Energy Expenditure of Below-Knee Amputees During Harness-Supported Treadmill Ambulation

Diana Hunter, Elizabeth Smith Cole, Julie M. Murray, Tinker D. Murray

Traditional rehabilitation of amputees is primarily aimed at strengthening remaining musculature necessary for prosthetic use and gait training. Available gait training time, however, is often limited by pain, residual limb skin tolerance, and the patient's cardiovascular endurance. Harness-supported treadmill ambulation is a rehabilitation technique being used by physical therapists to decrease an individual's body weight by a given percentage during exercise. This, theoretically, allows an amputee to ambulate on a prosthesis at a lower energy cost. The purpose of this study was to compare the energy expenditure of healthy below-knee amputee volunteers with healthy able-bodied volunteers during harness-supported treadmill ambulation in order to determine if energy conservation is achieved. Subjects were tested on a treadmill, walking at .67 m/sec (1.5 mph) and 1.34 m/sec (3.0 mph) during each of the following randomized harness-supported treadmill ambulation situations: full body weight, 20% body weight supported, and 40% body weight supported. During the last minute of each trial, rate of perceived exertion, heart rate, and standardized indirect calorimetry oxygen consumption (VO2, ml/kg/min) measures were collected. Caloric expenditure (kJ/min) was calculated using metabolic conversion equations. Peak heart rate, peak VO2, and peak kJ/min were measured after the conclusion of the last walking trial by taking each subject to volitional fatigue. Data were analyzed for each harness-supported treadmill ambulation situation and group using analysis of variance (ANOVA). The researchers identified significantly lower ratings of perceived exertion, heart rates, and VO2s for able-bodied subjects versus below-knee amputees for all trials. Both groups demonstrated significantly lower heart rates, VO2s, and kJ/min at 1.34 m/sec with 40% body weight supported. Additionally, significantly lower VO2s and kJ/min were found for able-bodied subjects versus below-knee amputees at 1.34 m/sec for 20% body weight supported. The results of this study provide preliminary justification for physical therapists to utilize harness-supported treadmill ambulation with amputees when energy expenditure savings would be advantageous.

J Orthop Sports Phys Ther. 1995;21(5):268-276.

Key Words: amputees, ambulation, energy expenditure

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