, the locomotory muscles of fin whales are consistently the least oxidatively poised of the muscles examined. This apparently more anaerobic nature of fin whale muscle is possibly complicated by scaling adaptations, but appears to be a real phenomenon. The examination of three to four skeletal muscles from each of three additional phocid seal species from Antarctica, leopard seals (Hydrurga leptonyx). crab-eater seals (Lobodon carcinophagus). and Weddell seals (Leptonychotes weddelli) confirm that the harbor seal pattern of enzyme profiles is fairly consistent among phocid seals. By these criteria skeletal muscles of phocid seals (particularly the locomotory and respiratory muscles) appear to be designed for sustained aerobic metabolism during diving regardless of the habits or diving capabilities of the seal. / Science, Faculty of / Zoology, Department of / Graduate

The purpose of this study was to investigate the effects of special training in motor ability skills on the reading ability of grade two pupils who have a specific reading disability. Thirty subjects, all of them grade two pupils at the Sir Richard McBride Elementary School in Vancouver, British Columbia, were selected. All were classed as poor readers on the basis of the Metropolitan Reading Achievement Test. The subjects were given pre-trainlng standardized tests in Mental Ability, Reading Achievement, Visual Perception, and General Motor Capacity. They were then randomly assigned to five sub-groups for Special Training purposes. Group I was the control group. Group II received extra instruction in motor skills and reading. Group III were given special training in motor skills. Group IV received extra reading instruction, and Group V received special training in both reading and visual perception. The thirty subjects were equally distributed, six in each group. The experimental groups received approximately fifty minutes of special training every day for a period of sixty-five days. Case Studies were made of the six subjects in Group III, the Motor Ability Group. At the conclusion of the Special Training Period, all subjects were again tested in general motor capacity, visual perception, and reading ability. Initial and final test scores in motor capacity, perception, and reading were analysed by Fisher's t statistic and the differences between mean improvements of the five groups were discussed. Case Study Reports were written for each of the subjects in Group III. A review of the Case Study Reports revealed that all of the subjects in the Motor Ability Group improved in reading ability, visual perception, and motor skills. The group mean scores, before and after training, indicated that children who received special training in motor skills (Group III) improved in reading ability as measured by the Metropolitan Reading Achievement Test, but no more than children in any of the remaining groups. It appears also that special training in motor ability skills can cause an improvement in the motor ability and visual perception of children at this age level. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate

The extreme elevation in plasma levels of norepinephrine (NE) and epinephrine (EP) which occurs during forced diving of ducks (Anas platyrhynchos) was studied before and after denervation of the adrenal glands. Elevated PaCO₂, decreased arterial pH, decreased blood glucose as well as low PaO₂ have been described as causal factors in this response. These variables, as well as blood pressure, heart rate and breathing frequency were measured in ducks dived after breathing air or pure 0₂ to clarify and quantify the mechanism involved and its physiological function. Both NE and EP concentration increased by up to 2 orders of magnitude in the 4 minute dive period, but by a significantly lesser amount if the duck breathed 0₂, before the dive. While pH and PaCO₂ were well correlated with the changes in plasma NE and EP levels during both air and 0₂ dives, both pH and PaCO₂ changed more in the 0₂ trials, indicating that they are not the primary cause of the response. Plasma glucose levels were variable. PaO₂ values less than normal correlated well with increasing NE and EP concentrations, but at high PaO₂s, there was no correlation, suggesting that hypoxia is the permissive state for the full response. Compared with breathing air, breathing O₂ before the dive attenuated the diving bradycardia, eliminated the decrease in blood pressure normally observed during dives, and caused more extreme changes in pH, PaC0₂, and of course, PaO₂. Denervating the adrenals decreased the amounts of both catecholamines released during dives after breathing air and 0₂, EP significantly more than NE. Adrenal denervation per se did not cause a significant change in heart rate, blood pressure, arterial gas tensions, pH, or plasma glucose changes during dives although the operation caused increased variation in some of the parameters. In ducks, the cause for the catecholamine release is decreasing PaO₂ and full expression of the response is dependent on intact innervation of the adrenal gland, although there is a component that is unaffected by denervation. While possible roles for this response are discussed, the true physiological function of this response remains cast in shadows. / Science, Faculty of / Zoology, Department of / Graduate

