Thesis (PH.D.)--Michigan State University. Applied Mathematics, 2008. / Title from PDF t.p. (viewed on Aug. 11, 2009) Includes bibliographical references (p. 97-101). Also issued in print.

Dissertation (Ph.D.)--Auburn University, / Abstract. Vita. Includes bibliographic references (p.103-123).

Thesis (M.S.)--Western Washington University, 2003. / Includes bibliographical references (leaves 34-38).

Thesis (M.S.)--University of Wisconsin--La Crosse, 2002. / Includes bibliographical references.

The metabolic and biochemical adaptations which set the endurance limit in skeletal muscle and are modified by physical training, and those which set the fatigue limits in conditions of chronic hypoxia, are not completely understood. Therefore, the purpose of this study was to measure the key metabolites involved in the control of oxidative and glycolytic metabolism, during the elevated metabolic demands of exercise, in subject groups which were separated by distinct differences in their training status or by their exposure to chronic hypobaric hypoxia. Since repeated measures of the key metabolites involved in energy metabolism (PCr, Pi, ATP) and intracellular pH (pHm) would be exceedingly difficult using the conventional muscle needle biopsy technique, ³¹P NMR was selected as an appropriate, noninvasive method for measuring these metabolites. Two separate exercise models were developed for use within a 1.0 m bore NMR machine. An electrical stimulation model using the rectus femoris muscle was developed and the factors which influenced reliability and reproducibility of the data were determined. In addition, a dynamic exercise model was developed in which the gastrocnemius muscle was exercised in a mechanical calf ergometer. The results of the experiments using the electrical stimulation model indicate that RF coil geometry, stimulation intensity and duty cycle, electrode placement, and subject tolerance require very close control for the model to be reliable. It is felt that this model is best suited for experiments which require a within-subject design and is ideally suited for experimental or therapeutic intervention studies. The calf ergometer was used to compare sedentary lowlanders, marathon and ultramarathon runners, power trained athletes, and Quechua Indians, native to altitudes of 4,200 m in the Andes, before and after deacclimation to sea level. It was found that the Andean natives did not possess a standard physiological phenotype with respect to aerobic and anaerobic capacities. In addition, given the Andean's very low anaerobic capacity and intermediate aerobic capacity, this group performed calf work equivalent to that of highly trained endurance and power athletes. Moreover, pHm, PCr, Pi, and ATP showed equivalent perturbation at fatigue and in recovery compared with the marathon runners but considerably less perturbation than was found in the power trained athletes who possess equivalent aerobic capacities but far greater anaerobic capacities. NMR derivable estimates of the phosphorylation potential in this study support the theory that closer coupling between ATP supply-ATP demand may be responsible for reduced kinetic and thermodynamic activation of mitochondrial metabolism seen in the Andean natives. / Science, Faculty of / Zoology, Department of / Graduate

The purpose of the study was to determine if differences in the loading (or braking) systems of two different types of stationary bicycle ergometers (Monark and Dynavit models) influenced the performances of subjects in similar submaximal and maximal exercise. A maximal treadmill test, also performed by the subjects, was used as a criterion measure with which the maximal bicycle ergometer test results were compared. The possibility of finding differences in the performances of subjects on the two bicycle ergometers and of similarities between maximal bicycle and treadmill tests would appear to have important implications for laboratory and field testing procedures, as well as for costs of equipment used in physical fitness work and exercise physiology. Thirteen non-trained, college-aged male volunteers, 18 to 26 years, took part in the study. Each subject performed one test on each of three pieces of testing equipment; the Dynavit bicycle, the Monark bicycle, and the treadmill. Each test consisted of a maximal exercise bout of a continuous, incremental nature, during which time the appropriate physiological data was recorded. There was an interval of at least three days between tests, the subjects being assigned treatment orders via a Latin square design. Principal variables examined during maximal exercise were total work time and peak oxygen consumption; at submaximal exercise levels they were oxygen uptake and heart rate. Other variables examined, although not of central importance to the study, were maximal heart rate, maximal oxygen pulse, submaximal oxygen pulse, and subjective response to exercise. A Beckman Metabolic Measurement Cart, interfaced with a Hewlett-Packard Data Acquisition system, recorded the pertinent physiological data, which was then analyzed by the use of one and two-way ANOVA's and Newman-Keuls post hoc tests where appropriate. The results indicated no significant differences in total work time, peak oxygen consumption, maximal heart rate, maximal oxygen pulse, submaximal heart rate, submaximal oxygen uptake, submaximal oxygen pulse, and subjective response to exercise between the two bicycle ergometers. Only the treadmill elicited higher values of peak oxygen consumption than either of the cycle ergometers. This Tack of a significant difference suggests that although there may be structural differences in the loading (or braking) systems of the Dynavit and Monark ergometers, these differences are not reflected by the subjects' physiological responses to comparable levels of exercise intensity. Thus the results indicate that these bicycles could be used interchangeably for such predictive tests of physical work capacity as the Astrand-Ryhming Predicted Oxygen Uptake Test or the Modified Sjostrand PWC Test. / Education, Faculty of / Kinesiology, School of / Graduate

