1 v. (various paging) : ill. ; 26 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.1976) from the Dept. of Human Physiology and Pharmacology, University of Adelaide

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.

The objective of the present study was to establish effective combinations of marching speed and backpack load in order to meet specific military requirements. Thirty infantrymen from the South African National Defence Force (SANDF) comprised the sample and experimental procedures were conducted in a laboratory setting using a Cybex Trotter treadmill. Sixteen conditions were set up which included combinations of four speeds (3.5, 4.5, 5.5, and 6.5 km.h⁻¹) and four backpack loads (20, 35, 50, and 65kg). Each subject was required to complete 8 of the sixteen conditions, each consisting of a six-minute treadmill march. Physiological data (heart rate, ventilation and metabolic responses), kinematic gait responses (step-rate and stride length) and perceptions of exertion (“Central” and “Local” RPE) were collected during the third and sixth minutes of the treadmill march and areas of body discomfort were identified post-march. Responses revealed five distinct categories of exertional strain. Three marches constituted “nominal” (below 40% VO₂max) and three “excessive” strain (above 75% VO₂ max). These represent combinations of extreme military demands and are highly unlikely to be utilised by the military. Three “tolerable” levels of required effort were recommended and these 10 combinations were further divided into three sub-categories. The “moderate” stress marches were identified as “ideal” for prolonged marches and had statistically similar responses of working heart rates (range of 118 bt.min⁻¹ to 127 bt.min⁻¹), energy expenditure (26 kJ.min⁻¹ and 27 kJ.min⁻¹) and ratings of perceived exertion (“Central” ratings of 10 and 11). Thus, marching at 5.5 km.h⁻¹with 20kg, 4.5 km.h⁻¹ with 35kg or 3.5 km.h⁻¹ with 50kg all require a similar energy cost. Four “heavy” category marches were identified for possible use when the duration of the march is reduced. During these marches responses were statistically similar with heart rates ranging from 127 bt.min⁻¹ to 137 bt.min⁻¹, energy expenditure from 32 kJ.min⁻¹ to 37 kJ.min⁻¹ and “Central” ratings of perceived exertion were 12 and 13. When short, high intensity marches are necessary, then combinations from the “very heavy” category may be utilised but with caution. During these marches, soldiers were taxed between 65% and 75% of VO2 max. The results of this study clearly demonstrate that the interplay between speed and load needs to be adjusted when determining “ideal” combinations for specific military demands. Essentially, if speed is of the essence then load must be reduced, and if heavy loads need to be transported then speed must be reduced.

[Conclusions] l) The two forms of human locomotion, walking and running, are distinctly different and in evaluating these gait patterns consideration must be given to this fact. 2) The impression created by the energy cost curves, that there is a single locomotor interface for both walking and running is a false one . There are two distinctly different locomotor interfaces, the walk-to-run interface and the run-to-walk interface. The former appears to correspond with the "metabolic intersection point" and therefore has some metabolic significance. The latter appears to be merely an "overshoot" of the walk-to-run interface and presently has no apparent metabolic significance. 3) Because the walk-to-run interface speed corresponds with the intersection point of the energy cost curves, physiological responses to walking and running at this speed do not differ significantly. However, cadence and stride length patterns for these two locomotor patterns are distinctly different at this point. 4) The identification of single physiological or kinematic factors during perceptions of exertion in any given situation is an extremely difficult if not impossible task. Perceived exertion should therefore be considered a multi-factorial concept and should be evaluated as such. 5) The use of relative speed as a technique for reducing inter-subject variability in physiological and kinematic factors is worthless unless diverse ranges in morphological linearity are a characteristic of one's subject pool

