Reduced arterial diameter during static exercise in humans

In eight subjects luminal diameter of the resting limb radial and dorsalis pedis arteries was determined by high‐resolution ultrasound (20 MHz). This measurement was followed during rest and during 2 min of static handgrip or of one‐leg knee extension at 30% of maximal voluntary contraction of another limb. Static exercise increased heart rate and mean arterial pressure, which were largest during one‐leg knee extension. After exercise heart rate and mean arterial pressure returned to the resting level. No changes were recorded in arterial carbon dioxide tension, and the rate of perceived exertion was ˜ 15 units after both types of exercise. The dorsalis pedis arterial diameter was 1.50±0.20 mm (mean and SE) and the radial AD 2.45±0.12 mm. During both types of contractions the luminal diameters decreased ˜ 3.5% within the first 30 s (P< 0.05), and during one‐leg knee extension they continued to decrease to a final exercise value 7.6±1.1% lower than at rest (P < 0.05). Thus, they became smaller than during the handgrip. After exercise resting values were reestablished. When the arterial diameter was expressed in relation to mean arterial pressure for the radial and dorsalis pedis artery was 22±3 and 28±3% lower during handgrip than the relation during rest, respectively. After one‐leg knee extension both arteries reached 30±4% lower values. This study demonstrated arterial constriction in the resting limbs within the first 30 s of static exercise, and continued constriction during one‐leg knee extension. These results support to the hypothesis that central command and/or muscle mechano‐ receptors influence arterial tone, and that the exercise pressor reflex becomes important with the involvement of a large muscle mass.