Thirty minutes of handgrip exercise potentiates flow-mediated dilatation in response to sustained and transient shear stress stimuli to a similar extent

摘要

Brief (30min) exposure of the brachial artery (BA) to a sustained elevation in shear stress has been shown to potentiate subsequent BA flow-mediated dilatation (FMD) in response to a transient shear stress stimulus [reactive hyperaemia (RH) FMD]. It is unknown whether matching the sustained shear stress exposure to a subsequent sustained shear stress stimulus for FMD [via handgrip exercise (SS-FMD)] might enhance the potentiation of FMD. The purpose of the study, therefore, was to assess the impact of a 30min handgrip exercise intervention-induced elevation in shear stress on subsequent BA SS-FMD versus RH-FMD. Nineteen healthy men (22 +/- 3years) preformed a 30min rhythmic handgrip exercise intervention on two experimental days. BA-FMD was assessed using either an RH or a 6min sustained shear stress stimulus created via handgrip exercise (order of visits counterbalanced) at three time points: pre-intervention and 10 and 60min post-intervention. The FMD was assessed using duplex ultrasound. Shear stress was estimated as shear rate (SR=BA blood velocity/BA diameter). Data are mean +/- SD. Both SS and RH-FMD increased from pre-intervention to 10min post-intervention [SS-FMD (6min average), from 0.11 +/- 0.05 to 0.16 +/- 0.08mm; P=0.008; Cohen's d = 0.66; and RH-FMD, from 0.25 +/- 0.1 to 0.32 +/- 0.11mm; P=0.013; Cohen's d = 0.68]. The magnitude of enhancement in RH and SS-FMD did not differ (change in RH versus SS-FMD pre- versus 10min post-intervention, P=0.344). These findings suggest that exposure to elevated shear stress via 30min of handgrip exercise potentiates subsequent FMD in response to sustained and transient elevations in shear stress to a similar extent.