Effect of Lower- versus Higher-Intensity Isometric Handgrip Training in Adults with Hypertension: A Randomized Controlled Trial.

This study compared the effects of lower- versus higher-intensity isometric handgrip exercise on resting blood pressure (BP) and associated clinical markers in adults with hypertension. Thirty-nine males were randomly assigned to one of three groups, including isometric handgrip at 60% maximal voluntary contraction (IHG-60), isometric handgrip at 30% IHG-30, or a control group (CON) that had been instructed to continue with their current activities of daily living. The volume was equated between the exercise groups, with IHG-60 performing 8 × 30-s contractions and IHG-30 performing 4 × 2-min contractions. Training was performed three times per week for 8 weeks. Resting BP (median [IQR]), flow-mediated dilation, heart rate variability, and serum markers of inflammation and oxidative stress were measured pre- and post-intervention. Systolic BP was significantly reduced for IHG-60 (-15.5 mmHg [-18.75, -7.25]) and IHG-30 (-5.0 mmHg [-7.5, -3.5]) compared to CON ( p < 0.01), but no differences were observed between both the exercise groups. A greater reduction in diastolic BP was observed for IHG-60 (-5.0 mmHg [-6.0, -4.25] compared to IHG-30 (-2.0 mmHg [-2.5, -2.0], p = 0.042), and for both exercise groups compared to CON ( p < 0.05). Flow-mediated dilation increased for both exercise groups versus CON ( p < 0.001). IHG-30 had greater reductions in interleukin-6 and tumor necrosis factor-α compared to the other groups ( p < 0.05) and CON ( p = 0.018), respectively. There was a reduction in Endothelin-1 for IHG-60 compared to CON ( p = 0.018). Both the lower- and higher-intensity IHG training appear to be associated with reductions in resting BP and improvements in clinical markers of inflammation and oxidative stress.