Geert Kleinnibbelink

Chapter 10 202 24 , oxidative stress 25 , β -adrenergic receptor downregulation in response to sustained elevations in circulating catecholamines 26, 27 and post-exercise alterations in loading and heart rate. 5 These factors may have independent or synergistic roles in the development of EICF. These mechanisms remain poorly understood. One potential explanation is a lack of EICF studies which specifically address this question, possibly due to the field-based (and entirely human model) setting in which EICF was studied. This limits studies to control for a single factor contributing to the development of EICF. Nevertheless, EICF is highly likely to be multifactorial. This thesis shows that with use of environmental factors (i.e. hypoxic environment), a controlled study to a specific mechanism of EICF can be conducted. Further research should not only investigate the direct relation between EICF and long-term outcome but also investigate these multifactorial causes, ideally per single factor, to develop a greater understanding of the (patho)physiological mechanisms and nature of EICF. 10.1.2 – Post-exercise hypotension Evaluation of blood pressure during or following exercise may have clinical relevance. Usually, blood pressure will drop temporarily post-exercise, for several hours to days, and is typically referred to as post-exercise hypotension (PEH). 6, 28, 29 This may be explained by a decrease in total peripheral resistancewhich is not compensatedby adequate elevations in cardiac output. In Chapter 5 , we demonstrated that the magnitude of PEH during the first bout of 45-minute high-intensity running exercise was positively related to themagnitude of the BP-lowering effect of 12-weeks high-intensity running exercise training under hypoxia ( Figure 1C ). This is in line with previous studies that showed that the magnitude of PEH relates to the blood pressure lowering effect of exercise training in healthy and pre-hypertension middle-aged individuals. 8, 30, 31 Previously, it was demonstrated that a hypertensive blood pressure response during exercise predicts future development of hypertension in young athletes and predicts cardiovascular death in middle-aged men. 32, 33 These observations underscore that studying the cardiovascular systemduring and after the haemodynamic stress of exercise provides a wealth of valuable information. Although further work is required, presence of PEHmay be used as a proxy to identify ‘responders’ to the blood pressure lowering effects of exercise training. Such approaches may contribute to personalised healthcare and enlarges successes of treatment strategies.