Geert Kleinnibbelink

Chapter 1 26 General aims of this thesis Using echocardiography and adopting novel techniques such as speckle tracking echocardiography and the strain-area loop, we aimed to investigate acute and chronic effects of load challenges on right ventricular structure, function and mechanics. In the first part, we focused on the physiological cardiovascular effects of acute and chronic exercise in healthy individuals and elite athletes. Thereby, we explored whether acute effects were related to chronic cardiovascular adaptations. In the second part, we focused on altered haemodynamics and exercise in patients with PH. Outline of this thesis Acute and long-term responses to exercise have traditionally focused on changes in the LV. To better understand adaptation of the RV, the focus of the first part of this thesis is the impact of acute exercise bouts and regular exercise training on the RV in healthy individuals and elite athletes. In Chapter 2 , we first examined the effects of acute exercise on RV function. Using a randomized cross-over design, we tested the hypothesis whether exercise under hypoxia vs. normoxia induced EICF to a greater magnitude during and following relatively short duration, high-intensity exercise. As hypoxia induces pulmonary vasoconstriction resulting in a higher afterload and therefore higher workload of the RV, the influence of afterload on EICF could be investigated. Secondly, these observations in relation to acute exercise were extended to regular exercise training. In Chapter 3 , we examined the impact of a 12-week hypoxic endurance exercise training program on right- and left-sided cardiac structure, function and mechanics in healthy individuals. In addition, we explored if pre-training changes in cardiac responses to acute exercise are related to structural adaptation after 12 weeks of hypoxic endurance exercise training. In Chapter 4 , we examined the impact of an increase in training volume across 9-months in Olympic rowers on left- and right-sided cardiac structure, function and mechanics, and explored potential sex differences. In addition to the direct effect of (acute) exercise on cardiac remodelling, we also linked (acute) exercise to blood pressure. In Chapter 5 , we examined the acute and chronic effects of high-intensity exercise in hypoxia on blood pressure and post-exercise hypotension.