Geert Kleinnibbelink

General Discussion 10 201 Rest echocardiography Stress echocardiography Exercise-induced cardiac fatigue not present Exercise-induced cardiac fatigue present 45-minute high-intensity running exercise Figure 2. Exercise-induced cardiac fatigue after a bout of 45-minutes high-intensity running exercise is not present when evaluating with rest echocardiography but present when evaluated with stress echocardiography. Meaning of exercise-induced cardiac fatigue It is currently unclear whether EICF is a physiological or pathophysiological phenomenon. It has beenhypothesized that excessive exercise training (trainingwhich is too intense and/ or recovery is too short) leads to repetitive occurrence of EICF that may act as a stimulus for maladaptive remodelling ( Figure 1B ). 9, 20 However, associations between these acute exercise changes and long-term cardiovascular changes remain unknown. To understand this link, studies need to adopt a prospective design in a large cohort of individuals. However, besides studying the direct association between EICF and long-term outcome, it is important to examine the direct (patho)physiological mechanism involved. In Chapter 2 , we demonstrated that an additional RV afterload, induced by hypoxia (FiO2 14.5%), did not exaggerate EICF after 45 minutes of high-intensity running exercise. This suggests that (after)load dependency may be less important as a contributing factor to EICF in short duration exercise as previously suggested. 21, 22 Other suggested factors that may be implicated in the development of EICF are subclinical levels of cardiomyocyte damage 23,