This study examined the effects of rapid and uncompensable core temperature (Tc) acquisition on cerebral oxygenation and haemodynamics, cerebral neural function, decision-making, and rate and magnitude salivary cortisol appearance. Fourteen male subjects (mean age, 33.6 ± 12.1 years) performed an incremental treadmill exercise test to a termination criterion in a control session (CON) and an experimental session (PPE). The incremental treadmill exercise test protocol included an initial 5-minute stage at 3.5 mph and a 0% grade, the second stage was 5-minutes at 3.5 mph at 4% grade, the third stage was 50-minutes at 3.5 mph and an 8% grade, and the final stage was 1-hour at 3.5 mph and a 12% grade. The Instrumentation included a near-infrared spectroscopy (NIRS) monitor, MUSE EEG monitoring system, Equivital integrated physiological monitoring system, Tc capsules, and salivary cortisol oral swabs and ELISA kit for salivary analysis. Important physiological results were significant differences in the physiological strain index (PSI) at all common points of measurement. Important cerebral oxygenation and haemodynamics results were a plateau in left-side prefrontal cortex (PFC) HbO2 and tHb at roughly Tc 38°C in both CON and PPE, 80% of TTT in CON, and 60% of TTT in PPE. Additionally, there was higher left-side PFC activation during PPE as indicated by a significant decrease in TSI % from start to end of exercise and double the decrease in TSI % per minute in PPE when compared to CON. There were no significant differences during the CON session. An analysis of frontal theta EEG power results showed a significant decrease when comparing pre- and post-exercise values during a Go/No-go test in PPE (F(1,13) = 6.069, p ≤ 0.05)). There was also a significant difference when evaluating incorrect responses between pre- and post-exercise values in PPE (F(1,13) = 12.785, p ≤ 0.01)); these differences were not observed during CON. There was also a difference in the rate of cortisol appearance (CON = 0.002 µg dL-1 min-1; PPE = 0.018 µg dL-1 min-1). In the PPE condition, mean cortisol values between start of exercise and the measurement point associated with Tc 38°C and between the start and end of exercise during PPE were significantly different (F(1,13) = 22.71, p ≤ 0.01). Lastly, there was a significant difference between magnitude of cortisol values at the termination between CON and PPE. These data suggest that rapid and uncompensable Tc acquisition during PPE caused an altered cerebral oxygenation and haemodynamic response in the left-side PFC when compared to CON. The left PFC could be working harder to prevent fatigue in PPE. This could have implications for cognitive processes during and/or following exercise in the heat while wearing PPE. These data also suggest rapid and uncompensable Tc acquisition results in decreased cognitive control. This could have implications for individuals whose occupation requires PPE and critical decision making while experiencing rapid Tc heat storage. Lastly, these results show a difference between PPE and CON in regards to rate and magnitude of salivary cortisol appearance, potentially affecting individuals chronically exposed to acute heat stress. Increased acute cortisol concentration decreases anabolic response, cognitive performance, and mood states. The chronic effects of increased cortisol concentration are many: largely related to atherosclerosis development and subsequent cardiovascular disease. Additional issues include anthropometric, endocrine, metabolic, and haemodynamic disturbances. This study makes a strong argument for the rate of thermal acquisition factor. CON and PPE differences in PSI at all measurement points provides justification and support for the changes in other variables. Rapid and uncompensable Tc acquisition needs to be taken into account, as it potentially puts the lives of employees who wear PPE and those around them at risk. / Graduate

Alzheimer’s disease (AD), an age-related neurodegenerative disorder, progresses across a continuum of severity that leads to serious neurological dysfunction and eventually death. Initially manifesting as mild impairment in cognition and executive function, AD eventually leads to serious disturbances in memory, decision-making, language, mobility and sensing the environment. AD affects approximately 27 million people worldwide, over 5 million in the United States alone, and is one of the most debilitating diseases that costs society billions of dollars annually and is a primary cause of death in the elderly. Pharmacological treatments produce only moderate symptomatic benefits and do not attenuate or prevent the progression of AD with some medications associated with increased symptomatic behavior such as decreased motor function and increased likelihood of falls. Conversely, research utilizing animal models indicates exercise may play an important role to attenuate AD symptoms and delaying AD onset as regular aerobic activity increases the expression of brain-derived neurotrophic factor, a peptide that plays a major role in neural function, neural plasticity, and attenuation of neuritic plaque; a ß-amyloid derived plaque that is recognized as the primary cause of neural degradation associated with AD. To examine this exercise hypothesis, participants (N = 19; mean age 85.5 ±5.2 years) completed a single treatment, regular walking activity over time (30-min per day, 3 days per week for 12 weeks), with pre-test post-test evaluations undertaken utilizing valid research instruments designed to measure cognition, executive function, and motor capabilities in persons with AD. T-test with repeated measures ANOVA with various categorical variables as between-group factors were used to test the hypothesis. Analysis of change indicated significant change occurred in Cognitive function [t(18) = 5.74, p < .001], Balance [t(18) = 7.43, p < .001], and Mobility [t(18) = 3.82, p < .001], with no significant change in Activities of Daily Living (t[18] = 1.48, p < .156). A significant decrease in the number of falls was also found (z = 2.392, p < .017). No main effect was associated with AD stage, gender, or education level. The results of this study indicate regular aerobic activity enhances neural function in persons with AD, thus supporting the exercise hypothesis which posits regular aerobic exercise attenuates AD symptoms and delays AD onset. While the results provide important evidence regarding the impact of aerobic exercise on neural function in the AD populations, further research is necessary to identify the mechanisms by which brain-derived neurotrophic factor is induced with exercise and to examine the effectiveness of different exercise modalities (e.g., specificity, duration, and intensity) on neural function in the AD population. / Kinesiology