Changes in carotid blood flow and electrocardiogram in humans during and after walking on a treadmill.
Blood flow velocity in the common carotid artery and the electrocardiogram were measured simultaneously by telemetry in seven male subjects during 20-min walking on a treadmill at an exercise intensity corresponding to a mean oxygen uptake of 26.0 (SD 2.9) ml.kg-1.min-1. The mean cardiac cycle was shortened from 0.814 (SD 0.103) s to 0.452 (SD 0.054) s during this exercise. Of this shortening, 73% was due to shortening of the diastolic period and 27% to shortening of the systolic period. In the relatively small shortening of the mean systolic period [from 0.377 (SD 0.043) s to 0.268 (SD 0.029) s], the isovolumetric contraction time was shortened by 56%. During exercise, the heart rate (fc) increased by 79.4% [from 74.3 (SD 9.3) beats.min-1 to 133.3 (SD 14.8) beats.min-1], and the peak blood velocity (S1) in the common carotid artery increased by 56.1% [from 0.82 (SD 0.10) m.s-1 to 1.28 (SD 0.11) m.s-1]. After exercise, the S1 decreased rapidly to the resting level. The fc decreased more slowly, still being higher than the initial resting level 5 min after exercise. The diastolic velocity wave and the end-diastolic foot decreased during exercise. The blood flow rate in the carotid artery increased transiently by 13.5% at the beginning of exercise [from 5.62 (SD 0.63) ml.s-1 to 6.38 (SD 0.85) ml.s-1] and by 26.5% at the end of the exercise period [from 5.62 (SD 0.63) ml.s-1 to 7.11 (SD 1.34) ml.s-1].(ABSTRACT TRUNCATED AT 250 WORDS)
He
J
J
Department of Physiology, School of Medicine, University of Tokushima, Japan.
Jiang
Z L
ZL
Tanaka
H
H
Ikehara
T
T
Takahashi
A
A
Yamaguchi
H
H
Miyamoto
H
H
Iritani
T
T
Kinouchi
Y
Y
D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D017536:Carotid Artery, Common / Q000502:physiology*; D004562:Electrocardiography; D015444:Exercise / Q000502:physiology; D005080:Exercise Test; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D013997:Time Factors; D016138:Walking / Q000502:physiology*