Energy cost of paraplegic locomotion using the ParaWalker--electrical stimulation "hybrid" orthosis.

In an adult paraplegic walking with the ParaWalker, electrical stimulation of the stance-side gluteal muscles (gluteus maximus and medius) reduces the force applied through the crutches during the gait cycle. In this study, five posttrauma, fully rehabilitated, complete paraplegic adult men walked using their ParaWalkers both without and with electrical stimulation augmentation. Oxygen consumption and distance covered during the test period were monitored to derive speed (m s-1), energy cost (J kg-1 m-1), and energy consumption (J kg-1 s-1). With the ParaWalker-electrical stimulation "hybrid" orthosis, three subjects increased their walking speed (10.92%, 7.85%, and 9.27%) and two reduced it (4.49% and 9.36%). Energy cost was reduced in four subjects (6.47%, 7.93%, 6.92%, and 7.97%) but remained the same for the fifth. Energy consumption was reduced in four subjects (0.82%, 11.06%, 0.38%, and 10.28%) and increased in one subject (4.19%). Results were better than those in a previous study of paraplegic locomotion using functional electrical stimulation and long-leg braces. Although electrical stimulation augmentation yields only a small reduction in energy cost, its long-term physiologic effect could be significant in increasing the aerobic-anaerobic threshold of an individual via recruitment of large muscles like the gluteus maximus and medius, thereby increasing performance in a sustained activity like walking.