The impact of preconditioning exercise on the vascular response to an oral glucose challenge.

Exercise elicits direct benefits to insulin sensitivity but may also indirectly improve glucose uptake by hemodynamic conditioning of the vasculature. The purpose of this study was to examine the modifying effect of three different types of exercise on the vascular response to an oral glucose challenge. Twenty healthy adults (9 women, 11 men; 23±3 years old) completed a standard oral glucose tolerance test (OGTT) at rest, as well as 1.5 hours after moderate continuous cycling exercise (30 min; 65% V̇O2peak), high intensity interval cycling exercise (10×1 min at 90% heart rate peak), and lower-load higher-repetition resistance exercise (25-35 repetitions/set, 3 sets). Brachial and superficial femoral artery blood flow, conductance, and oscillatory shear index were measured throughout the OGTT. Regardless of rested state or exercise preconditioning, the OGTT induced reductions in brachial artery blood flow and conductance (p<0.001), and transient increases in brachial and superficial femoral artery oscillatory shear index and retrograde blood flow (p<0.01). Continuous cycling and resistance exercise were followed with a small degree of protection against prolonged periods of oscillatory flow. Our findings imply transient peripheral vasoconstriction and decreased limb blood flow during a standard OGTT, for which prior exercise was unable to prevent in healthy adults. NOVELTY BULLETS • We investigated the impact of continuous, interval, and resistance exercise on the hemodynamic response to an oral glucose tolerance test (OGTT). • Our findings suggest decreased upper-limb blood flow during an OGTT is not prevented by prior exercise in healthy adults.