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

Abstract

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.

Peak Work Rate Increases With Lower Extremity‐Focused Exercise Training in Adolescents With Fontan Circulation

“…Other investigators have also studied the importance of the skeletal muscle pump in FC. 13 , 41 Pyykkonen recently demonstrated baseline associations between peak VO 2 and leg muscle mass assessed by bioimpedance in adolescents with FC. 13 Like our study, neither peak VO 2 nor leg muscle mass increased after a 6‐month training program; however, work tolerance increased in both studies.…”

“… 13 , 41 Pyykkonen recently demonstrated baseline associations between peak VO 2 and leg muscle mass assessed by bioimpedance in adolescents with FC. 13 Like our study, neither peak VO 2 nor leg muscle mass increased after a 6‐month training program; however, work tolerance increased in both studies. In Pyykkonen's study, the association between peak VO 2 and leg muscle mass was maintained with training.…”

“…Multiple studies have demonstrated the safety and feasibility of hospital‐based programs as well as the incorporation of home training. 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 Previous investigators have achieved various improvements in peak VO 2 , cardiorespiratory function, physical activity levels, and quality of life. However, programs have varied by exercise type (aerobic, resistance, and inspiratory muscle training), duration, setting, parental involvement, age and Tanner stage at training, and targeted mechanism; therefore, the optimal training regimen remains unknown.…”

“…While we did not demonstrate increased muscle mass with training, higher work rate may reflect increased muscle fitness and strength, 15 as in Pyykkonen's study where exercise training resulted in increased work rate and muscle strength measured by standing long jump and shuttle run test. 13 Future studies should investigate the effect of these improvements in strength on disease progression and symptoms. Additional work is needed to understand whether interventions to augment muscle mass and strength earlier in childhood could improve anaerobic power and overall fitness before many patients with FC decline in adolescence and young adulthood.…”

“… 3 , 4 A small study of adult patients with FC demonstrated improvements in skeletal muscle mass and peak VO 2 with resistance exercise training, 5 suggesting that muscle deficits may be modifiable determinants of exercise performance in the FC. Small pediatric studies have demonstrated some improvements in exercise performance and quality of life with various training regimens, 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 but few studies have addressed the physiologic adaptations that result from exercise training in children with FC. To our knowledge, no study has examined the effect of exercise training on lower extremity skeletal muscle mass and other noncardiac factors influencing exercise performance in youth with FC.…”