Fontan Group Inclusion Criteria  be between the ages of 8-50 Having undergone Fontan operation in our hospital or another center Clinical stability of the patients (preserved ventricular function), No change in ongoing drug therapy that adversely affects clinical stability, At least 1 year after the operation and to be followed in the Pediatric Cardiology Polyclinic of our hospital  Fontan Group Exclusion Criteria:  Inability to access the patient's medical data Neurological and/or genetic musculoskeletal disease Having orthopedic and cognitive problems that prevent testing The patient's and/or family's unwillingness to participate in the study  Control Group Inclusion Criteria:  Not have cardiovascular, neurological and/or genetic musculoskeletal disease Not having orthopedic and cognitive problems that prevent testing The patient's and/or family's willingness to participate in the study