Sickle cell disease (SCD), the most common genetic disease worldwide and in France, is an inherited haemoglobinopathy characterised by chronic haemolytic anaemia, vaso-occlusive crisis (VOC), acute pain, and multi-organ damage. Due to anaemia and multiple pulmonary, cardiac, endothelial, muscle, and metabolic dysfunctions, fatigue and poor physical capacity are common in SCD patients and constitute the primary reason for a sedentary lifestyle. However, recent findings demonstrated in the first randomised, controlled, and prospective study implementing endurance training in SCD that, when adequately calibrated, regular moderate-intensity endurance training is not only safe but also beneficial for patients (primary outcome: improvement of physical ability). This pivotal randomised, controlled, prospective study is designed to prove, on a large multicentre cohort, adult and paediatric, including patients with complications and over a longer period (one year). The objective of the study is to demonstrate the efficacy of participating in a program of regular physical activity to reduce the rate of vaso-occlusive crises requiring hospitalisation and to improve physical ability in patients with SCD.