Influence of Vascular Function on VO2 Off-Kinetics

Abstract

0174 Excess post-exercise oxygen consumption (EPOC) has been attributed to metabolic, hemodynamic, neuroendocrine, and pulmonary factors. More recently, van Beekvelt et al. (Am J Physiol Heart Circ Physiol 280: H1741, 2001) reported a marked and prolonged post exercise hyperemia following intense exercise indicating an important role of the vasculature during the recovery phase. Interestingly, few studies have examined the Influence of venous function on EPOC. PURPOSE: To examine the relationship between measures of vascular function and EPOC. METHODS: Nondominant forearm in-flow, venous capacitance and outflow were examined in 15 individuals [age = 22±2.25y]. Forearm blood inflow was estimated at rest and following 5 min of upper arm occlusion (using a 240 mmHg occluding pressure). Forearm venous capacitance and outflow were obtained following 5 min of upper arm venous occlusion pressure at 7 mmHg below diastolic blood pressure. Participants underwent a symptom-limited upright incremental cycle ergometer test with gas exchange analysis and a 10-minute constant work rate protocol at 60% of VO2R. Recovery measurements were obtained with the participants seated on the ergometer for 10 minutes. RESULTS: Average VO2peak was 33.92±8.61 ml/kg/min (Range: 18.70 to 46.10 ml/kg/min). Recovery half-time (T1/2) for the submax test was 16.84±2.44 sec. Resting in-flow, reactive hyperemic flow response and venous outflow were 2.71±1.15, 19.15±4.25 and 37.07±10.86 ml/100ml/min, respectively. Venous capacitance was 2.11±0.82%. Bivariate correlations revealed significant associations between T1/2 and reactive hyperemic response (r = −0.68, p = 0.01) and T1/2 and venous outflow (r = −0.60, p = 0.02). Moreover, venous outflow responses were significantly correlated with reactive hyperemic responses (r = 0.54, p = 0.001) CONCLUSIONS: Reactive hyperemic blood flow response and venous outflow were significantly associated with recovery T1/2 following a 10-minute constant submaximal work rate protocol. These findings suggest an important role of both the arterial and venous circulations on EPOC.