Inclusion criteria for experienced users of prosthesis - intervention group:  Unilaterally amputated (above the ankle joint / under the hip joint) Minimum 12 months since amputation Have a well-adapted prosthesis before baseline measurements Not attended an organized, regular training program for the last 6 months Uses the prosthesis on a daily basis Participation approved by physician  Inclusion Criteria for experienced users of prosthesis - control group:  Unilaterally amputated (above the ankle joint / under the hip joint) Minimum 12 months since amputation Have a well-adapted prosthesis before baseline measurements Daily use of the prosthesis Not attended an organized, regular training program in the last 6 months No participation in regular and systematic training between pre- and post-testing  Inclusion Criteria for new users of prosthesis:  Unilaterally amputated (above the ankle joint / under the hip joint) No prior record of use of prosthesis Participation approved by physician  Exclusion Criteria:  Bilaterally amputated over ankle joint Lack of understanding of Norwegian language (oral, written) Neurological disorders affecting gait function Skin lesion or abrasion on the stump or remaining extremity affecting mobility and function Other issues that complicate participation in a rehabilitation intervention