Date of Award

2017

Document Type

Open Access Dissertation

Department

Exercise Science

Sub-Department

The Norman J. Arnold School of Public Health

First Advisor

J. Larry Durstine

Abstract

Cardiorespiratory fitness (CRF) is well established as having a strong inverse association with numerous cardiovascular disease (CVD) risk factors and mortality. As CVD remains the number one cause of death in America, the detrimental effects of low CRF present a substantial health threat. The studies presented in this dissertation syndicate both epidemiologic and clinical data that will enrich the knowledge base regarding the magnitude of change in CRF in relation to CVD risk factors.

Recently, the American Heart Association established a new construct termed ideal cardiovascular health (CVH), which is characterized by seven metrics known as Life’s Simple 7. The concept emphasizes seven positive health factors and behaviors. The promotion of achieving and retaining these metrics at an ideal level serves to improve CVH and decrease public health burden and CVD mortality. This first study of this dissertation found that higher levels of CRF are strongly associated with better CVH profiles, which was demonstrated by individuals with moderate and high CRF exhibiting almost 11 and 40 times greater odds of having average or optimum CVH scores, respectively, compared to low fit individuals. Additionally, longitudinal analyses showed that improvements in CRF over time are associated with significant improvements in CVH score. These findings support the vital role CRF plays in public health efforts aiming to prevent the development of CVD and reduce CVD mortality risk.

Secondly, this dissertation investigated the responsiveness of CRF, as measured by maximal oxygen consumption (V̇ O2max), and CVD risk factors following aerobic exercise intervention. Aerobic exercise interventions are used to increase CRF in order to help combat the detrimental effects of low CRF. However, relying solely upon group mean changes can be misleading as considerable inter-individual variation exists in the ability to improve CRF and CVD risk factors to standardized interventions. This study is likely the first assess the prevalence of V̇ O2max responsiveness across 14 diverse exercise interventions. Although the exercise interventions produced significant mean increases in V̇ O2max, evaluation of individual changes in V̇ O2max revealed that 34% of the total sample was considered low V̇ O2max responsive. Within studies that employed multiple exercise interventions, a trend emerged. As exercise amount and intensity increased within studies, prevalence of low V̇ O2max response decreased. The utility of these responsiveness cutpoints helps to provide a better understanding of the interindividual variation in response to exercise training to enhance our ability to provide personalized exercise prescription for improved health and attenuated CVD risk.

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