title: 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.
authors.affiliation: Department of Kinesiology, McMaster University, Hamilton, ON, Canada. cmcgowan@uhnres.utoronto.ca
authors.forename: Cheri L
authors.initials: CL
authors.lastname: McGowan
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Levy
authors.forename: Neil
authors.initials: N
authors.lastname: McCartney
authors.forename: Maureen J
authors.initials: MJ
authors.lastname: MacDonald
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001794:Blood Pressure / Q000502:physiology; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000502:physiology*; D016022:Case-Control Studies; D005260:Female; D006225:Hand; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D017078:Laser-Doppler Flowmetry; D008297:Male; D026741:Physical Therapy Modalities; D012039:Regional Blood Flow / Q000502:physiology; D014463:Ultrasonography; D014664:Vasodilation / Q000502:physiology*