Cardiovascular responses evoked during forced submersion enable the Pekin duck (Anas platyrhynchos) to survive protracted periods of asphyxia. The responses include an extraordinary bradycardia and intense peripheral vasoconstriction with the result that blood flow is favoured to those organs most susceptible to lack of oxygen. These adjustments appear to be mediated via the caudal brainstem following stimulation of peripheral and central arterial chemoreceptors. The minor role that baroreceptors play in the generation of these responses was demonstrated by the persistence of the cardiovascular changes following peripheral arterial baroreceptor denervation. Isolation of the cephalic circulation from the systemic circulation enabled a series of experiments to assess the relative contributions from peripheral chemoreceptors, located in the carotid bodies, and from unidentified central chemoreceptors within the cranial circulation. A declining arterial P0₂ in the systemic circulation appeared especially potent in evoking bradycardia during submersion. Increased arterial PC0₂, likewise, resulted in a reduced heart rate. Similar changes in the blood gas levels of the cephalic circulation did not elicit significant bradycardia. However, both receptor groups responded to arterial hypoxic hypercapnia by activating substantial reduction in peripheral blood flow, as reflected by the rise in hind limb vascular resistance. Although baroreceptors may continue to mitigate changes in arterial blood pressure and cause some change in heart rate and vascular resistance, chemoreceptors appear to be predominantly responsible for the changes during submersion. The cardiac response to chemoreceptor stimulation during submersion was discovered to habituate following repetitive diving. Habituation was so pronounced in some ducks that after several training sessions the bradycardia during 40-second forced dives was abolished. Habituation of the cardiac response appeared dependent on the intensity of chemoreceptor stimulation. With severe arterial hypoxia, produced by either prolonging dive times or by reducing the pre-dive inspired oxygen content, little or no cardiac habituation was observed. Tests were conducted to demonstrate efficacy of the cardioinhibitory efferent discharge. Maintained sensitivity of chemoreceptors was suggested by the lack of change in oxygen breathing tests before and after training. Furthermore, the persistence of stimulus intensity was established and these observations led to the suggestion that the locus of habituation is within the CNS. The demonstration that the level of bradycardia was dependent on arterial P0₂ in both naive and habituated animals argues against the contention that the diving response is a fear response. Further evidence against this view was provided by the demonstration that the diving response remains essentially intact following transection in the rostral mesencephalon below the level of the hypothalamus. It is concluded that chemoreceptor-driven cardiovascular changes evoked as part of the diving response are mediated by regions of the CNS below the rostral brainstem. Modification of these responses can be produced in the intact animal by simple forms of learning. However, it remains uncertain at what level this influence arises. / Science, Faculty of / Zoology, Department of / Graduate

During pregnancy, body fat stores increase in part to subsidize the high energy cost of lactation. One effect of exercise, on the other hand, is to lower percent body fat. The effect of exercise during pregnancy and lactation on body fat, and on body composition in general, is not well documented. There is also a paucity of data on the effect of exercise during these physiological states on food intake and body weight. If exercise during pregnancy decreases body fat stores, would lactation performance subsequently be compromised? This study was designed to determine the effect of moderately strenuous aerobic exercise, during rat pregnancy and lactation, on food intake, body weight, body composition and lactation performance. Virgin female Sprague-Dawley rats were divided into exercised (n=40) and sedentary (n=40) groups. Exercising rats were trained over three weeks to run on a treadmill at 30 m/min, 2 hours/day, 5 days/week. Within each group, two subgroups were then mated and three subgroups remained as virgin age controls (n=8 per subgroup). Of the mated subgroups, one was terminated within 24 hours of parturition and the other on day 14 of lactation. Subgroups of virgin sedentary and exercising controls were terminated at times corresponding to each of mating, parturition and day 14 of lactation of mated animals. Carcasses were assayed for fat, water, ash and protein. Ad libitum food intake and body weight were monitored throughout the study, as was the weight gain of pups of lactating dams. MANOVA showed the effect of activity to be significant on food intake at week three of training and during the pregnancy period (p<0.00l) and at week one (p<0.0l) and two (p<0.05) of lactation. The effect of activity was highly significant (p<0.00l) on body weight from week three of training and throughout the pregnancy and lactation periods, as well as on the percent fat, water and ash of the rat carcasses. Post hoc multimean comparisons (Scheffe) at the p<0.05 level revealed that exercise resulted in a significant increase in the food intake of virgin rats, and nonsignificant increases in the food intake of pregnant and lactating rats. Body weights of virgin, pregnant and lactating exercising rats were significantly greater than their respective sedentary controls. Despite their heavier body weights and greater food intake, the estimated carcass energy content of exercising animals was lower than that of sedentary animals. This finding was reflected in the carcass composition whereby exercising rats, whether virgin, pregnant or lactating, contained consistently less fat and more water than sedentary controls. At parturition, pregnant animals contained significantly less fat, more water and more ash than sedentary pregnant controls. After 14 days of lactation, there were no significant differences in carcass composition between exercising and sedentary dams. However, lactating rats, whether exercising or sedentary, catabolized approximately 50 percent of the body fat present at parturition. Pup weight gains were not significantly different between exercising and sedentary dams. From these findings it was concluded that the effect of exercise during pregnancy and lactation on food intake, body weight and body composition was comparable to its effect in non-gravid rats. Moderately strenuous exercise during pregnancy prevented the increase in body fat deposition normally present at this time. Despite these depleted fat stores, the energy supplied by the mobilization of the remaining fat and the increase in food intake was adequate to support normal pup growth. / Land and Food Systems, Faculty of / Graduate