Isometric handgrip training does not improve flow-mediated dilation in subjects with normal blood pressure

Abstract

Isometric HG (handgrip) training lowers resting arterial BP (blood pressure), yet the mechanisms are elusive. In the present study, we investigated improved systemic endothelial function as a mechanism of arterial BP modification following isometric HG training in normotensive individuals. This study employed a within-subject repeated measures design primarily to assess improvements in BA FMD (brachial artery flow-mediated dilation; an index of endothelium-dependent vasodilation), with the non-exercising limb acting as an internal control. Eleven subjects performed four 2-min unilateral isometric HG contractions at 30% of maximal effort, three times per week for 8 weeks. Pre-, mid- and post-training resting ABP and BA FMD (exercised arm and non-exercised arm) were measured via automated brachial oscillometry and ultrasound respectively. BA FMD (normalized to the peak shear rate experienced in response to the reactive hyperaemic stimulus) remained unchanged [exercised arm, 0.029+/-0.003 to 0.026+/-0.003 to 0.029+/-0.004%/s(-1) (pre- to mid- to post-training respectively); non-exercised arm, 0.023+/-0.003 to 0.023+/-0.003 to 0.024+/-0.003%/s(-1) (pre- to mid- to post-training respectively); P=0.22]. In conclusion, improved systemic endothelial function is unlikely to be responsible for lowering arterial BP in this population.

Home-based isometric exercise training induced reductions resting blood pressure

“…The resting BP reductions are similar in magnitude to those previously reported following IET that was partly laboratory-based with participants performing constant force contractions (McGowan et al 2007a;Millar et al 2013a) and completely laboratory-based using constant EMG contractions (Devereux et al 2010;Wiles et al 2010;Gill et al 2015). Furthermore, the rate of reduction in all resting BP parameters occurred at either a faster or equal rate (Devereux et al 2010) to that reported previously in normotensive participants following bilateral-leg IET using the same acute programme variables and exercise intensity in a laboratory setting.…”

The effects of performing isometric training at two exercise intensities in healthy young males

“…It is well established that isometric exercise training (IET) causes a reduction in resting blood pressure (BP) (Wiley et al 1992;Ray and Carrasco 2000;Howden et al 2002;Taylor et al 2003;McGowan et al 2004McGowan et al , 2006bMcGowan et al , 2007Visocchi et al 2004;Millar et al 2008). However, there has not been any systematic exploration of the extent to which the intensity of this training influences these reductions.…”

Reductions in ambulatory blood pressure in young normotensive men and women after isometric resistance training and its relationship with cardiovascular reactivity

“…This recommendation was founded in the accumulating evidence of the efficacy of IRT in reducing resting BP in individuals with and without HT, including those medicated for HT and those who exercise regularly [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Early evidence also suggests that IRT may be particularly effective in older women versus agematched men [19], and has a positive influence on ambulatory BP [20]; a comprehensive measure of BP that provides insight into 24 hour BP fluctuations.…”