Blood-flow restriction eliminates sex differences in heart rate responses during leg exercise in healthy adults

Background: The augmented exercise pressor reflex (EPR), a characteristic feature of cardiovascular diseases like peripheral arterial disease (PAD), may contribute to adverse cerebral and cardiovascular events. Blood flow restriction (BFR) provides a model for limb ischemia, simulating the hemodynamic environment of PAD. This approach may help examine the EPR in PAD. Prior studies have reported sex differences in EPR, with premenopausal women exhibiting attenuated pressor responses. Moreover, sex differences in PAD, including clinical manifestation and prognosis, have also been reported. However, sex differences in hemodynamic variables during leg exercise under BFR conditions remain unknown. We hypothesized that men and women would exhibit different patterns of hemodynamic responses to leg exercise under BFR in healthy adults. Method: Eight men (38 ± 7 yr) and 13 women (36 ± 8 yr) performed static plantar flexion exercise to fatigue at 80% MVC under randomized free flow (FF) and BFR (cuff pressure: 100 mmHg above resting systolic blood pressure) conditions. Post-exercise circulatory occlusion (PECO) was followed immediately for 1 minute. Beat-by-beat blood pressure (BP, Finometer) and heart rate (HR, ECG) were recorded throughout the study. Stroke volume (SV), cardiac output (CO), and total peripheral resistance (TPR) were estimated using the Modelflow method (Finometer). Results: Subject characteristics and baseline hemodynamic variables did not differ between the sex groups. HR and BP increased significantly during the exercise paradigm in both groups and both conditions. HR responses (changes from rest) did not differ between the FF and BFR conditions. A sex-related difference in HR responses was detected under the FF condition (two-way ANOVA, sex effect, p = 0.043), whereas no significant sex-by- exercise stage interaction was observed during BFR (p > 0.05). There was no difference in mean arterial pressure (MAP) responses in BFR and FF (p > 0.05). No significant sex differences were found in MAP responses under either FF or BFR conditions (p > 0.05). No significant sex differences were found in the responses of SV, CO, or TPR under either FF or BFR conditions (all p > 0.05). Discussion & Conclusion: Present data show that BFR abolished the sex-related differences in HR responses observed under FF conditions. This finding suggests that the mechanisms underlying sex differences in the EPR during normal perfusion may be neutralized or overridden when perfusion is restricted. Further studies are warranted to examine sex differences in autonomic control under these conditions, and to determine whether these factors contribute to sex differences in PAD. Supported by NIH R01HL164571 and R01HL144781 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.