Background Advancing age is associated with increased risk for cardiovascular diseases (CVD), cognitive decline, Alzheimer's disease and related dementias. Part of this risk may be driven by age-related increases in systolic blood pressure (SBP) and subsequent cerebrovascular dysfunction. Habitual aerobic exercise lowers SBP and promotes cerebrovascular health; however, lack of time and other barriers limit adherence to physical activity guidelines in the majority of adults. High-resistance inspiratory muscle strength training (IMST; 30 inhalations/session against resistance), is a time-efficient, highly-adherable lifestyle intervention for lowering SBP and improving peripheral vascular function in midlife/older (ML/O; ≥50 years) adults with initial above-normal SBP (i.e., ≥120 mmHg). However, whether IMST improves cerebrovascular function in this at-risk population is unknown. Purpose: To determine if high-resistance IMST improves measures of cerebrovascular function in ML/O adults with initial above-normal SBP. We hypothesized 6 weeks of high-resistance IMST would improve cerebrovascular function vs. low-resistance Sham training. Methods: Cerebrovascular function was measured in 16 ML/O adults before and after 6 weeks of high-resistance IMST (30 breaths/day, 6 days/week, 75% maximal inspiratory pressure [PIMAX]) (n=9, 4F/5M, 65 ± 3 years) or Sham training (15% PIMAX, n=7, 2F/5M, 63 ± 2 years). Middle cerebral artery blood velocity (MCAv) was measured with a 2-MHz transcranial Doppler probe during 5 minutes each of normocapnia and hypercapnia (5% CO2, balanced nitrogen). Cerebrovascular reactivity (CVR), a measure of cerebrovascular responsiveness to a vasoactive stimulus, was determined as ΔMCAv/Δend-tidal CO2 between normocapnia and hypercapnia and interpreted as an index of cerebrovascular health. To account for potential changes in perfusion pressure, CVR was normalized to the change in mean arterial BP from normocapnia to hypercapnia and expressed as cerebrovascular conductance index (CVCi) reactivity. Pulsatility index, a marker of cerebrovascular stiffness, was calculated as (MCAvsystole – MCAvdiastole)/MCAvmean. Results: CVR was significantly increased after 6 weeks of IMST (pre: 1.38 ± 0.22 cm/s/mmHg, post: 2.31 ± 0.34 cm/s/mmHg; p=0.04), but not Sham training (pre: 1.20 ± 0.08 cm/s/mmHg, post: 1.48 ± 0.23 cm/s/mmHg; p=0.75). As a result, CVR was higher in the IMST group vs. Sham after the intervention period (p=0.06). CVCi reactivity also was significantly higher after IMST (pre: 0.009 ± 0.002 cm/s/mmHg2, post: 0.018 ± 0.004 cm/s/mmHg2; p=0.05), but not Sham training (pre: 0.009 ± 0.001 cm/s/mmHg2, post: 0.010 ± 0.002 cm/s/mmHg2; p=0.90). Pulsatility index did not change in either group (all p>0.05). Conclusion: These preliminary findings suggest high-resistance IMST is a promising, time-efficient intervention for improving select measures of cerebrovascular function in ML/O adults with initial above-normal SBP, a cohort at high risk for future CVD and cognitive decline.