Assessment of aerobic capacity and walking economy of transfemoral amputees

Background: Studies of the maximal oxygen uptake (VO2max) of transfemoral amputees have mostly used protocols that activate a relatively small muscle mass. Consequently, transfemoral amputee VO2max may be systematically underestimated, and the validity of these test protocols is questionable. Objectives: (1) Investigate validity and reliability of a VO2max walking protocol and (2) compare the VO2max of a transfemoral amputee group with a group of matching controls. Study design: (1) Randomized crossover study: walking versus running VO2max for the control group and (2) case-control study: transfemoral amputees versus control group VO2max. Methods: Twelve transfemoral amputees and control participants performed a walking VO2max test with increasing treadmill inclinations to voluntary exhaustion. The control group also completed a running (“gold-standard”) VO2max test. Results: Mean (standard deviation) control group VO2max following walking and running was similar, that is, 2.99 (0.6) L min−1 and 3.09 (0.7) L min−1, respectively. Mean (standard deviation) transfemoral amputee walking VO2max was 2.14 (0.8) L min−1 (compared to CON; p < 0.01). Mean intraclass correlation coefficient of repeated VO2 measurements was 0.97, and within-subjects standard deviation was 60 mL min−1. Conclusions: The walk protocol is valid. Walking VO2max of transfemoral amputees was 40% lower compared to control group. Reliability of the walking protocol is comparable to other walking protocols. Clinical relevance The design, alignment, and materials of prostheses are important for effective ambulation. Cardio-respiratory fitness is, however, also important in this regard, and a low fitness may compromise health and independent living. Hence, transfemoral amputees with low physical fitness should engage in regular physical activity to improve health, gait capacity, and independency