Inclusion criteria for CHD group :  - children with CHD included in the first study carried out from 2010 to 2015 6 and who have had at least 1 CPET 1 year after the first.  Inclusion criteria for control group :  children referred for a nonsevere functional symptom linked to exercise (murmur, palpitation or dyspnoea) or for a medical sports certificate. completely normal check-up, including physical examination, ECG, echocardiography and spirometry.  Exclusion criteria for control group:  Children with any chronic disease, medical condition (cardiac, neurological, respiratory, muscular or renal) Children with any medical treatment Children requiring any further specialised medical consultation