Left and right ventricular volumes and stroke volumes at rest and exercise. Upper panel shows no changes in left ventricular end-diastolic volumes (A) and a small but significant decrease in end-systolic volume (B), leading to an increased stroke volume (C). Lower panel show a significant decrease in right ventricular end-diastolic volume (D) and end-systolic volume (E). Right ventricular stroke volume increased during exercise, however not statistically significant (F). Error bars denote mean and standard error of the mean (SEM).