Date of Award

2016

Document Type

Open Access Dissertation

Department

Exercise Science

Sub-Department

Norman J. Arnold School of Public Health

First Advisor

Clemens Drenowatz

Abstract

Within the United States, 68% of all adults have been classified as overweight to obese, as defined by 25 kg/m2 ≤ BMI ≤ 35 kg/m2. Research has shown that overweight/obese individuals can still gain health benefits through participation in aerobic activity without losing weight. These improvements include improved glucose control, CRF, HDL and quality of life. More research is necessary to understand the health benefits associated with a chronic aerobic intervention under weight stable conditions. We therefore examined the health benefits of an aerobic 6-month intervention under weight stable conditions on body composition, cholesterol and measurements of appetite and satiety on young, previously sedentary adults.

This dissertation is comprised of three study aims that were designed to 1) determine a possible association between an increase in energy expenditure and body composition and fitness; 2) examine the association between changes in energy expenditure and body composition to produce alterations in blood lipids and C-reactive protein; 3) analyze an association between changes in energy expenditure and body composition on objective and subjective measurements of appetite. Data used in these studies was drawn from the Energy Flux Study, a randomized controlled trial completed in Columbia, SC involving young, previously sedentary adults (n=81). We determined energy expenditure over a 10-day wear period using SenseWear mini armbands at baseline and upon intervention completion. Body composition (primarily fat mass and fat free mass) were measured using a dual X-ray absorptiometry scanner (DXA), percent body fat was determined using %BF= (total fat/body weight). Graded exercise tests (GXT) used a modified Bruce protocol in which participants worked to volitional fatigue on a motorized treadmill. Blood was collected from an antecubital vein in either EDTA (1.25 mg/dL) and/or aprotinin (500 TU/mL) tubes (dependent on analyses). The exercise intervention had participants complete between 3-6 exercise sessions per week for approximately one hour at 70-75% VO2max HR for 6 months. Throughout the intervention, participants were required to maintain their weight ±3% of their baseline body weight.

Study 1 found female participants showed improvements in their body composition with increases in vigorous activity only. While no other significant changes were seen in body composition through increases in energy expenditure, those who participated in an exercise program increased their cardiorespiratory fitness.

Study 2 found a decrease in fat mass through participation in an aerobic intervention will improve cholesterol levels as compared to changes in EE. This was further identified in those who displayed a beneficial change in their lipid profile. Those individuals who improved their lipid profile showed a greater decrease in FM as compared to the group who worsened their lipid profile.

Study 3 found a decrease in fasting and non-fasting leptin in male and female exercise participants from baseline to follow-up. Females showed a significant decrease in fat mass and percent body fat at 6-months. Changes in FM were significantly associated with fasting and non-fasting leptin in males only. Limited significance is seen in subjective measures for appetite and hunger.

Rights

© 2016, Molly Madison DeMello

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