Inclusion Criteria:  Age ≥ 18 years Being hospitalized for rehabilitation because of a severe form of the COVID-19 that required an admission in intensive care unit for acute distress respiratory syndrome treated by mechanical ventilation. Being beneficiary of the French social security.  Exclusion Criteria:  Person requiring supplementation in oxygen > 4 L/min because above this threshold, the oxygen flow is considered to be associated with an increased risk of aerosolization and further virus spread in patient being contagious; Oxygen desaturation during exercise (i.e., SpO2 < 90%) and requiring supplementation in oxygen > 4 L/min. Person showing a lower motor neuron disease as defined by the medical research council score < 48/60 including hyporeflexia (quadricipital and triceps tendons) and decrease in lower limb sensation. Persons showing denervated muscle (including quadriceps, hamstring, gluteus and triceps) confirmed by electromyography because the electrical stimulations delivered by the stimulator (i.e., symmetric and rectangular biphasic currents) are not appropriate to restore a pedaling movement; Person with osteo-articular disease at lower limbs including reduction in range of motion at the hip, knee and ankle preventing cycling pedaling in a sitting position; Persons with associated neurologic or psychiatric disease; Person with a medical contraindication to intensive rehabilitation; Person suffering from suspected or diagnosed epilepsy; Person with an implanted device; Person included in another ongoing research or during an exclusion period of another research; Adults protected by law (guardianship or curatorship); Pregnant women