Isometric handgrip training improves local flow-mediated dilation in medicated hypertensives
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Bilateral isometric handgrip (IHG) training lowers resting arterial blood pressure (BP) in medicated hypertensives. Numerous mechanisms have been suggested, but have yet to be investigated. One such mechanism is that of improved systemic endothelial-dependent vasodilation. The purpose of this investigation was twofold: (1) to determine if Bilateral IHG training had any beneficial effects on endothelial-dependent vasodilation, and (2) to see if improved systemic endothelial-dependent vasodilation was responsible for lowering BP. Sixteen participants performed four, 2 min IHG contractions at 30% of their maximal voluntary effort, using either a Bilateral (n = 7) or a Unilateral IHG protocol (n = 9), three times per week for 8 weeks. Brachial artery (BA) flow-mediated dilation (FMD, an index of endothelial-dependent vasodilation, measured in both arms) was assessed pre-and post-training. Following Bilateral IHG training, BA FMD improved in both arms (normalized to peak shear rate, 0.005 ± 0.001 to 0.02 ± 0.002 s−1, P < 0.01). Following Unilateral IHG training, BA FMD improved in the trained arm only (normalized: 0.009 ± 0.002 to 0.02 ± 0.005 s−1, P < 0.01). These findings suggest that although IHG training improves endothelial-dependent vasodilation, the improvements occur only locally in the trained limbs. This suggests that enhanced systemic endothelial-dependent vasodilation is not the mechanism responsible for the observed post-IHG training reductions in BP in medicated hypertensives.
KeywordsEndothelium Exercise Hypertension Blood flow
Programmed Handgrip Dynamometers were loaned by Dr. Ron Wiley and MD Systems, Inc., Westerville, OH, USA. This investigation was supported by NSERC Canada (Grant) and the Heart and Stroke Foundation of Canada (Doctoral Fellowship Award).
- Corretti M, Anderson T, Benjamin E, Celermajer D, Charbonneau F, Creager M, Deanfield J, Drexler H, Gerhard-Herman M, Herrington D, Vallance P, Vita J, Vogel R (2002) Guidelines for the ultrasound assessment of endothelial-dependent flow-mediated vasodilation of the brachial artery. A report of the international brachial artery reactivity task force. J Am Coll Cardiol 39:257–265PubMedCrossRefGoogle Scholar
- Egashira K, Suzuki S, Hirooka Y, Kai H, Sugimachi M, Imaizumi T, Takeshita A (1995) Impaired endothelium-dependent vasodilation in large epicardial and resistance coronary arteries in patients with essential hypertension: different responses to acetylcholine and substance P. Hypertension 25:201–206PubMedGoogle Scholar
- Higashi Y, Sasaki S, Kurisu S, Yoshimizu A, Sasaki N, Matsuura H, Kajiyama G, Oshima T (1999a) Regular aerobic exercise augments endothelium-dependent vascular relaxation in normotensive as well as hypertensive subjects: role of endothelium-derived nitric oxide. Circulation 100:1194–1202Google Scholar
- Higashi Y, Sasaki S, Sasaki N, Nakagawa K, Ueda T, Yoshimizu A, Kurisu S, Matsurura H, Kajiyama G, Oshima T (1999b) Daily aerobic exercise improves reactive hyperemia in patients with essential hypertension. Hypertension 33:591–597Google Scholar
- McGowan CL (2006) Isometric handgrip training and arterial blood pressure: Effects and mechanisms. Ph D Thesis, McMaster University, HamiltonGoogle Scholar
- PAHI (2003) Pan American Hypertension Initiative. Working meeting on blood pressure measurement: suggestions for measuring blood pressure to use in population surveys. Pan Am J Public Health 14:300–302Google Scholar
- Stankevicius E, Kevelaitis E, Vainorius E, Simonsen U (2003) Role of nitric oxide and other endothelium-derived factors (Abstract). Medicina (Kaunas) 39:333Google Scholar
- Visocchi A, McGowan CL, Faulkner M, Verdun R, McCartney N, MacDonald J (2004) The effect of isometric arm or leg exercise on resting blood pressure and arterial distensibility in persons medicated for hypertension (Abstract). The Physiologist 47:278Google Scholar
- WHO (2003) 2003 World Health Organization/International Society of Hypertension statement on management of hypertension. J Hypertens 21:1983–1992Google Scholar