Impact of sympathetic nervous system activity on post‐exercise flow‐mediated dilatation in humans
Bibliographic record
Abstract
Key points Previous studies indicate a transient reduction in arterial function following large muscle group exercise, but the mechanisms involved are unknown. Sympathetic nervous system activation may contribute to such reductions through direct effects in the artery wall, or because of decreases in arterial shear stress. Administration of prazosin (an α 1 ‐adrenoreceptor blocker) abolished the transient reduction in vascular function observed under placebo conditions following exercise. This effect could not be explained by drug‐induced changes in arterial shear stress. These results suggest that sympathetic vasoconstriction directly competes with endothelium‐dependent dilator activity to influence post‐exercise vascular function. These findings have implications for understanding the stimuli responsible for exercise‐induced adaptations in arterial function and health in humans. Abstract Transient reduction in vascular function following systemic large muscle group exercise has previously been reported in humans. The mechanisms responsible are currently unknown. We hypothesised that sympathetic nervous system activation, induced by cycle ergometer exercise, would contribute to post‐exercise reductions in flow‐mediated dilatation (FMD). Ten healthy male subjects (28 ± 5 years) undertook two 30 min sessions of cycle exercise at 75% HR max . Prior to exercise, individuals ingested either a placebo or an α 1 ‐adrenoreceptor blocker (prazosin; 0.05 mg kg −1 ). Central haemodynamics, brachial artery shear rate (SR) and blood flow profiles were assessed throughout each exercise bout and in response to brachial artery FMD, measured prior to, immediately after and 60 min after exercise. Cycle exercise increased both mean and antegrade SR ( P < 0.001) with retrograde SR also elevated under both conditions ( P < 0.001). Pre‐exercise FMD was similar on both occasions, and was significantly reduced (27%) immediately following exercise in the placebo condition ( t ‐test, P = 0.03). In contrast, FMD increased (37%) immediately following exercise in the prazosin condition ( t ‐test, P = 0.004, interaction effect P = 0.01). Post‐exercise FMD remained different between conditions after correction for baseline diameters preceding cuff deflation and also post‐deflation SR. No differences in FMD or other variables were evident 60 min following recovery. Our results indicate that sympathetic vasoconstriction competes with endothelium‐dependent dilator activity to determine post‐exercise arterial function. These findings have implications for understanding the chronic impacts of interventions, such as exercise training, which affect both sympathetic activity and arterial shear stress.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".