Maximal cardiac output during arm exercise in the sitting position after cervical spinal cord injury.

OBJECTIVE To determine and compare haemodynamic responses at maximal arm-crank (ACE) and wheelchair exercise (WCE) in individuals with cervical spinal cord injury and pair-matched able-bodied individuals. METHODS Nine male, motor-complete cervical spinal cord injured and 9 able-bodied individuals performed graded, maximal ACE and WCE. Cardiac output, heart rate, and stroke volume were determined at rest and at maximal exercise in cervical spinal cord injured individuals. In able-bodied individuals, measurements were performed at rest and at the maximal workload of the matched cervical spinal cord injured individuals. RESULTS In cervical spinal cord injured, maximal cardiac output (ACE 7.4 (standard deviation (SD) 1.6); WCE 7.3 (SD 2.1) l/min) and heart rate (ACE 101 (SD 22); WCE 103 (SD 27) bpm) increased significantly compared with rest (4.6 (SD 1.0) l/min; 65 (SD 12) bpm), while stroke volume (ACE 77 (SD 22); WCE 73 (SD 21) ml) did not differ from rest (73 (SD 20) ml). In able-bodied individuals, cardiac output (rest 4.8 (SD 1.4); ACE 10.7 (SD 1.8); WCE 10.3 (SD 2.2) l/min), heart rate (rest 68 (SD 10); ACE 103 (SD 27); WCE 109 (SD 27) bpm), and stroke volume (rest 70 (SD 10); ACE 105 (SD 20); WCE 96 (SD 17) ml) increased significantly compared with rest. Cardiac output and stroke volume were significantly lower in cervical spinal cord injured compared with able-bodied individuals at the same workloads. CONCLUSION Haemodynamic responses to maximal exercise were similar for both exercise modes in individuals with cervical spinal cord injury. The lower cardiac output in individuals with cervical spinal cord injury compared with able-bodied individuals at equivalent workloads reflects the inability of the circulatory system to increase stroke volume.