Identifier

etd-03272008-152354

Degree

Doctor of Philosophy (PhD)

Department

Kinesiology

Document Type

Dissertation

Abstract

The goal of this research was to gain a better understanding of interplay between molecular biology, physiology, biochemistry, functionality with disease and interventions. The primary findings of the first study were that there was a significant inverse correlation between homocysteine and brachial artery flow mediated dilation (BAFMD) and baseline brachial artery diameter. Interestingly, there was a significant difference in BAFMD between methylene tetrahydrofolate reductase (MTHFR) genotype groups. Regression analysis indicated that the MTHFR genotype, homocysteine and age were significant predictors of BAFMD. The second study revealed that vascular reactivity as measured by BAFMD was modifiable. A meta-analysis of 22 intervention studies showed that exercise training produced significant changes in BAFMD. Fifteen of the twenty-two intervention groups had a statistically significant improvement in BAFMD. Only one study had a negative effect size (ES). Larger changes in BAFMD were seen in “at risk/diseased” subjects compared to healthy subjects. Shorter duration studies (< to 8 weeks) had a larger mean ES than did longer duration studies. In regards to training type the aerobic group had the largest ES. The meta-analysis revealed that physical training produces a large change in BAFMD, a biomarker of vascular health. Finally, study three revealed that middle-aged men and women instructed to consume a low-fat diet, reported, within 3 months, significant reductions in total fat, saturated fat, and cholesterol intake, which corresponded with a moderate, yet, significant change in LDL-cholesterol. However, the diet intervention appeared to have only a modest effect on lipid balance as indicated by small reductions in the total cholesterol/HDL-cholesterol and LDL-cholesterol/HDL-cholesterol ratios. Additionally, a clustering of lipid and vascular responses were seen indicating the array of responses to dietary interventions. Gene-diet interaction evaluation did reveal that genetic polymorphisms, such as the deletion at the apolipoprotein B signal peptide (24 amino acids) may be associated with varying responses to low-fat dietary interventions. Interestingly, the data suggest that despite self-reported reductions in total fat, saturated fat, and cholesterol intake, markers of vascular “health” were not significantly changed. However, individuals’ brachial artery reactivity increased by 3 months in both groups, which persisted throughout the trial.

Date

2008

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Michael Welsch

Included in

Kinesiology Commons

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