LIMITS TO MAXIMAL PERFORMANCE IN INDIVIDUALS WITH SPINAL-CORD INJURY

The purpose of this study was to examine the effect of four conditions that might improve oxygen transport and/or utilization during maximal exercise performance in individuals with spinal cord injury (SCI). Fi ve males with tetraplegia (TP) and four males with paraplegia (PR) per formed maximal arm cranking exercise in the following positions: 1) si tting 2) supine; and 3) sitting with the addition of a) anti-gravity s uit (anit-G), b) elastic stockings and abdominal binder, and c) functi onal electrical stimulation (FES) of the paralysed leg muscles. Peak p ower output (PO peak), peak oxygen uptake ((V) over dot O(2)peak), pea k heart rate (HR peak) and maximal systolic blood pressure were signif icantly lower in TP compared to PR for all conditions. A significant d ecrease in HR peak for PR, and a significant increase in (V) over dot O(2)peak/kg for TP was seen during the supine compared to sitting cond ition. Respiratory exchange ratio (R) decreased significantly during t he FES compared to the sitting condition in TP. No other changes were observed for any of the other conditions in either group. Improvements in central circulation previously reported during submaximal exercise for these four conditions did not result in a concomitant rise in max imal exercise performance. The results of this study suggest that the limitation in (V) over dot O(2)peak for individuals with SCI is locate d peripherally (small active muscle mass) rather than centrally (heart or lungs).