Graded exercise to exhaustion reduced the carotid pulsatile pressure:diameter ratio from 27.3 to 13.7 microm mmHg(-1) during exercise, followed by an increase to 33.9 at 60 minutes post-exercise.
Observational (n=10)
Does strenuous exercise alter carotid artery diameter and pulsatile pressure:diameter ratio in young healthy subjects?
Strenuous exercise induces dynamic changes in carotid artery diameter and distensibility that closely correlate with post-exercise baroreflex sensitivity, highlighting the role of mechanical factors in baroreflex control.
Absolute Event Rate: 13.7% vs 27.3%
Arterial baroreflex function is altered by dynamic exercise, but it is not clear to what extent baroreflex changes are due to altered transduction of pressure into deformation of the barosensory vessel wall. In this study we measured changes in mean common carotid artery diameter and the pulsatile pressure : diameter ratio (PDR) during and after dynamic exercise. Ten young, healthy subjects performed a graded exercise protocol to exhaustion on a bicycle ergometer. Carotid dimensions were measured with an ultrasound wall-tracking system; central arterial pressure was measured with the use of radial tonometry and the generalized transfer function; baroreflex sensitivity (BRS) was assessed in the post-exercise period by spectral analysis and the sequence method. Data are given as means +/- S.E.M. Mean carotid artery diameter increased during exercise as compared with control levels, but carotid distension amplitude did not change. PDR was reduced from 27.3+/-2.7 to 13.7+/-1.0 microm mmHg(-1). Immediately after stopping exercise, the carotid artery constricted and PDR remained reduced. At 60 min post-exercise, the carotid artery dilated and the PDR increased above control levels (33.9+/-1.4 microm mmHg(-1)). The post-exercise changes in PDR were closely paralleled by those in BRS (0.74< or = r < or =0.83, P<0.05). These changes in mean carotid diameter and PDR suggest that the mean baroreceptor activity level increases during exercise, with reduced dynamic sensitivity; at the end of exercise baroreceptors are suddenly unloaded, then at 1 h post-exercise, baroreceptor activity increases again with increasing dynamic sensitivity. The close correlation between PDR and BRS observed at post-exercise underlies the significance of mechanical factors in arterial baroreflex control.
Studinger et al. (Tue,) conducted a observational in Healthy (n=10). Graded exercise protocol to exhaustion vs. Resting control levels was evaluated on Pulsatile pressure : diameter ratio (PDR). Graded exercise to exhaustion reduced the carotid pulsatile pressure:diameter ratio from 27.3 to 13.7 microm mmHg(-1) during exercise, followed by an increase to 33.9 at 60 minutes post-exercise.