Aerobic training and vascular protection: Insight from altered blood flow patterns.

Acute alteration of blood flow patterns can substantially reduce blood vessel function and, if consistently repeated, may chronically reduce vascular health. Aerobic exercise training is associated with improved vascular health, but it is not well understood whether aerobic training-induced vascular adaptations provide protection against acute vascular insults. This study sought to determine whether prior upper limb aerobic training can attenuate the vascular dysfunction resulting from an acute vascular insult (increased retrograde/oscillatory shear). Ten young arm-trained (AT) men (rowers; 22 ± 1 years of age) and 10 untrained (UT) male control subjects (21 ± 3 years of age) were recruited for this study. Subjects completed two brachial artery (BA) flow-mediated dilatation (FMD) tests separated by an acute bout of subdiastolic cuff inflation (SDCI) of the distal forearm. Brachial artery dilatation (normalized for the shear stimulus) and reactive hyperaemia evaluated during the BA FMD test were used to determine conduit artery and microvascular function, respectively. Data were presented as mean values ± SD. The AT group reported significantly greater whole body (peak oxygen uptake; P = 0.01) and forearm aerobic capacity (P < 0.001). The SDCI intervention significantly increased retrograde (P < 0.001) and oscillatory shear (P < 0.001) in both groups. After the SDCI, microvascular function (post-cuff release hyperaemia), but not conduit artery function (shear-induced BA dilatation), was significantly reduced from pre-SDCI values (P = 0.001) independent of group. This study revealed that young men with prior upper limb aerobic training, when compared with untrained control subjects, were equally susceptible to the microvascular dysfunction associated with an acute increase in retrograde/oscillatory shear.