In this study the regulation of vascular tone inducing the blood flow increase at the onset of exercise is examined. Therefore, our calf circulation model was extended with a regulation model to simulate changes in vascular tone depending on myogenic, metabolic and baroreflex regulation. The simulated blood flow corresponded to the in vivo response and it was concluded that metabolic activation caused the flow increase shortly after muscle contraction. Secondly, the change in baseline flow upon tilt was a result of myogenic and baroreflex activation. Based on a sensitivity analysis the myogenic gain was identified as most important parameter.