Geert Kleinnibbelink

Acute Cardiac Responses vs. Cardiac Remodelling 3 73 Statistical measurements Statistical analysis was performed using SPSS Statistics 25 (SPSS Inc., Chicago, IL, VS). All parameters were visually inspected for normality and tested with Shapiro-Wilk normality tests. Continuous variables were reported as mean ± standard deviation (SD) and categorical variables were presented as proportions. Paired-sampled T-tests were used to compare baseline and follow-up measurements, including echocardiographic indices, and to determine acute RV functional responses to exercise (augmentation in cardiac function between stress and rest echocardiography). Associations between acute RV functional responses to exercise (TDI s’, RVFWS, TAPSE, RVFAC) and chronic RV adaptation (RV basal diameter, RVmid-cavity diameter, RVEDA) were analysed by Pearson’s correlation coefficient, in which ‘acute’ is defined as the change in RV function from rest to exercise and ‘chronic’ as change in structure pre- versus post-training program. For all tests, we assumed statistical significance at p < 0.05. RESULTS Twenty-one participants were initially included in the study, of which six dropped-out (motivational issues n=4; health problems unrelated to the study n=2). Participants completed on average 30±2 training sessions (94% adherence) at an average 83.5% of their maximum HR. The fifteen participants who completed the study (22.0±2.4 years, ten men, 24.0±3.0 kg/m 2 ) showed a significant increase in VO 2 max/kg (52±7 to 56±7 mL/min/ kg, p < 0.001) ( Table 1 ). BMI and BSA did not significantly change (p > 0.05) ( Table 1 ). Mean SpO 2 during the individual 45 minutes high-intensity running exercise sessions of the hypoxic training program was 81±4%. At baseline, both right and left heart had normal geometry and all structural measurements were within normal ranges ( Table 2) . There were no abnormal 12-lead ECG findings.