The Impact Of Aerobic Fitness On Isometric Handgrip-Mediated Assessment Of Sympathetic Transduction
Bibliographic record
Abstract
Sympathetic transduction can be quantified by the magnitude of peak pressor/vascular resistance responses to muscle sympathetic nerve activity (MSNA). Blunted sympathetic transduction has been observed in more aerobically fit middle-aged males assessed via the relationship between lower-body negative pressure-induced increases in MSNA and forearm vascular resistance. However, it is unknown whether aerobic fitness impacts stressor evoked sympathetic transduction in younger adults. PURPOSE: To test the hypothesis that higher aerobic fitness is associated with blunted sympathetic transduction responses assessed via isometric handgrip exercise (IHG). We also explored the association between aerobic fitness with peak MSNA and diastolic blood pressure (DBP) responses to IHG. METHODS: In 12 younger adults (7♀, 25 ± 7 years), relative peak oxygen consumption (V̇O2peak) was determined via indirect calorimetry from a graded maximal cycling test (40.7 ± 6.9 mLO2/kg/min). Beat-by beat DBP (via finger photoplethysmography) and peroneal MSNA burst frequency (via microneurography) were recorded during supine rest and throughout IHG. Following a 2-min baseline period, the IHG protocol involved a sustained contraction at 35% of maximal voluntary force (141 ± 43 s, 71-201 s) until fatigue (visual feedback provided). DBP and MSNA data were averaged over the baseline period and in minimum 30-sec bins throughout IHG. The slope of the DBP-MSNA relationship quantified transduction. Peak DBP and MSNA responses during IHG (from baseline) were also recorded. RESULTS: There was no relationship between aerobic fitness (29.7-52.5 mLO2/kg/min) and IHG-determined sympathetic transduction (Mean: 0.55 ± 0.15 mmHg/bursts/min, P = 0.801, R = -0.077). Similarly, there was no association between aerobic fitness versus the peak MSNA (+22 ± 11 bursts/min, P = 0.450, R = 0.230) or DBP (+16 ± 5 mmHg, P = 0.171, R = 0.404) responses to IHG. CONCLUSIONS: These results suggest that aerobic fitness does not impact IHG-mediated sympathetic transduction in a small sample of young adults (7/12 females). Sex differences exist regarding the relationship between aerobic fitness versus sympathetic transduction, peak MSNA and pressor responses (inverse relationships in males only), which warrants future exploration.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| 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) | 0.002 | 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 source (direct Gemma or distilled Codex), 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".