Transient increase in femoral arterial blood flow to the contralateral non-exercising limb during one-legged exercise

We studied the effect of exercise intensity and duration on blood flow to the non-exercising leg during one-legged dynamic knee extension. Femoral arterial blood flow (FBF) to the non-exercising leg, blood pressure (BP), and heart rate (HR) were monitored during one-legged dynamic knee extension exercise at 15, 30, and 45% maximal voluntary contraction (MVC) in seven healthy females. There was an interaction between exercise intensity and duration for FBF and FVC (P < 0.01). During the initial phase of contralateral leg exercise at all intensities, FBF and femoral vascular conductance (FVC) of non-exercising leg increased, and the increase was larger at higher intensities (P < 0.01). After initial vasodilatation, FBF and FVC decreased to baseline, which suggests the vasoconstriction. However, FBF and FVC gradually increased during exercise at 15% MVC. We conclude that transient vasodilatation at the onset of exercise is followed by gradual change to vasoconstriction in non-exercising limb during dynamic one-legged exercise and these changes are exercise intensity- and duration-dependent.