Exercise Prescription Enhances Maximal Oxygen Uptake and Anaerobic Threshold in Young Single Ventricle Patients with Fontan Circulation

A modified Fontan procedure is performed to palliate single ventricle malformations. This hemodynamic arrangement sets systemic venous pressure unphysiologically high which predisposes the patient to severe long-term complications. As a means of self-care, exercise may ease transpulmonary flow. We investigated the effects of 6-month exercise prescription on pediatric Fontan patients. Eighteen stable Fontan patients (14 ± 2.6 years, 160.4 ± 11.3 cm, and 51.4 ± 14.4 kg) were recruited. Baseline fitness was assessed by physical activity questionnaire, body composition, cardiorespiratory performance, and muscle fitness tests. Exercise prescription was individually tailored for a 6-month training period at home. At entrance to the study, Fontan patients had lower than normal maximal oxygen uptake (VO2max) of 28. ± 5.9 ml/kg/min (61 ± 11% of normal). VO2max significantly correlated with weekly amount of habitual exercise and muscle mass of the lower limbs (p < 0.001 for both). After 6 months of training, the patients had improved their anaerobic threshold of 18 ± 3.5 vs 20 ± 4.8 ml/kg/min, p = 0.007, and workload tolerance of 119 ± 39 vs 132.4 ± 44 W, p = 0.001. At EUROFIT tests, the patient muscle fitness was below age-matched reference, but correlations existed between VO2max and lower limb muscle tests. Our patients with Fontan hemodynamics were able to positively respond to an exercise program by enhancing submaximal performance which should be beneficial for getting through daily activities. Future studies should correlate whether hemodynamic findings at Fontan completion influence physical activity and exercise reserves, and whether these predict predisposition to chronic complications.