The purpose of this study was to examine differences in 2,3-diphospho-glycerate concentrations among groups of smokers and nonsmokers, to determine relationships between 2,3-DPG concentrations and other blood parameters affecting oxygen transport, and to examine the effects of acute exercise on 2,3-DPG concentrations. Antecubital venous blood from each subject, before and after exercise, was analyzed for 2,3-DPG, hematocrit, hemoglobin and blood pH. Mean corpuscular hemoglobin concentration (MCHC) was calculated by dividing hemoglobin by hematocrit. Forty university-aged males constituted the sample population. Each subject was assigned to one of five groups, eight subjects per group, based on his status in relation to the variables of physical activity and cigarette smoking. The task consisted of one hour of exercise on a bicycle ergometer at a work rate producing a heartrate of approximately 150 beats per minute (70 per cent of maximal aerobic capacity). Blood samples were taken immediately prior to and immediately following the bout of exercise. A 12 hour fast preceded the work phase of the experiment. The hypotheses were: highly fit subjects have significantly higher 2,3-DPG concentrations and sedentary subjects have significantly lower 2,3-DPG concentrations than moderately fit subjects; smokers have significantly higher 2,3-DPG levels than nonsmokers; exercise produces significant increases in 2,3-DPG; negative relationships exist between 2,3-DPG levels and hemoglobin levels as well as between pre exercise 2,3-DPG levels and change of 2,3-DPG as a result of exercise. A priori orthogonal comparisons of pre exercise red cell 2,3-DPG levels indicated that differences between groups were not significant, i.e. highly fit groups did not demonstrate 2,3-DPG levels significantly higher, nor did sedentary groups demonstrate 2,3-DPG levels significantly lower than moderately fit groups. A definite trend towards higher 2,3-DPG levels was observed as training intensity increased, indicating that the hypothesis of physical training producing an increase in 2,3-DPG levels should not be totally rejected. Demonstration of differences in the carrying capacity of the blood, as reflected by differences in MCHC, hemoglobin and hematocrit, between groups appeared to be related to the trend observed in 2,3-DPG levels. Differences between smokers and nonsmokers in relation to 2,3-DPG concentrations were not significant,indicating that the hypoxia produced through cigarette smoking is not an important stimulator of 2,3-DPG production. Multivariate analysis of results indicated that 2,3-DPG levels were not significantly increased as a result of one hour of exercise at 70 per cent of maximal aerobic capacity. This is indicative of a slow-acting response mechanism affecting 2,3-DPG production, which requires more than one hour, or a more severe stress, to produce a physiological beneficial effect on oxygen transport by the blood. A significant negative correlation was observed between pre exercise levels of 2,3-DPG and hemoglobin levels. This was also reflected in the significant negative correlation between 2,3-DPG and hematocrit and 2,3-DPG and MCHC. A negative correlation was also observed between the change in 2,3-DPG and the change of MCHC that occurred as a result of exercise. The results are interpreted as showing a compensatory effect of 2,3-DPG in producing increased unloading of oxygen when the carrying capacity of the blood is reduced through a reduction in hemoglobin levels. An intimate relationship between 2,3-DPG and MCHC, tending to produce homeostasis in the position of the oxygen dissociation curve of hemoglobin, has been postulated. Changes in 2,3-DPG as a result of exercise were not related to the pre exercise concentration of 2,3-DPG indicating that change of 2,3-DPG is not significantly affected by the amount of 2,3-DPG present before physical activity is initiated. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate

Nine male Physical Education students were selected to test the hypothesis that addition of CO₂ to the inspired air during recovery will cause significant increases in ventilation above control conditions and that recovery from submaximal exercise will be enhanced by the addition of 2.78% or 5.80% CO₂ to room air. The exercise was administered for six minutes at a workload predetermined to elicit 75% of his maximal oxygen uptake. The dependent variables (heart rate, ventilation, oxygen uptake, and carbon dioxide elimination) were subjected to a one way analysis of variance and significant F ratios evaluated using Dunnett's Test. Ventilation is increased significantly (p<.05) above control values with the addition of 5.80% CO₂ to room air during recovery however, there is no significant increase in oxygen uptake. The addition of 2.78% CO₂ to room air during recovery does not significantly (p>.05) increase ventilation; there is however a significant (p<.05) increase in oxygen uptake in the first 30 seconds of recovery. Neither treatment effect causes significant changes in heart rate. The addition of 5.80% CO₂ to the inspired air significantly (p<.05) reduces carbon dioxide elimination. In 4 subjects, the effect produced a carbon dioxide uptake at certain time intervals. The addition of 2.78% CO₂ to the inspired air caused a significant (p<.05) reduction of carbon dioxide elimination in the first minute of recovery. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate

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