Different mechanisms of blood pressure regulation during dynamic and isometric exercise tasks in chronic stroke survivors

Study Objective: Mean arterial pressure (MAP) is the product of cardiac output (CO) and total peripheral resistance (TPR). In healthy individuals, the pressor response during exercise is primarily driven by increased CO rather than increased TPR. Our objective was to investigate whether chronic stroke survivors (≥6 months post-stroke), who exhibit reduced exercise capacity, increase MAP via elevated TPR vs. CO during dynamic and isometric single-limb exercise tasks. Hypothesis: We hypothesized that chronic stroke survivors would increase MAP during exercise by increasing TPR vs. CO. We further hypothesized that stroke survivors with mild physical disability would increase MAP predominantly through increases in CO, whereas stroke survivors with moderate to severe disability would rely more on increases in TPR. Methods: Participants performed maximum voluntary isometric contractions (MVICs) of the knee extensors and flexors to determine peak torque in the paretic and non-paretic legs. Single-limb knee extension and flexion exercises were then performed on a Biodex dynamometer at 30% MVIC for 3 minutes under dynamic (repeated knee flexion and extension) or isometric (sustained knee extensor contraction) conditions. MAP, heart rate (HR), CO, and TPR were continuously measured using a non-invasive finger blood pressure cuff. Results: Nine chronic stroke survivors (4 F; age 59±11 years, 9±7 years post-stroke) completed all testing sessions. There were no differences in MAP or HR at rest, or ΔMAP or ΔHR from rest to the end of the exercise tasks regardless of exercise modality or limb (p >0.05). During dynamic exercise, an increase in CO was observed in both the paretic leg (ΔCO = 0.9±1.0 L/min) and non-paretic leg (ΔCO = 2.0±1.6 L/min), with minimal change in TPR (ΔTPR = 0.1±0.5 mmHg•s/mL paretic; -0.1±0.4 mmHg•s/mL non-paretic). Conversely, during isometric exercise, little change in CO was observed when exercise was performed with either the paretic (ΔCO = 0.4±1.0 L/min) or non-paretic leg (ΔCO = 0.1±1.2 L/min). However, TPR increased during isometric exercise in both limbs (ΔTPR = 0.5±0.8 mmHg•s/mL paretic; 0.7±1.2 mmHg•s/mL non-paretic). Moderately strong positive correlations were observed between ΔCO during paretic leg dynamic exercise and (1) self-selected walking speed (r2=0.38; p=0.11), (2) 6-minute walk test distance (r2=0.20; p=0.31), and (3) knee extensor strength (r2=0.28; p=0.18). Strong positive correlations were found between ΔCO and fast walking speed (r2=0.51; p=0.05) and lower extremity Fugl-Meyer score (r2=0.58; p=0.03). Conclusion: Chronic stroke survivors regulate the exercise pressor response in a task-dependent manner, with dynamic exercise eliciting CO-driven increases in MAP and isometric exercise relying on increased TPR. Greater increases in CO during paretic leg dynamic exercise were positively associated with faster walking speeds and higher clinical scores, suggesting that preserved cardiovascular adaptability during dynamic activity may be critical for functional mobility after stroke. Funding Source: This project was supported by NIH-NICHD grant R01HD118661 (to M.J.D. and A.S.H.). 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.