In-exercise vascular shear rate during acute continuous and interval exercise: impact on endothelial function and miR-21

Abstract

Endothelial cell phenotype and endothelial function are regulated by hemodynamic forces, particularly wall shear stress (WSS). During a single bout of exercise, the specific exercise protocol can affect in-exercise WSS patterns and, consequently, endothelial function. MicroRNAs might provide a biomarker of in-exercise WSS pattern to indicate whether a specific exercise bout will have a positive effect on endothelial function. We evaluated the effect of acute interval (IT) and continuous (CON) in-exercise WSS patterns upon postexercise endothelial function and circulating microRNA (miR)-21 expression. Methods and results: 13 participants performed CON and 3 different IT exercise protocols matched for duration and intensity on separate days. Oxygen uptake, heart rate, and brachial artery blood flow were recorded throughout the exercise. Brachial artery flow-mediated dilation (FMD) was performed pre-exercise and 15 min postexercise. Plasma samples were acquired pre-exercise and 6 h postexercise to determine miR-21 expression. In-exercise shear rate (SR) patterns (a surrogate of WSS) differed according to the CON or IT work-rate profile. In-exercise anterograde SR was greater in CON than IT exercise ( P < 0.05), but retrograde SR was equivalent between exercise protocols ( P > 0.05). Oscillatory shear index was higher during IT versus CON exercise ( P < 0.05). Postexercise FMD increased (pre: 7.08% ± 2.95%, post: 10.54% ± 4.24%, P < 0.05), whereas miR-21 expression was unchanged (pre: 12.0% ± 20.7% cel-miR-39, post: 11.1 ± 19.3% cel-miR-39, P > 0.05) with no effect of exercise protocol ( P > 0.05). Conclusions: CON and IT exercise induced different SR patterns but equivalent improvements in acute endothelial function. The absence of change in miR-21 expression suggests that miR-21 is not a suitable biomarker of exercise-induced SR. NEW & NOTEWORTHY Interval exercise has the potential to negatively impact vascular adaptations because of repeated oscillations in vascular shear. To our knowledge, we are the first to continuously assess exercise-induced shear throughout different acute exercise protocols and examine its relationship with acute endothelial function and a circulating biomarker of shear (miR-21). These experiments provide clear data indicating enhancement of the acute vascular response from differing interval exercise protocols, with the study also providing detailed vascular and shear responses for future reference.

Greater increase in internal carotid artery shear rate during aerobic interval compared to continuous exercise in healthy adult men

“…It is noteworthy that blood velocity and shear rate (SR) associated with the flow pattern contribute to endothelial function (Chatzizisis et al, 2007;Thijssen et al, 2009), which can be independently modified as a function of the exercise mode. As per a recent study (Lyall et al, 2019), aerobic interval exercise can cause a different pattern of SR in the systemic vasculature as compared to an equivalent work volume of aerobic continuous exercise; interval exercise caused a greater increase in the oscillatory SR as compared to continuous exercise. However, to our knowledge, no study has examined the impact of interval exercise, especially with respect to blood velocity and SR profile, on the cerebral vasculature.…”

“…Further, exercise‐induced increases in flow‐mediated dilation (FMD) in the systemic vasculature, as an index of endothelial function, were deemed not different between the exercise protocols (Lyall et al, 2019). It is noteworthy that exercise increases the retrograde SR in the systemic vasculature (Lyall et al, 2019); however, retrograde SR is absent in the cerebral vasculature (Rodrigues et al, 2020). In fact, in this present study, the reversal of the ICA blood flow was absent even with the higher workloads during aerobic Interval‐Ex.…”

“…The bar and lines represent group average and individual values. * (Lyall et al, 2019). It is noteworthy that exercise increases the retrograde SR in the systemic vasculature (Lyall et al, 2019); however, retrograde SR is absent in the cerebral vasculature (Rodrigues et al, 2020).…”

“…* (Lyall et al, 2019). It is noteworthy that exercise increases the retrograde SR in the systemic vasculature (Lyall et al, 2019); however, retrograde SR is absent in the cerebral vasculature (Rodrigues et al, 2020). In fact, in this present study, the reversal of the ICA blood flow was absent even with the higher workloads during aerobic Interval-Ex.…”

“…In the systemic vasculature, although exercise‐induced increases in antegrade SR are greater during continuous exercise than during interval exercise, the ratio of retrograde SR to total SR (i.e., oscillatory shear index) is higher during interval exercise than during continuous exercise (Lyall et al, 2019), indicating that the effect of retrograde SR on the mean SR may be higher during interval exercise. Retrograde SR has a harmful effect on the endothelial function (Simmons et al, 2011; Thijssen et al, 2009).…”