The vascular waterfall theory attributes decreased muscle perfusion during contraction to increased intramuscular pressure (P_IM ) and concomitant increase in venous resistance. Although P_IM is distributed during contractions, this theory does not account for heterogeneity.This study hypothesises that pressure heterogeneity could affect the interaction between P_IM rise and perfusion. Regional tissue perfusion during submaximum (100 kPa) tetanic contraction is studied, using a finite element model of perfused contracting skeletal muscle. Capillary flow in muscles with one proximal artery and vein (SIM1) and with an additional distal arteryand vein (SIM2) is compared.Blood flow and pressures at rest and P_IM during contraction (25 kPa maximally) are similar betweensimulations, but capillary flow and venous pressure diffe! r.In SIM2, venous pressure and capillary flow correspond to P_IM distribution, whereas capillary flow in SIM1 is less than 10% of flow in SIM2, in the muscle half without draining vein.This difference is caused by a high central P_IM, followed by central venous pressure rise, in agreement with the waterfall theory. The high central pressure (SIM1) obstructs outflow from the distal veins. Distal venous pressure rises until central blood pressure is reached, although local P_IM is low. Adding a distal vein (SIM2)restores the perfusion. It is concluded that regional effects contribute to the interaction between P_IM and perfusion during contraction. Unlike stated by the vascular waterfall theory, venous pressure may locally exceed P_IM. Although this can be explained by the principles of this theory, the theory does not include this phenomenon as such.