Geert Kleinnibbelink

Chapter 3 68 the RV strain-area loop compared to exercise under normoxia. 13 These echocardiographic markers support indirectly the presence of an increase in pulmonary artery pressure, and therefore, RVafterload. Accordingly, hypoxicexercisemayexaggerate thedisproportionate elevation in wall stress for the RV versus LV during exercise and may therefore lead to more rapid adaptations in the RV to exercise training allowing us to further explore our hypothesis. METHODS Study population Twenty-one healthy individuals (fourteen males) were recruited for the study. Participants were eligible to take part in this study if they were able to run on a treadmill and that they did not engage in sport-related exercise for more than two hours a week at moderate- to-high intensity for the last six months. Exclusion criteria were a body mass index (BMI) < 18 or > 30 kg/m 2 , any possibility of pregnancy, personal history of cardiovascular disease, a family history of cardiovascular death ( < 55y), exercise-limiting respiratory disease, physical (i.e. musculoskeletal) complaints making completion of the 12-week training program impossible, abnormal resting 12-lead electrocardiogram (ECG) and abnormalities observed on resting transthoracic echocardiography. The procedures were performed in accordance with institutional guidelines and conformed to the declaration of Helsinki. The study was approved by the Ethics Research Committee of the Liverpool John Moores University (18/SPS/065). Participants gave full written and verbal informed consent before participation. Study design In this prospective study, participants attended the laboratory on 35 separate occasions, see Figure 1 . During the first visit, a medical screening was performed to determine eligibility of the potential participants. After signing informed consent, baseline measurements including echocardiographic assessment at rest were performed under normoxic conditions (FiO 2 20.9%). During visit 2, after 30 minutes of acclimation echocardiographic assessments at rest and during stress under hypoxic conditions (FiO 2 14.5%) were performed. These assessments were obtained in order to relate acute