The Effect of Muscle Blood Flow Restriction During Dynamic Exercise on Carotid Baroreflex Sensitivity

Background/Objectives: This study evaluated carotid baroreflex sensitivity (cBRS) during graded exercise tests to exhaustion in healthy individuals. It aimed to elucidate whether the augmented blood pressure response during heavy- and maximal-intensity dynamic exercise alters carotid baroreflex control of heart rate and contributes to exercise intolerance. Methods: Thirteen healthy males (age 33 ± 2 yrs, body mass 74.6 ± 2.4 kg, and V˙O2max 54.12 ± 1.88 mL·kg−1·min−1) performed a 4 min constant-load cycling exercise at low—(30% PPO), moderate—(60% PPO), high—(80% PPO), and maximal—(100% PPO) intensity, in two experimental conditions: (a) with unrestricted muscle blood flow (no-BFR) and (b) with partial muscle blood flow restriction (BFR). Results: A significant decline in cBRS was observed during the graded maximal exercise test compared to baseline (p < 0.001), accompanied by an upward and rightward relocation of the linear relationship between systolic blood pressure (SBP) and heart rate (HR). However, the magnitude of cBRS reduction was attenuated towards maximum exercise. Application of BFR during exercise exaggerated the blood pressure rise (p < 0.01), the perceptual response (p < 0.001), the exercise-induced cBRS reduction (p < 0.001), and induced a further relocation of the SBP-HR relationship. Additionally, BFR limited the HR increase and resulted in reduced exercise performance compared to the no-BFR condition. Conclusions: These findings suggest that the pronounced increase in blood pressure during heavy- and maximal-intensity exercise may limit further increases in heart rate through arterial baroreflex activation. This may contribute to reduced exercise tolerance, as evidenced by the lower peak power output and attenuated maximal heart rate observed in muscle BFR condition.