Remote ischemic preconditioning prevents reduction in brachial artery flow-mediated dilation after strenuous exercise

• Published in: American journal of physiology. Heart and circulatory physiology 2012-09, Vol.303 (5), p.H533-H538
• Main Authors: Bailey, Tom G, Birk, Gurpreet K, Cable, N Timothy, Atkinson, Greg, Green, Daniel J, Jones, Helen, Thijssen, Dick H J
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological; Adult; Blood Flow Velocity; Brachial Artery - diagnostic imaging; Brachial Artery - physiopathology; Circulatory system; Clinical trials; Cross-Over Studies; Endothelium, Vascular - diagnostic imaging; Endothelium, Vascular - physiopathology; England; Exercise; Exercise Test; Heart; Humans; Ischemic Preconditioning - methods; Lower Extremity - blood supply; Male; Mens health; Regional Blood Flow; Running; Single-Blind Method; Time Factors; Tourniquets; Ultrasonography, Doppler; Vasodilation; Young Adult
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.00272.2012

Strenuous exercise is associated with an immediate decrease in endothelial function. Repeated bouts of ischemia followed by reperfusion, known as remote ischemic preconditioning (RIPC), is able to protect the endothelium against ischemia-induced injury beyond the ischemic area. We examined the hypothesis that RIPC prevents the decrease in endothelial function observed after strenuous exercise in healthy men. In a randomized, crossover study, 13 healthy men performed running exercise preceded by RIPC of the lower limbs (4 × 5-min 220-mmHg bilateral occlusion) or a sham intervention (sham; 4 × 5-min 20-mmHg bilateral occlusion). Participants performed a graded maximal treadmill running test, followed by a 5-km time trial (TT). Brachial artery endothelial function was examined before and after RIPC or sham, as well as after the 5-km TT. We measured flow-mediated dilation (FMD), an index of endothelium-dependent function, using high-resolution echo-Doppler. We also calculated the shear rate area-under-the-curve (from cuff deflation to peak dilatation; SR(AUC)). Data are described as mean and 95% confidence intervals. FMD changed by 0.30). In the sham trial, FMD changed from 5.1 (4.4-5.9) to 3.7% (2.6-4.8) following the 5-km TT (P = 0.02). In the RIPC trial, FMD changed negligibly from 5.4 (4.4-6.4) post-IPC and 5.7% (4.6-6.8) post 5-km TT (P = 0.60). Baseline diameter, SR(AUC), and time-to-peak diameter were all increased following the 5-km TT (P < 0.05), but these changes did not influence the IPC-mediated maintenance of FMD. In conclusion, these data indicate that strenuous lower-limb exercise results in an acute decrease in brachial artery FMD of ~1.4% in healthy men. However, we have shown for the first time that prior RIPC of the lower limbs maintains postexercise brachial artery endothelium-dependent function at preexercise levels.