Evidence of a limb- and shear stress stimulus profile dependent impact of high-intensity cycling training on flow-mediated dilation

Lower limb endurance training can improve conduit artery flow-mediated dilation (FMD) in response to transient increases in shear stress (reactive hyperemia; RH-FMD) in both the upper and lower limbs. Sustained increases in shear stress recruit a partially distinct transduction pathway and elicit a physiologically relevant FMD response (SS-FMD) that provides distinct information regarding endothelial function. However, the impact of training on SS-FMD is not well understood. The purpose of this study was to determine the impact of cycling training on handgrip exercise induced brachial artery(BA) FMD (BA SS-FMD) and calf plantar-flexion induced superficial femoral artery (SFA) FMD (SFA SS-FMD). RH-FMD was also assessed in both arteries. 28 young males were randomized to control (n=12) or training (n=16) groups. The training group cycled 30 min/day, 3 days/week for 4 weeks at 80% heart rate reserve. FMD was assessed in the BA and SFA pre- and post-intervention via Duplex ultrasound. Results are mean ±SD. Training did not impact SS-FMD in either artery, and SFA RH-FMD was also unchanged (p>0.05). When controlling for the shear rate stimulus via covariate analysis, BA RH-FMD improved in the training group (p=0.05)(Control: pre- 5.7±2.4%, post- 5.3±2.4%; Training: pre- 5.4±2.5%, post- 7.2±2.4%). Thus, endurance training resulted in non-uniform adaptations to endothelial function, with an isolated impact on the BA’s ability to transduce a transient increase in shear stress. • Training did not alter SS-FMD in the arm or leg. • RH-FMD was augmented in the arm only. • Thus training adaptations were limb and shear stress profile specific.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author