Ischemic preconditioning improves skeletal muscle blood flow and vasodilation during exercise in older adults

Aging is associated with reduced blood flow responses in contracting skeletal muscle partially attributed to an impaired ability to offset sympathetically mediated vasoconstriction, a process known as functional sympatholysis (FS). Ischemic preconditioning (IPC), characterized by cyclical bouts of occlusion and reperfusion, applied both locally and/or remotely improves vascular function, including measures of FS in young healthy adults. However, it is unknown whether IPC is effective at improving FS in a population with blunted exercise blood flow responses and impaired FS. Therefore, we tested the hypothesis that IPC would improve FS and exercise hyperemia in an aging population. Eleven older adults (64±7 years; 6 females/5 males) completed rhythmic handgrip exercise trials (15% maximal voluntary contraction) before and after one of three intervention periods: remote IPC (non-exercising arm), local IPC (exercising arm), or time control (TC). IPC interventions involved four cycles of 5 min upper arm occlusion followed by 5 min reperfusion, whereas TC involved no cuff occlusion. Lower body negative pressure (LBNP) was used to elicit sympathetic mediated vasoconstriction during the handgrip trials. Forearm blood flow (FBF; mL/min) was measured via Doppler ultrasound, with forearm vascular conductance (FVC; ml·min-1·100 mmHg-1) calculated as the quotient of FBF and mean arterial pressure. Percent (%) change in FVC in response to LBNP during handgrip exercise was used to assess FS. Local IPC reduced %FVC (-15.4±4.1 to -9.3±5.4%, P< 0.01), whereas no change was observed with remote IPC (-13.4±3.4 to -11.9±2.5%, P=0.11) and TC (-14.4±3.5 to -13.8±4.1%, P=0.52). Additionally, the change (Δ) in FBF (154±61 to 182±59 ml/min, P< 0.01) and FVC (151±59 to 174±60 ml·min-1·100 mmHg-1, P< 0.01) from baseline to steady state exercise were increased following local IPC, but remained unchanged following remote IPC (ΔFBF 162±59 to 165±56 ml/min; ΔFVC 157±62 to 157±62 ml·min-1·100 mmHg-1, P=0.65 and 0.88 respectively) or TC (ΔFBF 166±57 to 167±55 ml/min; ΔFVC 171±67 to 162±61 ml·min-1·100 mmHg-1, P=0.84 and 0.16 respectively). Our data demonstrate that application of local IPC acutely improves FS and exercise hyperemia in contracting skeletal muscle of older adults. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.