What question did this study set out to answer?

To elucidate the distinct roles of the parasympathetic and sympathetic nervous systems in mediating heart rate and blood pressure responses during sustained isometric handgrip exercise.

July 1, 1974Journal of Clinical InvestigationOpen Access

Autonomic Mechanisms in Hemodynamic Responses to Isometric Exercise

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Why the study?

What is the role of the autonomic nervous system in hemodynamic responses to sustained isometric exercise in young adult males?

Population

Young adult male volunteers

Comparison

Selective autonomic blockade with intravenous… vs Unblocked responses (implied)

Design

Other

Follow-up

3 minutes (duration of handgrip)

Authors

CMC. Edwin MartinThomas Jefferson University Hospital JSJames A. ShaverUniversity of Pittsburgh DLDonald F. LeonUniversity of Pittsburgh

Discussion

Member takes

Implication

Clarifies sequential vagal-sympathetic control of HR and BP during isometric exercise; hypothesis-generating for autonomic modulation in cardiovascular conditions.

Key Points

To elucidate the distinct roles of the parasympathetic and sympathetic nervous systems in mediating heart rate and blood pressure responses during sustained isometric handgrip exercise.
Administered selective intravenous autonomic blockades using propranolol, cardioselective practolol, atropine, and combined atropine-propranolol in young adult male volunteers.
Assessed cardiovascular hemodynamics during sustained isometric handgrip exercise performed at 30% of maximal voluntary contraction for 3 minutes.
Tachycardia initiation during the first 30 seconds was mediated by vagal withdrawal and blocked by atropine, whereas heart rate elevation during the mid-to-late phases was sympathetic and required combined atropine-propranolol for suppression.
Handgrip increased blood pressure via heightened cardiac output without altering systemic vascular resistance in unblocked states, but beta-adrenergic blockade led to marked peripheral vasoconstriction without cardiac output increases.
Left ventricular ejection time index lengthened during handgrip, while preejection period prolonged following propranolol and shortened after atropine administration.

Structured PICO

What is the role of the autonomic nervous system in hemodynamic responses to sustained isometric exercise in young adult males?

Population

Young adult male volunteers

Intervention

Selective autonomic blockade with intravenous propranolol, practolol, atropine, and combined atropine-propranolol prior to handgrip sustained at 30% of maximal voluntary contraction for 3 min

Comparator

Unblocked responses (implied)

Outcome

Hemodynamic responses including heart rate, cardiac output, systemic vascular resistance, and arterial pressuresurrogate

The study delineates the sequential roles of vagal withdrawal and sympathetic stimulation in the heart rate and pressor responses to sustained isometric exercise.

Cite This Study

Martin et al. (1974) studied this question.

synapsesocial.com/papers/6a6f7161e71d69abee08040f https://doi.org/10.1172/jci107731

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Implication

Clarifies sequential vagal-sympathetic control of HR and BP during isometric exercise; hypothesis-generating for autonomic modulation in cardiovascular conditions.

Autonomic Mechanisms in Hemodynamic Responses to Isometric Exercise

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Autonomic Mechanisms in Hemodynamic Responses to Isometric Exercise

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Also Consider

Also Consider