Effects of 8-Week Isometric Handgrip Exercise on Aortic Distensibility and Central Cardiovascular Responses

Abstract

<p> Recent evidence suggests that isometric handgrip training improves resting arterial blood pressure (BP) in normotensive and hypertensive individuals, however the mechanisms remain elusive. The purposes of the current investigation were to replicate the finding that 8 weeks of isometric handgrip training (IHG) improve resting BP in persons medicated for hypertension, to determine if training could improve aortic stiffness and to examine the acute cardiovascular response to IHG. Seventeen participants were recruited and familiarized with the laboratory and techniques used. Training consisted of 8 weeks of thrice weekly IHG training sessions using a pre-programmed handgrip dynamometer (4, 2-minute contractions separated by 4 minutes rest). Measurements of resting ABP (assessed by automated oscillometry), aortic stiffness (assessed by simultaneous ultrasound and applanation tonometry), and the acute cardiovascular response (heart rate, blood pressure, rate-pressure product, and cardiac output) were made at baseline and following 8 weeks of IHG training.</p> <p> Following training, there were no differences observed in resting systolic or diastolic systolic blood pressure, resting heart rate or cardiac output. Furthermore, handgrip training did not improve aortic distensibility or reduce stiffness index. The acute responses of heart rate, blood pressure, rate pressure product and cardiac output were not altered with training. In response to an acute bout of IHG there were significant increases seen in heart rate (55±2 to 65±3 BPM, p<0.01), blood pressure (systolic: 137.2±3.7 to 157.1±7.3; diastolic: 77.8±3.4 to 92.2±4.8 mmHg, p<0.01) and rate-pressure product (7369.4±302.0 to 10159.0±666.6 beatsxmmHg/min). Thus isometric handgrip training is a safe modality which does not appear to alter the stiffness of the proximal aorta or generate a significant cardiovascular strain in the acute phase.</p>