Study design: A paired comparison of the peak and submaximal responses of oxygen uptake and heart rate in patients with spinal cord injury (SCI) performing voluntary arm cycle exercise and functional electrical stimulation (FES) leg cycling exercise. Objectives: To test if the blunted heart rate response and slower rate of adjustment of oxygen uptake seen in patients with SCI performing FES leg cycle exercise are also characteristic of arm exercise in these patients. Methods: Eight paraplegics performed incremental and constant work rate (CWR) exercise with the legs and arms. Mean response times (MRT) for Vo 2 during exercise (on) and in recovery (o ) were calculated from the breath-by-breath Vo 2 pro®le. Results: Peak heart rate was higher during incremental arm exercise, and uncorrelated with that observed during incremental FES leg cycling. For the same increase in Vo 2 , constant work rate arm exercise was associated with faster (and normal) Vo 2 kinetics, greater increase in heart rate, and lower end-exercise blood lactate, compared to FES leg cycling. Conclusions: The consistently higher peak heart rate and Vo 2 , and faster Vo 2 kinetics, for voluntary arm compared to FES leg cycle exercise suggest no intrinsic dysfunction of heart rate control in these paraplegics. Rather, these data suggest that during FES leg cycling the changes seen are due to some characteristic speci®c to the injury, such as reduced muscle mass and/or deconditioning of the remaining muscle.

AimsTo examine the influence of a negative hydrostatic column via ‐6° head‐down tilt (HDT) exercise on cardiovascular performance and to determine if the HDT posture stimulates greater cardiovascular adaptations during exercise training compared to upright (UPR).Methods9 males (21±2 yrs) performed VO2peak cycle exercise tests in the UPR, supine (SUP), and HDT positions. 9 different males (20±2 yrs) were endurance trained on a cycle ergometer in the UPR position for 8 wks (UPRTN) or in the UPR position for 4 wks followed by 4 wks in the HDT position (HDTTN).ResultsDuring acute exercise, VO2peak was decreased in the SUP and HDT positions compared to the UPR (2.01±0.46, 2.01±0.51 vs. 2.32±0.61 L/min respectively, P < 0.05). Stroke volume (SV) at 100 watts was greater in the HDT position compared to the UPR (77±5 vs 71±4 ml/beat, P < 0.05). Following training SV at 100 watts increased from 77±1 to 85±9 ml/beat in the HDTTN group during UPR exercise (P < 0.05). In addition, SV increased from 76±10 to 85±16 ml/beat in the HDT position for the same individuals (P < 0.05). SV in the UPRTN during 100 watts in the HDT position was unchanged but increased during UPR exercise following 8wks of training (65±3 to 75±5 ml/beat, P = 0.21).ConclusionsHDT exercise increases sub‐maximal SV compared to UPR exercise. Training in the HDT position induces cardiovascular adaptations in both UPR and HDT exercise that are not achieved with UPR training.

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