CARDIAC-OUTPUT IN PARAPLEGIC SUBJECTS AT HIGH EXERCISE INTENSITIES

The purpose of this investigation was to compare cardiac output (Q(c)) in paraplegic subjects (P) with wheelchair-confined control subjects (C) at high intensities of arm exercise. At low and moderate exercise intensity Q(c) was the same at a given oxygen uptake (VO2) in P and C. A group of 11 athletic male P with complete spinal-cord lesions betwe en T6 and T12 and a group of 5 well-matched athletic male C performed maximal arm-cranking exercise and submaximal exercise at 50%, 70% and 80% of each individual's maximal power output (W(max)). Maximal VO2 (V O2max) was significantly lower, VO2max per kilogram body mass was equa l and maximal heart rate (f(c)) was significantly higher in P compared to C. At VO2 Of 1.3, 1.5 and 1.7 l . min-1, and for P 65%-90% of the VO2max, Q(c) was not significantly different between the groups, altho ugh, Q(c) in P was achieved with a significantly lower stroke volume ( SV) and a significantly higher f(c). Although the SV was lower in P, i t followed the same pattern as SV in C during incremental exercise, i. e. an increase in SV until about 45% W(max) and thereafter a stable SV . The similar Q(c) at a given VO2 in both groups indicated that, even at high exercise intensities, circulation in P can be considered isoki netic with a complete compensation by f(c) for a lower SV.