Association of Venous Function and Post-Exercise Oxygen Consumption

Excess post-exercise oxygen consumption (EPOC) has been attributed to metabolic, hemodynamic, neuroendocrine, and pulmonary factors. Interestingly, few studies have examined the role of venous system on EPOC. The purpose of this study was to examine the relationship between measures of vascular function and EPOC. Measures of vascular function and VO2 recovery kinetics were examined in 20 individuals [age=22+2.41 yrs]. Nondominant forearm arterial inflow, venous capacitance and venous outflow were evaluated at rest and after 5 minutes of upper arm occlusion, using strain gauge plethysmography. VO2 recovery kinetics was assessed using gas exchange analysis following a six-minute constant work rate protocol at 60 percent of VO2peak (VO2@60%), on a cycle ergometer. The average VO2peak was 33.48±8.22 ml×kg-1×min-1 (Range: 18.7 to 46.1 ml×kg-1×min-1). Following the six-minute constant work rate protocol, recovery half-time (T1/2VO2) and Tau were 17.01±3.51 seconds and 54.45±11.28 seconds, respectively. Arterial resting inflow was 2.77±1.51 ml×100ml-1×min-1, reactive hyperemic blood flow was 17.72±3.65 ml×100ml-1×min-1, venous capacitance was 2.86±0.72 percent, and venous outflow was 34.19±10.03 ml×100ml-1×min-1. Bivariate correlations revealed significant inverse associations between T1/2VO2 and the reactive hyperemic response (r=-0.48, p=0.03) and T1/2VO2 and venous outflow post-occlusion (r=-0.50, p=0.02). In conclusion, these findings suggest an important role of both the arterial and venous circulation on EPOC.