Thesis (M.S.)--University of Wisconsin--Madison, 1966. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Texas at El Paso, 2008. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (M.S.)--University of British Columbia, 2003. / Includes bibliographical references (leaves 36-44). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.

Thesis (Ph. D.)--University of Cape Town, 2003. / Includes bibliographical references (leaves 284-287). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.

Thesis (M.Phys.Ed.)--Memorial University of Newfoundland, 2002. / Bibliography: leaves 66-76.

Thesis (M.S.)--University of British Columbia, 2003. / Includes bibliographical references (leaves 36-44).

Thesis (Ph. D.)--University of Cape Town, 2003. / Includes bibliographical references (leaves 284-287).

Fatigue is defined as an exercise-induced decrease in maximal voluntary force produced by a muscle. Fatigue may arise from central and/or peripheral mechanisms. Supraspinal fatigue (a component of central fatigue) is defined as a suboptimal output from the motor cortex and measured using transcranial magnetic stimulation (TMS). Reductions in O2 supply (hypoxia) exacerbate fatigue and as the severity of hypoxia increases, central mechanisms of fatigue are thought to contribute more to exercise intolerance. In study 1, the feasibility of TMS to measure cortical voluntary activation and supraspinal fatigue of human knee-extensors was determined. TMS produced reliable measurements of cortical voluntary activation within- and between-days, and enabled the assessment of supraspinal fatigue. In study 2, the mechanisms of fatigue during single-limb exercise in normoxia (arterial O2 saturation [SaO2] ~98%), and mild to severe hypoxia (SaO2 93-80%) were determined. Hypoxia did not alter neuromuscular function or cortical voluntary activation of the knee-extensors at rest, despite large reductions in cerebral oxygenation. Maximal force declined by ~30% after single-limb exercise in all conditions, despite reduced exercise time in severe-hypoxia compared to normoxia (15.9 ± 5.4 vs. 24.7 ± 5.5 min; p < 0.05). Peripheral mechanisms of fatigue contributed more to the reduction in force generating capacity of the knee-extensors following single-limb exercise in normoxia and mild- to moderate-hypoxia, whereas supraspinal fatigue played a greater role in severe-hypoxia. In study 3, the effect of constant-load cycling exercise to the limit of tolerance in hypoxia (SaO2 ~80%) and normoxia was investigated. Time to the limit of tolerance was significantly shorter in hypoxia compared to normoxia (3.6 ± 1.3 vs. 8.1 ± 2.9 min; p < 0.001). The reductions in maximal voluntary force and knee-extensor twitch force at task-failure were not different in hypoxia compared to normoxia. However, the level of supraspinal fatigue was exacerbated in hypoxia, and occurred in parallel with reductions in cerebral oxygenation and O2 delivery. Supraspinal fatigue contributes to the decrease in whole-body exercise tolerance in hypoxia, presumably as a consequence of inadequate O2 delivery to the brain.

The purpose of this study was to determine if fitness levels of individuals affect cognitive function. This study seeks to show how response inhibition and accuracy are affected following a mentally fatiguing task. Response inhibition refers to the suppression of actions that are inappropriate and that interfere with goal driven behavior. Response inhibition in reference to the continuous performance task (CPT) is measured in false clicks. The tasks for the CPT were completed after either a controlled period of rest or moderate-intensity exercise. Subjects were either Georgia Tech Division I track athletes or students leading a sedentary lifestyle. All subjects participated in two test protocols. Athletic subjects completed the resting protocol first, while sedentary subjects completed the exercise protocol first. Subjects reported to the lab following an overnight fast. They completed an initial set of paper work and signed a consent form, filled out a 24 hour history form and completed a Profile of Moods States (POMS) and Visual Analog Scale (VAS) form. Subjects then took a 20-minute (CPT). The CPT is a neuropsychological test that measures an individual’s sustained and selective attention. The length of the test is 20 minutes in order to induce mental fatigue. The goal of the test is to click in a white box when the letter T is seen. Immediately after subjects filled out a secondary set of paperwork. Once paper work was complete subjects either rested or exercised for 35 minutes. If subject was classified as an athlete, trial 1 was rest, while trial 2 was exercise. If subject was classified as a sedentary student, trial 1 was exercise, and trial 2 was rest. After the subject completed either the cycling or resting portion they repeated the CPT for five minutes. It was hypothesized that that the effects of moderate exercise positively affect the subject’s performance on the CPT. I expect false clicks following the 5 minute CPT to be lower after exercising. I hypothesize that for both groups their accuracy should be higher after moderate cycling and that higher fitness level should decrease the level of mental fatigue experienced throughout the CPT.