Signaling Endothelial Reactivity Induced by Acute Hand Grip: Analyzing Vessel Diameter, Flow Velocity, and EMG Responses

Conventional occlusion-based flow-mediated dilation (FMD) for assessing endothelial reactivity (ER) faces challenges such as operator and/or subject-dependant variability and time constraints. This study proposes a novel method using acute hand grip (HG) exercise to induce shear stimulus for improved ER assessment. We analysed the signaling of endothelial and muscle reactivity through vessel diameter, flow velocity, and electromyography (EMG) responses. In a controlled study with 15 participants, a 30-second HG intervention induced significant changes: vessel diameter increased by 13.94%, flow velocity by 22.31%, and for EMG, the average rectified value (ARVEMG) by 87.44%. Baseline measurements included vessel diameter of 4.23 ± 0.38 mm, flow velocity of 10.91 ± 0.92 cm/s, and ARVEMG of 0.0011 ± 0.0003 mV. The acute HG method showed a moderate to high correlation with the traditional occlusion method (R<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> > 0.65, p <0.05) and comparable %FMD index (R<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> > 0.73, p < 0.05). Linear regression and Bland-Altman analysis confirmed strong agreement between methods. These results suggest that acute HG, focusing on vessel diameter, flow velocity, and EMG responses, is a viable, faster and efficient alternative for assessing endothelial reactivity, offering a practical solution for clinical settings.