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.

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Background: Cardiopulmonary exercise testing with lactate and ammonia samples is used in the diagnostics of metabolic myopathies. As the effect of age and sex on the exercise lactate and ammonia levels are incompletely characterized for clinical associations, our aim was to assess the effects of these factors on healthy subjects to improve the test's interpretation. Methods: Seventy-three subjects (34 men and 39 women; age < 35 years, n = 26, 35-50 years, n = 23 and >50 years, n = 24) performed cardiopulmonary exercise tests with venous blood gases, plasma lactate and ammonia analyses at rest, during exercise, and 2, 4, 6, 10, 20 and 30 min into recovery.Results: The lactate (p = 0.021-0.044) and ammonia values (p = 0.002-0.038) differed between men and women measured during recovery and between three age groups point-by-point in maximal exercise and the recovery phase and also longitudinally, most notably between <35-and >50-year-groups (lactate p = <0.001-0.040, ammonia p = 0.002-0.03). In the linear model, the yearly reduction of lactate was maximally −0.119 mmol/L and that of ammonia −1.514 µmol/L. The yearly reduction of lactate was greater in women than in men (−0.131 vs.−0.099 2 min into recovery), but for ammonia, the results were not as clear.Conclusions: Plasma lactate and ammonia concentrations measured during cardiopulmonary exercise were lower in older age groups, and their yearly reduction was also influenced by sex. These data give new information on lactate and ammonia levels and the effect of aging on them during exercise and recovery and may help assess cardiopulmonary exercise testing results.