Author(s): IIMURA, Y., OUE, A., Institution: TOYO UNIVERSITY, Country: JAPAN, Abstract-ID: 1104

INTRODUCTION:
Great venous capacitance refers to the large amount of blood contained in veins at rest. Venous return from the calf to the heart during leg exercise is increased by muscle pump (Folkow et al. 1970), which depends on the force of muscular contraction and the amount of blood in venous vessels (Barendsen and van den Berg 1984). Based on these factors, improved venous vascular properties (capacitance and compliance) at rest are expected to increase venous return during exercise, but this relationship has not yet been investigated. Therefore, the purpose of this study was to clarify the relationship between calf venous vascular properties at rest and calf venous return during leg exercise.
METHODS:
Twenty-two healthy young volunteers (15 men, 7 women; age, 22 ± 1 years; height, 166.3 ± 7.9 cm; weigh, 60.2 ± 11.8 kg; BMI, 21.6 ± 3.1 kg/m2) participated in this study. First, the change in calf volume in the supine position was measured using a cuff deflation protocol (Halliwill et al. 1999) by venous occlusion plethysmography in order to evaluate the capacitance and compliance in the calf veins at rest. Next, the participants rested in the supine position and then stood up and performed a tiptoe exercise. The change in calf volume was measured using strain-gauge plethysmography through this protocol. The change in calf volume during the postural change from supine to standing was calculated as the index of venous volume (VV), and the change in calf volume during the tiptoe exercise was assessed as the ejection volume (EV), which was used the index of venous return from the calf (Stewart et al. 2004).
RESULTS:
Calf venous capacitance at rest showed a significant positive correlation with VV (P = 0.027, r = 0.470), but not with EV (P = 0.793, r = -0.059). There was no significant correlation between calf venous compliance at rest and VV (P = 0.392, r = 0.192) or EV (P = 0.387, r = -0.194).
CONCLUSION:
These results suggest that the capacitance and compliance of calf veins at rest might not be correlated with calf venous return during leg exercise.

References
Barendsen and van den Berg, Angiology 35: 163-172, (1984).
Folkow et al., Acta Physiolo Scand 80: 61-72, (1970).
Halliwill et al., J Appl Physiol 87: 1555–1563, (1999).
Stewart et al., Am J physiol Heart Circ Physiol 286: H1216-H1222, (2004).
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