Plasma nitrite reserve and vascular function before and after handgrip training in patients with heart failure

Abstract

There is a direct relationship between vascular health and physical function. The controllers of this relationship are unclear, but appear to involve biomechanical and biochemical influences on the vascular wall. Purpose: The purpose of this dissertation was twofold: (1) to explore the relationship between vascular health and physical function in three populations (elderly, young and chronic heart failure patients); and (2) to determine the modifying role of physical activity, inactivity and exercise training on controllers of this relationship. Methods: Four projects were designed to address 3 key issues in exercise vascular biology, including the influence of the pattern of blood flow on the vasculature; the effects of exercise training with blood flow restriction vascular function; and the influence of exercise training on vascular function in individuals with known disease. Results: Projects 1 and 2 indicate an increase in oscillatory shear within the vasculature with aging. This appears to be associated with lower physical function. Those individuals who maintain a higher amount of daily physical activity have more favorable blood flow pattern and higher vascular function. Project 3 indicates that localized exercise training with blood flow restriction dissociates vascular and muscle gains leading to enhanced muscular strength but diminished vascular function. The controller involved in the lower vascular function may be reduced shear stress during exercise. The controller that contributes to greater muscle strength during blood flow restriction remains unknown. Project 4 concludes that localized exercise training significantly improves vascular function and muscular strength in heart failure patients, although the gains are less than in age-matched individuals. The underlying controllers are unclear but may involve localized increases in shear stress and reduced oxidative stress. However, the benefits of exercise training are transient with vascular function returning to pre-training levels within 4 weeks after cessation of the training stimulus. Conclusion: These projects confirm a direct relationship between vascular health and physical function. This relationship is modifiable with physical activity levels and exercise training. It appears that intermittent shear stress, as seen with acute exercise, and oxidative stress serve as important stewards of the relationship between vascular and physical function.