Anaerobic threshold speed (VTAM) was determined for 20 male university students using a continuous treadmill protocol. The onset of anaerobiosis was determined by analyzing excess CO₂ elimination. The following week, all subjects ran at the VTAM median speed of 7.25 miles per hour for 10 minutes. Recovery oxygen consumption was monitored after this run. Application of double exponential equations by computer and subsequent integration, calculated Total, Alactic, and Lactic Oxygen Debts. Subjects who ran above their VTAM (group L-VTAM) had significantly (p < .05) higher total, lactic and alactic debts than those subjects who ran below their VTAM (group H-VTAM). The total debt showed a significant (p < .05) negative correlation (r=-.77) to in; group L-VTAM. This appears to be due to the increasing lactic debt, that was also significantly (p < .05) negatively correlated (r=-.73) to VTAM. Group H-VTAM did not exhibit this characteristic. This study demonstrates that VTAM is a critical factor in determining oxygen debt and therefore, work above this point results in the onset of metabolic acidosis, which may limit the optimal running speed for a given distance. / Education, Faculty of / Kinesiology, School of / Graduate

The physiological limit to maximum aerobic capacity (VO2max) in vertebrates has been attributed to cardiovascular oxygen delivery, to the ability of the muscle cells to consume oxygen, or to a fine-tuned development of all components of the respiratory system such that no single component can be shown to limit VO2max. The above hypotheses have each been developed using different experiments with different animals. The comparative studies uniting these animals and methods are limited. In order to further our knowledge of the cellular limit to VO2max, skeletal muscle mitochondria were isolated from species representing four vertebrate classes, and endothermic and ectothermic physiology. Mitochondrial VO2 was measured at 15, 25 and 35°C and the results were compared between species and endothermic and ectothermic groups. Mitochondrial enzyme activities were measured at the three treatment temperatures to ascertain which enzyme activity best represents VO2max for all vertebrates. Cytochrome difference spectra were measured to determine the concentrations of mitochondrial cytochromes c+c1 . The results show that mitochondria are unique in all species tested. Each species has its own response to changing temperature and its own mitochondrial enzyme activity profile. In addition, in vitro measurements of mitochondrial VO2 for all species show rates significantly higher than those estimated from whole organism measurements of VO2max, suggesting that mitochondrial oxygen uptake is not a factor limiting organismal V02max. The Q10 for mitochondrial VO2 differed significantly between groups, indicating that differences in VO2max between endotherms and ectotherms cannot be explained solely on the basis of temperature. The activation energy (Ea) of mitochondrial VO2 was significantly higher in endotherms compared to ectotherms. Mitochondrial enzyme activities did not show the same Q10 and Ea differences as the intact mitochondria. Since enzyme activities were measured on mitochondria disrupted with either detergent or sonication, physical properties of the mitochondrial inner membrane are suggested as being responsible for these differences.

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