Respiro-circulatory responses to forearm and calf exercise performed simultaneously were compared with corresponding responses to forearm or calf exercise performed separately in 9 active women aged 21.1 yr on average. Handgrip exercise and plantar flexion were carried out for 60 s in a supine position at a frequency of 60 times·min^-1 and the load was adjusted to 1/3 MVC. Forearm blood flow (FBF) increased to 9.64±1.00 ml·100 ml^-1·min^-1 immediately after handgrip exercise, and calf blood flow (CBF) to 12.72±0.72 ml·100 ml^-1·min^-1 after plantar flexion. These increases in FBF and CBF were not significantly different from those after combined arm and leg exercise. Blood flow to inactive limbs showed no significant changes. Rises in systolic and diastolic blood pressure at the end of exercise were significantly higher after handgrip exercise than after plantar flexion. However, no significant difference was found in mean blood pressure among the three types of exercise. Vo₂ and HR in combined exercise were significantly higher than those during handgrip exercise, but no significant difference was found between combined exercise and plantar flexion.
Thus the present results indicated that the circulation to active limbs was not restricted when exercise was performed at 1/3 MVC, and that inhibitory summation shown in the central respiro-circulatory response to increased active muscle mass could occur without restriction of the peripheral circulation to the active muscle.