Assessment of aerobic capacity and walking economy of unilateral 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 VO2maxmay be systematically underestimated, and the validity of these test protocols is questionable.Objectives:(1) Investigate validity and reliability of a VO2maxwalking protocol and (2) compare the VO2maxof a transfemoral amputee group with a group of matching controls.Study design:(1) Randomized crossover study: walking versus running VO2maxfor the control group and (2) case-control study: transfemoral amputees versus control group VO2max.Methods:Twelve transfemoral amputees and control participants performed a walking VO2maxtest with increasing treadmill inclinations to voluntary exhaustion. The control group also completed a running (“gold-standard”) VO2maxtest.Results:Mean (standard deviation) control group VO2maxfollowing walking and running was similar, that is, 2.99 (0.6) L min−1and 3.09 (0.7) L min−1, respectively. Mean (standard deviation) transfemoral amputee walking VO2maxwas 2.14 (0.8) L min−1(compared to CON; p < 0.01). Mean intraclass correlation coefficient of repeated VO2measurements was 0.97, and within-subjects standard deviation was 60 mL min−1.Conclusions:The walk protocol is valid. Walking VO2maxof transfemoral amputees was 40% lower compared to control group. Reliability of the walking protocol is comparable to other walking protocols.Clinical relevanceThe 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.