Exercise tolerance predicts survival and mental health. To test benefits during adolescence for patients with pulmonary arteriovenous malformations (PAVMs) that cause hypoxaemia, we examined current and retrospective exercise tolerance aged 12y and 19y, linking to clinical records. In the 85 patients (65 female, mean age 56y), current metabolic equivalents ranged from 1.75 to 14.8
(mean 7.85) kcal.kg-1.min-1. Oxygen saturation explained only 2.2% of the variability. There were stronger associations between current exercise tolerance and anaemia indices, particularly the need for blood transfusions. In univariate and multivariate analyses, the
strongest anaemia-independent predictor was exercise tolerance aged 19y. In this cohort, the benefit associated with modestly increased activity by 19y (2.9 METs) was greater than the decrements from severe anaemia (~2.54 METs) or 3 decades of life (2.13 METs). The data support enhanced exercise for people with PAVMs, as for the general population, in preparation for later-life health challenges.