Degree
Doctor of Philosophy (PhD)
Department
School of Kinesiology
Document Type
Dissertation
Abstract
Athletes are exposed to a multitude of stressors, including exercise, heat exposure, dehydration, and psychological stress, and their ability to maintain normal physiological functioning (physical resilience) is relevant to both health and performance. The purpose of this dissertation was to establish the effects of exercise in combination with different stressors on markers of physiological and metabolic function.
The first study investigated the effects of beverage consumption on metabolic and cardiovascular recovery during rehydration following exercise in the heat. Novel beverage consumption may expedite plasma volume recovery, but elevations in carbohydrate oxidation associated with glucose intake suppressed parasympathetic activity and the recovery of heart rate variability, in comparison to water.
The second study conducted waveform analysis on core temperature data in Division I American Football players during Fall training camp. Approximately one third of the trials indicated players reached a state of hyperthermia. Furthermore, greater maximum and average core temperatures were observed on the first two days of camp, perhaps due to the effects of acclimatisation. Repeated extreme exposure to heat and high training loads may increase heat storage at the end of camp but core temperature responses may be modulated by training load, fat mass, and fluid losses.
The third study investigated the effects of varying allostatic loads on exercise performance and resting and exercising metabolism in female collegiate athletes with high and low resilience. Adjusted resting energy expenditure decreased by 1.07 kcal/kg FFM/day from low to moderate and high allostatic loads in athletes with low resilience, accompanied by reductions in resting metabolic rate ratio, despite minimal changes to body composition. Moreover, high stress increased exercise-induced suppression of leptin and resting concentrations of FGF21, particularly in athletes with low resilience.
These three studies highlight the importance of managing stress in athletes to maintain normal metabolic functioning, particularly in athletes with low resilience, and propose novel strategies for evaluating stress and resilience. The presented studies demonstrate a need to continue developing strategies to quantify and control for various stressors in research, and better understand the heterogeneity in responses to stress.
Date
7-16-2024
Recommended Citation
Matthews, Rachel, "Metabolic Resilience in Athletes: Effects of Stress on Resting and Exercising Metabolic Function" (2024). LSU Doctoral Dissertations. 6570.
https://repository.lsu.edu/gradschool_dissertations/6570
Committee Chair
Johannsen, Neil