Inclusion Criteria:  chronic, incomplete SCI (> 1 year, AIS B-D) traumatic or non-traumatic lesion capacity to stand up and perform a 10MWT with or without medical aids partially wheelchair dependent intact lower motoneuron on the segmental innervation level of M. glutaeus maximus, Mm. ischiocrurales, M. tibialis anterior and M. quadriceps (to guarantee the stimulability with FES)  Exclusion Criteria:  Exoskeleton device related contraindications: > 100 kg body weight; Body height: < 155 cm or > 190 cm; pelvic width: > 46 cm orthopedic limitations (acute fractures of the lower limb) contractures heterotrophic ossification spasticity (modified Ashworth Scale >3) skin injuries of the lower limbs in areas where the skin has contact with the exoskeleton Unstable circulation (unable to stand for at least 10 minutes) acute deep vein thrombosis pregnancy (tested in women of childbearing age (15 - 49 years))