The efficacy of isometric resistance training utilizing handgrip exercise for blood pressure management: A randomized trial

Introduction: Hypertension is a major risk factor contributing to cardiovascular disease, which is the number one cause of deaths worldwide. Although antihypertensive medications are effective at controlling blood pressure, current first-line treatment for hypertension is nonpharmacological lifestyle modifications. Recent studies indicate that isometric resistance training (IRT) may also be effective for assisting with blood pressure management. The aim of this study was to determine the efficacy of IRT for blood pressure management and the suitability of a low-intensity working control group. Methods: Forty hypertensive individuals, aged between 36 and 65 years, conducted IRT for 8 weeks. Participants were randomized into 2 groups, working at an intensity of either 5% or 30% of their maximum voluntary contraction. Participants performed 4x2minute isometric handgrip exercises with their nondominant hand, each separated by a 3-minute rest period, 3 days a week. Results: Blood pressure measurements were conducted at baseline and at the end of the protocol using a Finometer. Eight weeks of isometric resistance training resulted in a 7-mmHg reduction of resting systolic blood pressure (SBP) (136±12 to 129±15; P= 0.04) in the 30% group. Reductions of 4mmHg were also seen in mean arterial pressure (MAP) (100±8 to 96±11; P=0.04) in the 30% group. There were no statistically significant reductions in diastolic blood pressure for the 30% group, or any of the data for the 5% group. Conclusion: Isometric resistance training conducted using handgrip exercise at 30% of maximum voluntary contraction significantly reduced SBP and MAP. A lack of reduction in blood pressure in the 5% group indicates that a low-intensity group may be suitable as a working control for future studies. Abbreviations: ANCOVA = analysis of covariance, ANOVA = analysis of variance, CVD = cardiovascular disease, DBP = diastolic blood pressure, HR = heart rate, IRT = isometric resistance training, MANOVA = multivariate analysis of variance, MAP = mean arterial pressure, MVC = maximum voluntary contraction, SBP = systolic blood pressure, sec = second.