Adults with congenital heart disease have various degrees of impaired exercise capacity compared to healthy controls. Impaired exercise capacity makes everyday activities more difficult and demanding. There are few studies on effect of exercise training in adults with congenital heart disease. The hypothesis of this study is that structured home based exercise training will improve exercise capacity and health status in the studied population.

The number adults with congenital heart disease is increasing. Thanks to advances in the medical and surgical fields the number of adults with complex congenital heart disease is now higher than the children with corresponding heart disease. Though the long term prognosis is still unknown and continuously changing as new therapeutic options are introduced.

Persons with congenital heart disease have different degrees of impaired exercise capacity compared to healthy controls. Some studies indicate that this population is not sufficiently active to achieve the recommendations for physical activity in preventing acquired heart disease. Physical inactivity is an important risk factor for developing acquired heart disease and other life style diseases as obesity and diabetes. In a population where one or more previous cardiac surgeries are common, the prevention of life style diseases is especially important. Exercise training in heart failure and coronary artery disease is well studied and there are clinical guidelines. Regarding exercise training in adults with congenital heart disease, however,the information is sparse and further studies are needed.

Based on defined inclusion and exclusion criteria adults with complex congenital heart disease will be recruited in the Northern Health Care Region in Sweden and in Gothenburg. Before and after the twelve week intervention period the investigators will collect information about cardiopulmonary exercise capacity, health related quality of life, exercise self-efficacy, anxiety and depression. The patients will be randomized to twelve weeks of home based interval training or to a control group. The randomization ratio will be 2:1 (intervention:control). The control group will be instructed to continue with their habitual physical activities. The home based interval training program will be individualized based on the results of the exercise tests.

The aim of this study is to examine the effect of home based interval training on maximal and submaximal exercise capacity, quality of life, exercise self-efficacy, anxiety and depression.

Inclusion Criteria:

• Complex congenital heart disease (e.g.; Tetralogy of Fallot, Transpositions of the great arteries, Ebstein, Eisenmenger, Pulmonary atresia or Tricuspid atresia)
• Clinically stable without significant change the last 3 months
• Adult (>18 years)
• Informed consent

Exclusion Criteria:

• Signs of arrhythmia on exercise ECG or relevant clinical arrhythmia
• Mental retardation or psychiatric illness affecting the ability of independent decisions
• Other comorbidity affecting physical activity
• Other circumstances making participation unsuitable
• Present strategy of regularly executing physical exercise > 2 times/week in purpose to increase cardiovascular capacity.
• VO2 peak > 30 ml/kg/min
• No access to internet