Effects of Isometric Handgrip Training on Home Blood Pressure Measurements in Hypertensive Patients: A Randomized Crossover Study

Objective We aimed to examine the effects of isometric handgrip (IHG) training on home blood pressure (BP) levels in hypertensive Japanese patients undergoing treatment. Methods Fifty-three hypertensive patients (mean age, 61.7 years; 56.6% men) with a home systolic BP ≥135 mmHg and/or a home diastolic BP ≥85 mmHg were randomly assigned to either group A or B. As per the crossover design, group A performed 8 weeks of IHG training, followed by an equivalent training-free, control period, while the reverse protocol was performed by group B. The baseline characteristics were similar between both groups. The individualized daily IHG training comprised four sets of 2-min isometric contractions at 30% of the individual's maximum voluntary contraction capacity, including 1 min of rest between sets, for ≥3 days/week. The outcome measure was morning and evening home BP readings taken over the last 2 weeks of the training and control periods. Results A combined data analysis for both groups showed that IHG training was significantly associated with the lowering of both systolic and diastolic BP in the morning (137.9±9.3 vs. 135.3±9.5 mmHg, p=0.007 and 83.0±9.5 vs. 81.2±9.3 mmHg, p<0.001, respectively) and evening (130.0±10.7 vs. 127.6±10.1 mmHg, p=0.003 and 75.8±10.4 vs. 73.8±9.2 mmHg, p<0.001, respectively), while no significant change was observed after the control period. A larger increase in the maximum grip strength due to IHG training was associated with greater BP reductions. Conclusion An 8-week period of IHG training significantly lowered both the morning and evening home BP in hypertensive Japanese patients undergoing treatment.