The effect of posture and fitness level on posterior tibial artery size
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ARTERIAL DIAMETER has been shown to change in response to both acute and chronic stimuli. Exercise has been shown to result in a chronically elevated artery diameter, and chronic inactivity results in decreased artery size. Arterial range is a measure of the operating diameter in an artery, from minimum to maximum. Because it is unclear how arterial range changes as a result of exercise and posture, the purpose of this study was to examine the effect of supine and seated posture on arterial range in the posterior tibial artery in endurance-trained and untrained sedentary subjects. We examined arterial range in the posterior tibial artery in a supine and seated posture for each subject using Doppler ultrasound. We hypothesized that the seated posture would result in decreased arterial range in both endurance-trained and sedentary subjects, and that endurance training would increase arterial diameter and range. It was further hypothesized that an interaction between posture and endurance training would be present. Arterial range, VO2peak, and fat-free mass from DXA were measured in 21 subjects. The mean VO2peak for the endurance-trained and untrained group was 65.37 ± 8.41and 38.71 ± 8.00, respectively. Arterial diameter was similar between groups. Arterial range decreased by 21.5% from the supine to seated posture (p<0.01), but there was no significant effect of training status. In addition, the seated posture resulted in a 53.2% increase in resting arterial constriction (p<0.01), while there was no significant effect of training status. This was mainly due to an 8.1% increase in minimum diameter from the supine to seated posture (p<0.01). Arterial range was significantly decreased in the seated versus supine posture. In addition, we were unable to detect a significant influence of chronic endurance training on sympathetic tone or structural remodeling in the posterior tibial artery.