Key result
Beta-adrenergic blockade attenuated heart rate increases during partial flow restriction in leg cycling (Δ4 vs Δ11 beats/min in control; P<0.05), showing metaboreflex relies on sympathetic activity.
Why the study?
Does autonomic blockade alter the heart rate response to muscle metaboreflex activation in healthy males?
Population
8 male participants, mean age 22 ± 3 years
Comparison
β1-adrenergic blockade and parasympathetic… vs Control condition during the same exercise…
Design
Other
Authors
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Caution against clinical extrapolation; extends mechanistic evidence for sympathetic metaboreflex control in healthy adults.
Does autonomic blockade alter the heart rate response to muscle metaboreflex activation in healthy males?
p-value: p=<0.05
Muscle metaboreflex activation-mediated increases in heart rate are principally driven by increased cardiac sympathetic activity, with parasympathetic withdrawal contributing only after large muscle mass exercise.
Fisher et al. (2013) studied this question. Beta-1-adrenergic blockade (metoprolol) and parasympathetic blockade (glycopyrrolate) vs. Control (no drug) was evaluated on Change in heart rate during enhanced metaboreflex activation with partial flow restriction (p=<0.05). Beta-adrenergic blockade attenuated heart rate increases during partial flow restriction in leg cycling (Δ4 vs Δ11 beats/min in control; P<0.05), showing metaboreflex relies on sympathetic activity.
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