Isometric handgrip training for 8 weeks improved resting brachial artery flow-mediated dilation (P < 0.01) without changing nitroglycerin-mediated maximal vasodilation in medicated hypertensives.
Does isometric handgrip training improve brachial artery flow-mediated dilation in patients medicated for hypertension?
An 8-week isometric handgrip training program improves resting endothelium-dependent vasodilation in medicated hypertensive patients, despite transient acute impairments following single exercise bouts.
p-value: p=<0.01
Previous work from our laboratory demonstrated that isometric handgrip (IHG) training improved local, endothelium-dependent vasodilation in medicated hypertensives McGowan CL (PhD Thesis), 2006; McGowan et al. Physiologist 47: 285, 2004. We investigated whether changes in the capacity of smooth muscle to dilate (regardless of endothelial factors) influenced this training-induced change, and we examined the acute vascular responses to a single bout of IHG. Seventeen subjects performed four 2-min unilateral IHG contractions at 30% of maximal voluntary effort, three times a week for 8 wk. Pre- and posttraining, brachial artery flow-mediated dilation (FMD, an index of endothelium-dependent vasodilation) and nitroglycerin-mediated maximal vasodilation (an index of endothelium-independent vasodilation) were measured in the exercised arm by using ultrasound before and immediately after acute IHG exercise. IHG training resulted in improved resting brachial FMD (P < 0.01) and no change in nitroglycerin-mediated maximal vasodilation. Pre- and posttraining, brachial artery FMD decreased following an acute bout of IHG exercise (normalized to peak shear rate, pre-, before IHG exercise: 0.01 +/- 0.002, after IHG exercise: 0.008 +/- 0.002%/s(-1); post-, before IHG exercise: 0.020 +/- 0.003, after IHG exercise: 0.010 +/- 0.003%/s(-1); P < 0.01). Posttraining, resting brachial artery FMD improved yet nitroglycerin-mediated maximal vasodilation was unchanged in persons medicated for hypertension. This suggests that the training-induced improvements in the resting brachial artery FMD were not due to underlying changes in the forearm vasculature. Acute IHG exercise attenuated brachial artery FMD, and although this impairment may be interpreted as hazardous to medicated hypertensives with already dysfunctional endothelium, the effects appear transient as repeated exposure to the IHG stimulus improved resting endothelium-dependent vasodilation.
McGowan et al. (Sat,) conducted a other in Medicated hypertension (n=17). Isometric handgrip (IHG) training vs. Pre-training baseline was evaluated on Resting brachial artery flow-mediated dilation (FMD) (p=<0.01). Isometric handgrip training for 8 weeks improved resting brachial artery flow-mediated dilation (P < 0.01) without changing nitroglycerin-mediated maximal vasodilation in medicated hypertensives.