Abstract
Global prevalence of obesity and type 2 diabetes mellitus continue to rise, increasing health burden particularly for cardiovascular and metabolic conditions. Exercise is a powerful stimulus to improve cardiorespiratory fitness, insulin sensitivity, and vascular health, yet individual responses to exercise are variable and may be affected by hormones, exercise intensity, obesity status, and medications. For this three-manuscript dissertation, manuscripts 1 and 2 are sub-analyses from an NIH-funded R01 grant exploring the impact of acute exercise intensity and obesity status on ghrelin concentrations, endothelial function, and appetite. They each utilize a repeated-measures, within-subject design with 3 conditions (non-exercise control, moderate-intensity exercise, and high-intensity exercise), where brachial artery flow-mediated dilation, ghrelin concentrations, and subjective appetite ratings were collected at baseline and at several timepoints. Manuscript 3 is a double-blind, placebo-controlled, crossover pilot study investigating the impact of metformin on lactate levels and exercise capacity during cycle ergometry in young, active adults. The trial includes 2, 19-day treatments of metformin and placebo. After each treatment, participants performed incremental exercise tests and time-to-exhaustion bouts. This project sought to identify if metformin impacted lactate threshold during exercise as the first known study to make this mechanistic link in recreationally active adults. This dissertation provides an overview of each manuscript along with a short literature review and detailed manuscripts.
