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 output at a given oxygen uptake. However, these issues have not been resolved fully. This study utilized lower-body positive pressure (LBPP) as an intervention during arm crank exercise in PARAS in order to examine this issue. Endurance-trained (TP, n = 7) and untrained PARAS (UP, n = 10) with complete lesions between T6 and T12, and a control group consisting 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 uptake (O2peak) remained unchanged for all groups following LBPP. LBPP resulted in a significant decrease in heart rate (HR) in UP and TP (P < 0.05), but not SAB subjects. LBPP produced an insignificant increase in cardiac output (Q) and stroke volume (SV). The significant decrease in HR in both PARA groups may indicate a modest hemodynamic benefit of LBPP at higher work rates where circulatory sufficiency may be most compromised. We conclude that PARAS possess a diminished cardiac output during exercise compared to the able-bodied, and LBPP fails to ameliorate significantly their exercise response irrespective of the conditioning level. These results support previous observations of a lower cardiac output during exercise in PARAS, but indicate that lower-limb blood pooling may not be a primary limitation to arm exercise in paraplegia.
The Toronto Hospital Centre for Cardiovascular Research, Charlie-Conacher Research Wing, Ontario, Canada.
R
R
Kaprielian
M J
MJ
Plyley
P
P
Klentrou
L S
LS
Goodman
J M
JM
Goodman
D000328:Adult; D002302:Cardiac Output / Q000502:physiology; D002320:Cardiovascular Physiological Phenomena; D015444:Exercise; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008150:Lower Body Negative Pressure; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010264:Paraplegia / Q000503:physiopathology*; D010806:Physical Education and Training; D010807:Physical Endurance; D012016:Reference Values; D013318:Stroke Volume / Q000502:physiology