Cardiac output in paraplegic subjects at high exercise intensities

Summary The purpose of this investigation was to compare cardiac output ( _c ) in paraplegic subjects (P) with wheelchair-confined control subjects (C) at high intensities of arm exercise. At low and moderate exercise intensity _c was the same at a given oxygen uptake ( O₂) in P and C. A group of 11 athletic male P with complete spinal-cord lesions between 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 O₂ ( O_2max) was significantly lower, O_2max per kilogram body mass was equal and maximal heart rate (f _c) was significantly higher in P compared to C. At O₂ of 1.3, 1.5 and 1.7 1-min^–1, and for P 65%–90% of the O_2max, _c was not significantly different between the groups, although, _c in P was achieved with a significantly lower stroke volume (SV) and a significantly higherf _c. Although the SV was lower in P, it 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 _c at a given O₂ in both groups indicated that, even at high exercise intensities, circulation in P can be considered isokinetic with a complete compensation byf _c for a lower SV.