Individual differences in cardiac and vascular components of the pressor response to isometric handgrip exercise in humans

Watanabe, Kazuhito; Ichinose, Masashi; Tahara, Rei; Nishiyasu, Takeshi

doi:10.1152/ajpheart.00699.2013

Cited by 24 publications

(21 citation statements)

References 66 publications

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“…During isometric hand‐grip exercise, increased efferent drive from the cardio‐accelerator centres and afferent feedback from the muscle metaboreflex response cause an increase in arterial blood pressure and heart rate (Watanabe et al . ) and provide a safe, in vivo model to assess the impact of an acute pressure load on LV twist mechanics. However, increases in heart rate can independently influence LV twist (Buchalter et al .…”

Section: Introductionmentioning

confidence: 99%

The impact of an experimentally induced increase in arterial blood pressure on left ventricular twist mechanics

Balmain

Stewart

Yamada

et al. 2015

Experimental Physiology

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New Findings r What is the central question of this study?Increases in blood pressure elicited by isometric hand-grip exercise (IHG) have been shown to impair ventricular twist mechanics. However, the utility of the IHG model is confounded by a concurrent increase in heart rate, which independently influences ventricular mechanics. r What is the main finding and its importance?We show that a period of post-IHG circulatory occlusion isolates the effect of an arterial blood pressure increase from heart rate and magnifies the impairment of left ventricular twist when compared with IHG alone. A protocol using IHG followed by brief circulatory occlusion may serve as a useful tool in examining and understanding the relationships between afterload and cardiac function in various disease states.The effects of isometric hand-grip exercise (IHG) coupled with a period of postexercise circulatory occlusion (OCC; known to sustain exercise-induced increases in blood pressure while facilitating a decrease in heart rate) on left ventricular (LV) twist mechanics was examined. Two-dimensional speckle-tracking echocardiography was used to assess LV apical and basal rotation and LV twist in 19 healthy participants (23 ± 2 years old) at rest, during 3 min of IHG (performed at 40% maximal voluntary contraction) and 3 min of OCC immediately following IHG. The IHG elicited significant (P < 0.001) increases in mean arterial pressure (rest, 91 ± 1 mmHg; IHG, 122 ± 2 mmHg) and heart rate (rest, 65 ± 2 beats min −1 ; IHG, 91 ± 4 beats min −1 ). Mean arterial pressure remained elevated during OCC (116 ± 2 mmHg; P < 0.001 versus rest), whereas heart rate returned to resting levels (68 ± 3 beats min −1 ; P = 0.159 versus rest). Apical rotation decreased significantly (P < 0.01) by 10 ± 5% during IHG and 21 ± 4% during OCC, whereas basal rotation remained unchanged from rest. Left ventricular twist decreased from rest to IHG (12 ± 5%; P = 0.015) and OCC (21 ± 4%; P = 0.001), whereas a decrease in LV untwist rate was observed only during OCC. An increase in blood pressure generated by IHG, and maintained by a period of OCC, impairs aspects of LV twist mechanics. Postexercise circulatory occlusion isolated the effect of the arterial blood pressure rise (from heart rate), magnifying the impairment of LV twist mechanics when compared with IHG, whilst also negatively impacting LV relaxation. We propose that a protocol using isometric exercise followed by circulatory occlusion provides a method for studying the effects of blood pressure changes on LV twist mechanics.

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Section: Introductionmentioning

confidence: 99%

The impact of an experimentally induced increase in arterial blood pressure on left ventricular twist mechanics

Balmain

Stewart

Yamada

et al. 2015

Experimental Physiology

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“…The concomitant increase in BP and fall in SVR at the onset of isometric handgrip is well established (29), although the existence of individual differences has been reported (51). A cholinergic contribution to the SVR and BP responses to the onset of isometric handgrip may be explained by events in vascular beds other than that of the exercising skeletal muscle involved and given the rapidity of the response, a neural mechanism might be implicated (31).…”

Section: Discussionmentioning

confidence: 99%

A cholinergic contribution to the circulatory responses evoked at the onset of handgrip exercise in humans

