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

Abstract

Brief (30 min) 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 30 min handgrip exercise intervention-induced elevation in shear stress on subsequent BA SS-FMD versus RH-FMD. Nineteen healthy men (22 ± 3 years) preformed a 30 min rhythmic handgrip exercise intervention on two experimental days. BA-FMD was assessed using either an RH or a 6 min sustained shear stress stimulus created via handgrip exercise (order of visits counterbalanced) at three time points: pre-intervention and 10 and 60 min 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 10 min post-intervention [SS-FMD (6 min average), from 0.11 ± 0.05 to 0.16 ± 0.08 mm; P = 0.008; Cohen's d = 0.66; and RH-FMD, from 0.25 ± 0.1 to 0.32 ± 0.11 mm; 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 10 min post-intervention, P = 0.344). These findings suggest that exposure to elevated shear stress via 30 min of handgrip exercise potentiates subsequent FMD in response to sustained and transient elevations in shear stress to a similar extent.

Exercise-induced vasodilation is not impaired following radial artery catheterization in coronary artery disease patients

“…shear stress mediated (1,18,32). For example, McPhee and Pyke (18) suggested that handgrip exercise resulted in similar vasodilation-induced by reactive hyperemia (FMD) and sustained shear (HE).…”

“…shear stress mediated (1,18,32). For example, McPhee and Pyke (18) suggested that handgrip exercise resulted in similar vasodilation-induced by reactive hyperemia (FMD) and sustained shear (HE). In contrast, there are other studies suggesting that vasodilation in response to reactive and active hyperemia may be driven by distinct mechanisms (25).…”

The passive leg movement technique for assessing vascular function: the impact of baseline blood flow

“…Basal leg blood flow can be affected by numerous common stimuli including exercise, mental stress, arousal and a variety of environmental factors (McPhee & Pyke, 2018; Pearson et al., 2011; Sarabi & Lind, 2001; Tinken et al., 2009; Venturelli et al., 2012). In this investigation, cutaneous heating was employed as a means of experimentally manipulating baseline blood flow prior to the assessment of PLM‐induced hyperaemia.…”

“…As shear stress is a primary stimulus in the PLM blood flow response, the magnitude of baseline blood flow may play an important role in the subsequent stimulus response. Of note, baseline leg blood flow, and therefore shear stress, can be affected by many common conditions, including prior exercise, level of arousal and numerous environmental factors (McPhee & Pyke, 2018; Pearson et al., 2011; Tinken et al., 2009; Venturelli et al., 2012). However, studies aiming to pre‐expose the vasculature to increased shear stress, in order to examine the effect on NO‐mediated vasodilation, have produced conflicting results (Doshi et al., 2001; Green et al., 2014; Joannides et al., 1995; Kooijman et al., 2008; Sarabi & Lind, 2001).…”

“…However, studies aiming to pre‐expose the vasculature to increased shear stress, in order to examine the effect on NO‐mediated vasodilation, have produced conflicting results (Doshi et al., 2001; Green et al., 2014; Joannides et al., 1995; Kooijman et al., 2008; Sarabi & Lind, 2001). For instance, endothelium‐dependent vasodilation in the forearm, elicited by the infusion of methacholine, has been documented to be diminished after mental stress‐induced hyperaemia, indicative of attenuated NO synthesis (Sarabi & Lind, 2001), while, in contrast, an increase in brachial artery shear stress, facilitated by handgrip exercise or forearm heating, augmented flow‐mediated dilatation (FMD), implying enhanced endothelium‐dependent vasodilation (McPhee & Pyke, 2018; Tinken et al., 2009). Regardless, the impact of increased baseline CFA blood flow, or elevated shear stress, on the PLM response is unknown.…”