Effects of the Intensity, Duration, and Muscle Mass of Isometric Handgrip Exercise on Neuromuscular Fatigue and Post‐Exercise Blood Pressure Responses: A Crossover Study

Background: Isometric handgrip exercise (IHE) has emerged as a promising nonpharmacological intervention for blood pressure management. The objective of this study was to investigate the influence of the intensity, duration, and muscle mass factors of IHE protocol variation on the relationship between neuromuscular fatigue and blood pressure changes (systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR)). Methods: Sixteen participants completed one standard protocol (A) and three protocol variations (B, C, and D) in four visits separated by 7 days between visits. The protocols included: (A) unilateral IHE at 30% maximal voluntary contraction (MVC) for 2 min for four bouts, (B) unilateral IHE at 45% MVC for 2 min for four bouts, (C) unilateral IHE at 30% MVC for 3 min for four bouts, and (D) bilateral IHE at 30% MVC for 2 min for four bouts. The root mean square (RMS) and median frequency (MDF) of surface electromyography were used to quantify muscle fatigue of the flexor digitorum superficialis (FDS), extensor carpi radialis longus (ECR), flexor carpi ulnaris (FCU), and extensor carpi ulnaris (ECU). Results: < 0.05). Conclusion: The results of this study suggest that fatigue of ECR and FDS may affect the efficacy of cardiovascular responses by isometric contraction exercise training.