What is the relation between aerobic capacity and physical activity level in adults with congenital heart disease?

Background: Aerobic capacity (AC) in adults with congenital heart disease (CHD) is often reduced, mainly due to low confidence levels towards physical activity (PA). The main objective of this study was to estimate the association between PA level and AC (measured as peak of oxygen consumption, VO_2peak) in adults with CHD. Methods: A total of 183 individuals (83 women and 100 men; mean (SD) age 36.9 (11.0) years old) from Vall d’Hebron Hospital, Barcelona-Spain in 2019, participated in this cross-sectional study. The AC was assessed by cardiopulmonary exercise testing (CPET) using a treadmill ramp protocol. Considering values of metabolic equivalent of task (MET, MET-min·week^-1) obtained by the short International Physical Activity Questionnaire (IPAQ), participants were divided into three categories of PA: health-enhancing PA (HEPA), minimally active, and inactive. Results: Median (SD) PA was 2737.2 (2835.7) MET-min·week^-1, with 60 participants (32.8%) reporting HEPA, 91 (49.7%) minimally active, and 32 (17.5%) inactivity. Participants demonstrated a mean VO_2peak of 28.9 (8.8) mL·Kg^-1·min-1, showing AC values on average 13% lower than expected in a healthy population. Overall, PA and AC were positively associated. Adjusting for sex and age, an increase of 1000 MET-min·week^-1 was associated with an increase in VO_2peak of 0.8 units (95% CI 0.4–1.2; p < 0.001). There were no differences in the degree of increase between sexes (p = 0.427). Conclusion: These findings suggest that an increase in PA in patients with CHD significantly improves their AC, and hence, could be recommended when the goal is to improve their physical condition.