Vianna

Fadel

Secher

et al. 2015

American Journal of Physiology-Regulatory, Integrative and Comp

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“…The box pressure was measured using a pressure transducer mounted on the box. We measured exercising LBF using Doppler ultrasound, as previously described (20,48). Briefly, a Doppler ultrasound system (HDI 5000; ATL Ultrasound, Bothell, WA) equipped with a hand-held transducer probe (model L12-5) with an operating frequency of 6 MHz was utilized to simultaneously measure two-dimensional common femoral artery diameter and mean blood velocity (MBV).…”

Section: Methodsmentioning

confidence: 99%

Increasing blood flow to exercising muscle attenuates systemic cardiovascular responses during dynamic exercise in humans

Ichinose

Ichinose-Kuwahara

Kondo

et al. 2015

American Journal of Physiology-Regulatory, Integrative and Comp

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Reducing blood flow to working muscles during dynamic exercise causes metabolites to accumulate within the active muscles and evokes systemic pressor responses. Whether a similar cardiovascular response is elicited with normal blood flow to exercising muscles during dynamic exercise remains unknown, however. To address that issue, we tested whether cardiovascular responses are affected by increases in blood flow to active muscles. Thirteen healthy subjects performed dynamic plantarflexion exercise for 12 min at 20%, 40%, and 60% of peak workload (EX20, EX40, and EX60) with their lower thigh enclosed in a negative pressure box. Under control conditions, the box pressure was the same as the ambient air pressure. Under negative pressure conditions, beginning 3 min after the start of the exercise, the box pressure was decreased by 20, 45, and then 70 mmHg in stepwise fashion with 3-min step durations. During EX20, the negative pressure had no effect on blood flow or the cardiovascular responses measured. However, application of negative pressure increased blood flow to the exercising leg during EX40 and EX60. This increase in blood flow had no significant effect on systemic cardiovascular responses during EX40, but it markedly attenuated the pressor responses otherwise seen during EX60. These results demonstrate that during mild exercise, normal blood flow to exercising muscle is not a factor eliciting cardiovascular responses, whereas it elicits an important pressor effect during moderate exercise. This suggests blood flow to exercising muscle is a major determinant of cardiovascular responses during dynamic exercise at higher than moderate intensity. integrated circulatory regulation; neural cardiovascular regulation; muscle metaboreflex DURING DYNAMIC EXERCISE, INCREASED skeletal muscle blood flow is essential to ensure an appropriate supply of O 2 to the active muscles and to remove the metabolic byproducts and generated heat. This exercise-induced skeletal muscle hyperemia is thought to be initially elicited by local mechanical and metabolic factors and to be modulated by neural cardiovascular regulatory mechanisms (8,41). Neural mechanisms also act to increase cardiac output (CO) and to redistribute blood flow from inactive regions to support the increase in skeletal muscle flow. This neural cardiovascular regulation is thought to be mediated by central command (41), as well as by feedback transmitted via afferent nerves (group III and IV fibers), innervating the working skeletal muscles, which are sensitive to mechanical (the so-called muscle mechanoreflex) and metabolic changes (the so-called muscle metaboreflex) (26,33,34,37,42), and are modulated via the arterial and cardiopulmonary baroreflexes (23,41,42).Reducing the blood flow to working muscles during dynamic exercise causes accumulation of metabolites within the active muscles and evokes muscle metaboreflex-mediated increases in sympathetic nerve activity, heart rate (HR), and systemic blood pressure (1,5,12,19,29,30,35,42). In addition, the reduced b...

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Individual differences in cardiac and vascular components of the pressor response to isometric handgrip exercise in humans

Cited by 24 publications

References 66 publications

The impact of an experimentally induced increase in arterial blood pressure on left ventricular twist mechanics

The impact of an experimentally induced increase in arterial blood pressure on left ventricular twist mechanics

A cholinergic contribution to the circulatory responses evoked at the onset of handgrip exercise in humans

Increasing blood flow to exercising muscle attenuates systemic cardiovascular responses during dynamic exercise in humans

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