RELATIONSHIPS OF OXYGEN-UPTAKE, HEART-RATE, AND RATINGS OF PERCEIVED EXERTION IN PERSONS WITH PARAPLEGIA DURING FUNCTIONAL NEUROMUSCULAR STIMULATION ASSISTED AMBULATION

Previous reports have described significant limitations in the daily u se of functional neuromuscular stimulation (FNS) ambulation systems by persons with spinal cord injuries (SCI). The potential application of these devices to provide physiological benefits as an exercise modali ty has prompted a reconsideration of the technology. However, the acut e physiological effects related to the use of FNS systems have not bee n thoroughly examined. The purpose of this study was to investigate th e relationships of oxygen consumpation (VO2), heart rate (HR), and rat ings of perceived exertion (RPE) during FNS ambulation by persons with SCI paraplegia. Eleven persons with thoracic level paraplegia, aged 2 1.5 to 38.0 years, participated in an incremental FNS ambulation test. Metabolic measures were collected continuously via open circuit spiro metry as the subjects performed a series of ambulation passes of progr essively increasing pace. At the end of each ambulation pass, HR and R PE measures were collected. The test was terminated when either the su bjects judged the effort to be maximal or when the investigators deeme d the effort to be maximal based on HR. A strong linear relationship w as documented between the VO2 and HR measures of all subjects througho ut subpeak levels of FNS ambulation. RPE did not vary proportionally w ith VO2 until relatively high levels of exercise intensity were reache d. This study indicates that HR, but not RPE, is an appropriate indica tor of exercise intensity for persons with SCI paraplegia using a FNS ambulation system.