THE EFFECT OF LOWER-BODY POSITIVE PRESSURE ON THE CARDIOVASCULAR-RESPONSE TO EXERCISE IN SEDENTARY AND ENDURANCE-TRAINED PERSONS WITH PARAPLEGIA

Exercise intolerance in persons with paraplegia (PARAS) is thought to be secondary to insufficient venous return and a subnormal cardiac out put at a given oxygen uptake. However, these issues have not been reso lved fully. This study utilized lower-body positive pressure (LBPP) as an intervention during arm crank exercise in PARAS in order to examin e this issue. Endurance-trained (TP, n = 7) and untrained PARAS (UP, n = 10) with complete lesions between T6 and T12, and a control group c onsisting of sedentary able-bodied subjects (SAB, n = 10) were tested. UP and TP subjects demonstrated a diminished cardiac output (via CO2 rebreathing) during exercise compared to SAB subjects. Peak oxygen upt ake ((V) over peak O-2peak) remained unchanged for all groups followin g LBPP. LBPP resulted in a significant decrease in heart rate (HR) in UP and TP (P less than or equal to 0.05), but not SAB subjects. LBPP p roduced an insignificant increase in cardiac output ((Q) over dot) and stroke volume (SV). The significant decrease in HR ill both PAPA grou ps may indicate a modest hemodynamic benefit of LBPP at higher work ra tes where circulatory sufficiency may be most compromised. We conclude that PARAS possess a diminished cardiac output during exercise compar ed to the able-bodied, and LBPP fails to ameliorate significantly thei r exercise response irrespective of the conditioning level. These resu lts support previous observations of a lower cardiac output during exe rcise in PARAS, but indicate that lower-limb blood pooling may not be a primary limitation to arm exercise in paraplegia.