The Effects of Six Weeks of Isometric Handgrip Training on Blood Pressure, The Autonomic Nervous System and Arterial Stiffness in Newly Diagnosed Hypertensives

Abstract

<p> Supervised isometric handgrip training (IHG) has been shown to lower blood pressure (BP) and therefore, may be an effective non-pharmacological treatment for hypertension. The present investigation examined the efficacy of unsupervised IHG to lower BP in patients who were recently diagnosed as hypertensive. Since the mechanisms responsible for attenuating BP remain unclear, this study also investigated the concurrent effects of IHG training on the autonomic nervous system (ANS) and arterial stiffness.</p> <p>Eight participants were randomized to the experimental group and the remaining six served as controls. Lifestyle modifications to lower BP were recommended for both groups. In addition, the experimental group completed IHG three times per week for six weeks. IHG consisted of four two-minute isometric contractions at 30% maximal voluntary contraction using alternate hands, each separated by a one-minute rest period. Pre- (PRE) and post-intervention (POST), BP was measured and the ANS was assessed by baroreceptor sensitivity (BRS) and both systolic and diastolic blood pressure variability (SBPV and DBPV) and arterial stiffness was evaluated by carotid-finger pulse wave velocity (PWV). All measures were assessed during a period of supine rest and during a 60° passive tilt.</p> <p> There were no significant changes in any BP measure from PRE to POST for either the experimental or control groups. There was a non-significant trend toward decreased heart rate (p = 0.065). BRS decreased from PRE to POST in both the experimental (10.7 ± 2.4 mm Hg to 9.7 ± 2.3 mm Hg) and control groups (8.6 ± 2.1 mm Hg to 7.6 ± 1.5 mm Hg), but there was no difference between groups. SBPV LF:HF was lower at POST than PRE in both experimental (6.8 ± 1.5 to 4.6 ± 1.1) and control (3.4 ± 1.9 to 2.3 ± 0.9), but there were no other differences in any other BPV variable. There were no significant changes in PWV.</p> <p> In conclusion, unsupervised IHG did not lower resting BP in newly diagnosed hypertensive patients, so there were no improvements in autonomic indices. There was a decrease in SBPV LF:HF indicating improved sympathovagal balance, but this was likely a result of lifestyle modification rather than IHG. Future studies are necessary to determine appropriate use of IHG as a treatment for hypertension and to verify the mechanisms responsible for BP attenuation with IHG.</p>