ARTERIAL DIAMETER AND MEAN BLOOD VELOCITY MEASUREMENTS

Abstract

The purpose of this study was to determine: 1) inter-observer difference in arterial diameter (AD) measures; 2) femoral AD changes during exercise; and 3) variability of mean blood velocity (MBV) measurements. Seven subjects (23 ± 2 yr) performed 4–6 repeats on different days of constant-load single-leg knee extension exercise transitions from unloaded exercise to a work rate eliciting 80% of VO2 peak, followed by loadless recovery. Doppler ultrasound was used to image the femoral artery during one trial for each subject, and to measure MBV on each trial. AD measurements were made independently by two investigators at rest and every 2 min throughout the test. MBV data were averaged over 2 s intervals (1 contraction cycle) and 10 s averages were taken during the first and last min of each phase of the trial to test for day-to-day variability. Mean AD measurements across all subjects and conditions were highly correlated (r = 0.93, r2 = 0.86) and were not significantly different between the two observers (8.2 ± 1.0 mm vs 8.4 ± 1.2 mm, mean ± SD). AD did not change significantly from rest values at any time point. The coefficient of variation (CV) for MBV day-to-day variability at any one time point ranged from 7.1 to 38.5% and the mean CV across all subjects and time points was 20.7%. Variability was largest during unloaded exercise, but similar during heavy exercise and recovery. These data demonstrate that femoral artery diameter does not change significantly from rest through to heavy exercise and any rest-exercise difference is similar in magnitude to that of inter-observer differences. Furthermore, because of the variability in femoral artery MBV, we recommend the use of repeated trials to obtain an accurate MBV. Supported in part by NSERC, Canada