Congenital heart disease (CHD), the most common birth defect, is present in nearly 1% of the population. CHD patients are associated with intense resource utilization and premature death in adulthood. The risk of premature death is linked with reduced exercise capacity, a finding consistently noted in youth with CHD. Reduced exercise capacity in this population has also been associated with reduce physical activity and health-related quality of life.

Cardiac rehabilitation (CR) in adults with acquired heart disease is an established secondary prevention strategy that improves exercise capacity. The investigators propose a prospective clinical trial of a home-based high intensity interval training (HIIT) program using a novel telemedicine-equipped video game-linked cycle ergometer (MedBIKE™) for 10 to 18 year olds with repaired moderate-complex CHD. The pilot study with the MedBIKE has shown promising results. The investigators now seek to study the efficacy of this program in a broader CHD population.

Purpose: This project is a prospective clinical trial of a home-based high intensity interval training (HIIT) exercise program using a novel telemedicine-enabled and video game-linked customizable cycle ergometer (MedBIKE™) in the pediatric congenital heart disease (CHD) population.

Hypothesis: The home-based the MedBIKE™ HIIT program will significantly improve exercise capacity. The MedBIKE intervention will significantly improve time spent in MVPA and reduce sedentary time, improve HRQoL and self-efficacy towards PA, and improve endothelial function. Moreover, the investigators hypothesize that the improvements in exercise capacity, along with the improvements in the secondary outcomes will remain significantly improved up to one-year post- MedBIKE intervention, when compared to pre-intervention values.

Justification: Exercise intervention studies in the pediatric CHD population have been limited by small sample sizes and there is limited data pertaining to the sustained effects of exercise interventions on exercise capacity, physical activity, endothelial function, and quality of life. This study, using standardized and largely operator-independent measure, will be one of the largest exercise intervention clinical trials in the pediatric CHD population.

Primary Objective: Evaluate the impact of an eight-week, home-based HIIT MedBIKE™ program on exercise capacity in youth with repaired moderate-complex CHD.

Secondary Objectives: Evaluate the impact of the MedBIKE™ intervention on 1) PA; 2) HRQoL and self-efficacy towards PA; 3) endothelial function; and 4) sustained changes in the primary and secondary outcomes.

Research Method: This will be a single-center, prospective clinical trial. Potential participants and families will be approached first by a clinical team member. In addition, flyers with key study information will be placed in waiting rooms of the pediatric cardiology clinics. Participants and parents expressing interest will meet with a research coordinator who, along with one of the investigators and the clinical team will screen for eligibility. Written consent and assent (if applicable) will be obtained from participants who are deemed eligible.

Following recruitment, participants will be administered the TACQOL and CSAPPA questionnaires and an accelerometer to be worn for 7-days, after which participants will arrive for the baseline assessment. As participants must be NPO for EndoPAT testing, they will have a small meal following EndoPAT testing and at least two hours prior to CPET testing. A MedBIKE will be installed in the participants home within 2-weeks of the baseline CPET at which time an orientation session will occur to review the manual, safety procedures and the telemedicine component. Participation will consist of a 12-week, 3-times per week (36 sessions in total) HIIT program. All sessions will be supervised by an exercise physiologist. Protocol completion will be considered a minimum of 27 of the 36 sessions (75%). Following the completion of the intervention, the MedBIKE will be removed by the participants home and returned to the Stollery Children's Hospital.

A follow-up assessment, identical to that of the baseline (questionnaires, EndoPAT, CPET, interviews and a 7-day week wear of an accelerometer) will occur 3-14 days post-intervention. These assessments will be repeated at 6- and 12-months post-intervention.

Inclusion Criteria:

• Children and adolescents aged 10-18 years
• Repaired moderate-complex congenital heart disease

Exclusion Criteria:

• Non-English speaking (thus limiting communication during the MedBIKE™ sessions)
• Home environment cannot accommodate the MedBIKE™ system (space limitations)
• Previous involvement in a cardiac rehab or exercise intervention program
• Primary cardiologist has exercise restricted the participant or counsels against participation
• Previous exercise stress test demonstrating sustained arrhythmias, ST segment elevation or depression greater than 3mm, an inappropriate rise in blood pressure (BP) (<20 mmHg) or a systolic BP >200 mmHg, or symptoms of chest pain or syncope
• Resting arterial saturation <85% or oxygen requirements
• Moderate ventricular systolic dysfunction (or worse) at the most recent echocardiogram
• History of chest pain on exertion
• Unrepaired/unpalliated CHD
• Arrhythmias in the last year (including supraventricular tachycardia, ventricular tachycardia, atrioventricular block (Mobitz II or worse))
• New York Heart Association class II or worse symptoms
• Active medical inter-current illness limiting ability to participate
• Cognitive impairment limiting the communication needed for the HIIT program
• Extracardiac or congenital abnormality limiting the participant's functional ability to exercise

Individual participant data will not be shared with other researchers. All data will be de-identified prior to analysis and published.