Effects of interval versus continuous exercise on cerebral vascular flow‐mediated dilatation in young healthy males

Abstract

Aerobic exercise reduces the risk of cerebrovascular dysfunction. One proposed mechanism is exercise‐induced increases in cerebral shear stress (SS) improving cerebral endothelial function. A recent report indicated that interval exercise (Int‐Ex) induces greater cerebral SS than continuous exercise (Con‐Ex); however, its effect on cerebral endothelial function remains unclear. We hypothesized that Int‐Ex would enhance cerebral SS and, consequently, cerebral endothelial function more than Con‐Ex. Fourteen healthy males (21 ± 0.6 years) completed 32 min of Int‐Ex and work‐equivalent Con‐Ex on a semi‐recumbent bike on separate days. Cerebrovascular flow‐mediated dilatation (cFMD) was assessed before exercise (Pre), 15 min (Post‐15) and 40 min post‐exercise (Post‐40). cFMD was defined as peak internal carotid artery vasodilatation (Δ% from baseline; Duplex ultrasound) in response to a 30‐s hypercapnic exposure, raising end‐tidal partial pressure of carbon dioxide by ~7 mmHg. Post‐exercise cerebral SS was greater after Int‐Ex versus Con‐Ex (p = 0.002). Int‐Ex evoked a ~37% increase in post‐exercise cerebral SS compared to rest, with a negligible increase for Con‐Ex. cFMD did not differ between Int‐Ex and Con‐Ex trials before exercise (Pre, 6.35 ± 3.89% vs. 5.54 ± 3.83%; p = 0.542) and remained unchanged post‐exercise (Post‐15, 7.20 ± 4.47% vs. 6.13 ± 4.08%; Post‐40, 5.69 ± 3.86% vs. 6.94 ± 3.55%; p = 0.583). These results indicate that Int‐Ex and Con‐Ex have similar acute effects on cerebral endothelial function.