Date of Award

2022

Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy in Integrative Physiology (PhD)

Administrative Home Department

Department of Kinesiology and Integrative Physiology

Advisor 1

William Cooke

Advisor 2

Zhiying Shan

Committee Member 1

Steven Elmer

Committee Member 2

Kui Zhang

Abstract

Introduction: Despite the commonality of fasting, there still remains a lack of scientific research, specifically in regard to the impact of fasting on cardiovascular physiology. Thus, the goal of this research project was to further explore the relationship between fasting and cardiovascular physiology. Hypothesis: The hypothesis of this research project was that a 24-hr fast would likely lead to increased BP and HR, along with blood biomarker changes, and that experiencing this 24-hr fast twice a week would lead to reduced BP and HR along with altered circulating blood biomarker levels. Methods: In order to test these hypotheses, cardiovascular and blood biomarker factors were assessed both before, during and after a 24-hr fast, and throughout a 4-wk period of two 24-hr fasts per week. Results: After the 24-hr fast there was increased resting BP (SBP, p=0.062; DBP, p=0.101) and HR (p=0.125), in addition to decreased overall average ambulatory BP (SBP, p=0.159; DBP, p=0.167) and HR (p=0.076) throughout the 24-hr fast. Blood glucose (p=0.012) and plasma NPY (p=0.007) were decreased, and plasma ghrelin (p=0.171) and plasma LEAP2 (p=0.203) were increased after the 24-hr fast. Resting BP (SBP, p=0.004; DBP, p=0.202) was decreased, and autonomic function showed a shift toward lessened sympathetic activity (↑ RRI, p=0.125; ↓ RRI-LF/HF ratio, p=0.293) at the end of the 4 weeks of fasting, and the decrease in BP was seen as early as 2 weeks of fasting. Plasma ghrelin (p=0.372) was increased at the end of the 4 weeks of fasting with little to no change in blood glucose (p=1.000), plasma LEAP2 (p=1.000) and plasma NPY (p=1.000). Plasma LEAP2 (p=0.693) and plasma NPY (p=0.473) did decrease after 2 weeks of fasting before returning to approximately baseline levels after 4 weeks of fasting. The cardiovascular changes from 24 hours of fasting were most correlated to blood glucose and plasma ghrelin, and the changes from 4 weeks of fasting were most correlated to plasma ghrelin and plasma NPY. Discussion: It appears that fasting may have a mild impact on cardiovascular physiology; both during a 24-hr fast and as an adaptation to 4 weeks of fasting.

Download

Share

COinS