Vasoconstriction in active calf persists after discontinuation of combined exercise with high-intensity elbow flexion

The present study aimed to determine whether vasoconstriction in active calf occurring during combined exercise diminished or persisted when added low- and high-intensity elbow flexion exercise ceased and single leg exercise continued. Six active women (mean age, 21.2 years) participated in this study. During 10-min plantar flexion exercise at 10% of maximum voluntary contraction (MVC), elbow flexion exercise at 10% MVC was added over the 3rd and 4th min. Calf blood flow did not change significantly upon superimposition and cessation of this elbow flexion exercise. However, when elbow flexion exercise at 50% MVC was added during the 7th and 8th min, calf blood flow above the resting value (2.23 +/- 0.23 mL 100 mL-1 min-1) decreased significantly (P < 0.05) from 6.72 +/- 0.87 (6th min) to 5.14 +/- 1.36 mL 100 mL-1 min-1 after 2 min of combined exercise and was accompanied by a similar change in the non-exercising calf blood flow value. The vascular conductance of the exercising calf decreased significantly (P < 0.01) from 6.48 +/- 1.08 (6th min) to 3.11 +/- 1.27 mL 100 mL-1 min-1 mmHg-1 at the end of the 2nd min of combined plantar flexion exercise with elbow flexion exercise at 50% MVC. After elbow flexion exercise at 50% MVC was discontinued and plantar flexion exercise at 10% MVC alone was performed, the vascular conductance in the exercising calf remained significantly low for the next 2 min. These results indicate that the vasoconstriction induced by adding high-intensity arm exercise is persistent, suggesting a major contribution of metabo-receptor-mediated vasoconstriction rather than central command- and mechano-receptor-mediated vasoconstriction.