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dc.contributor.advisorCoyle, Edward F., 1952-en
dc.creatorTrinity, Joel Douglasen
dc.date.accessioned2010-06-03T16:07:31Zen
dc.date.available2010-06-03T16:07:31Zen
dc.date.issued2009-12en
dc.identifier.urihttp://hdl.handle.net/2152/7667en
dc.descriptiontexten
dc.description.abstractThese studies investigated the impact of intensity and body temperature on performance and cardiovascular regulation during high intensity and prolonged exercise. In study 1, polyphenol antioxidant supplementation proved to have no effect on exercise performance and related variables (gross efficiency, perceived exertion, maximal power) during exercise in the heat. Furthermore, there were no differences between the cardiovascular or thermoregulatory responses between control and antioxidant treatments. Study 2 utilized an integrative approach to investigate a classic topic in exercise physiology, namely, is the cardiac output to oxygen consumption relationship linear across a wide range of exercise intensities? The slope of the CO vs. VO2 relationship was significantly reduced from 70 to 100% of VO2max when compared to the slope from 40 to 70% of VO2max (2.0 ± 0.4 vs. 4.4 ± 0.3 l/min, p = 0.025). This finding, in combination with the plateau and eventual reduction in stroke volume at high intensity exercise compared to moderate intensity exercise (146.0 ± 16.6 vs. 138.5 ± 14.9 ml/beat, p = 0.015), argues in favor of a cardiac limitation to high intensity exercise. This study also showed that the pattern of oxygen extraction at the whole body level (arterial venous O2 difference) and the muscle level (deoxygenated hemoglobin) is not similar and that muscle specific differences exist regarding oxygen extraction. Study 3 determined that hyperthermia (elevation of skin temperature by 4.3°C and core temperature by 0.8°C) did not reduce SV independent of the increase in HR. Even under conditions of moderate hyperthermia the reduction in SV is due to the increase in HR and temporally unrelated to increases in cutaneous blood flow. In summary, antioxidant supplementation had no effect on performance, cardiovascular, or thermoregulatory responses to exercise in the heat in well trained subjects. High intensity exercise is associated with a reduced rate of increase in the CO vs. VO2 relationship. Finally, hyperthermia does not reduce SV during exercise when HR is maintained at normal levels.en
dc.format.mediumelectronicen
dc.language.isoengen
dc.rightsCopyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works.en
dc.subjectExercise and cardiovascular responseen
dc.subjectCardiovascular responseen
dc.subjectExercise intensityen
dc.subjectBody temperatureen
dc.subjectExercise performanceen
dc.subjectThermoregulatory responseen
dc.subjectAntioxidant supplementsen
dc.subjectHyperthermiaen
dc.titleImpact of intensity and body temperature on cardiovascular responses to exerciseen
dc.description.departmentKinesiology and Health Educationen
thesis.degree.departmentKinesiology and Health Educationen
thesis.degree.disciplineKinesiologyen
thesis.degree.grantorThe University of Texas at Austinen
thesis.degree.levelDoctoralen
thesis.degree.nameDoctor of Philosophyen


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