Lower extremity blood flow and responses to occlusion ischemia differ in exercise-trained and sedentary tetraplegic persons

OBJECTIVE: To test whether lower extremity blood flow and hyperemic responses to vascular occlusion differ among electrically stimulated exercise trained and sedentary tetraplegic persons and subjects without tetraplegia (control). DESIGN: Blinded cross-sectional comparison, control group. SETTING: Academic medical center. PARTICIPANTS: Ten sedentary tetraplegic men, 10 tetraplegic persons previously habituated to electrically stimulated cycling exercise for 0.4 to 7 years, and 10 nondisabled controls. OUTCOME MEASURES: Subjects underwent quantitative Doppler ultrasound examination of the common femoral artery (CFA). End-diastolic arterial images and arterial flow-velocity profiles obtained at rest and following five minutes of suprasystolic thigh occlusion were computer digitized for analysis of heart rate (HR), CFA peak systolic velocity (PSV), CFA cross-sectional area (CSA), flow velocity integral (FVI), and computed CFA inflow volume (IV). RESULTS: No group main effects were observed for resting HR or FVI. At rest, trained tetraplegic men had 14.9% greater PSV, 29.8% larger CSA, and 51.3% greater IV (p values < .05) than sedentary tetraplegic subjects. Resting PSV and IV of the trained subjects did not differ from controls, although CSA was smaller than controls (p < .05). Following occlusion, PSV, CSA, and IV averaged 16.5%, 33.4%, and 65.1% greater for trained tetraplegics persons, respectively, than sedentary tetraplegic subjects (p values < .05). Only CSA differed between the control and the trained groups (p < .05). CONCLUSION: Tetraplegic persons conditioned by electrically stimulated cycling have greater lower extremity blood flow and hyperemic responses to occlusion than do their sedentary counterparts.