Is there a relationship between resting sympathetic nerve activity and leg vascular conductance in aerobically‐trained older adults?
Bibliographic record
Abstract
Inactivity is associated with elevated resting muscle sympathetic nerve activity (MSNA) that directly relates to corresponding reductions in leg vascular conductance (LVC) as one ages. Aerobic training further increases resting MSNA but also augments nitric oxide (NO) bioavailability assessed via the flow‐mediated dilation (FMD) response. How these competing vascular mechanisms contribute to sympathetic‐transduction in older active adults is unclear. We tested the hypothesis that parallel increases in aerobic fitness, lower limb MSNA and FMD would negate the inverse relationship between MSNA and LVC in older active adults. We measured fibular MSNA (microneurography), popliteal artery blood flow (PBF) and FMD (Doppler ultrasound) in 16 (10♂, 25.8 ± 3.1 kg•m −2 ) older (64 ± 5 years), aerobically‐trained adults (152 ± 37% age‐predicted VO 2 peak). LVC was calculated as PBF/mean arterial pressure. Resting MSNA burst frequency and relative popliteal artery (PA)‐FMD were 31 ± 15 burst•min −1 and 9.2 ± 3.1%, respectively. Aerobic fitness correlated positively with both MSNA (r=0.56; p=0.03) and relative PA‐FMD (r=0.87; p=0.01). MSNA correlated with PA‐FMD (r=0.60; p=0.02) but not with resting LVC (r=0.02; p=0.94). Similarly, PA‐FMD did not relate to resting LVC (r=−0.01; p=0.96). The main findings include: 1) resting MSNA and PA‐FMD were significantly associated with aerobic fitness in active older adults, and 2) unlike their sedentary peers, LVC was not inversely related to resting MSNA in aerobically‐trained older adults. This latter finding may be due to reduced transduction of the sympathetic vasoconstrictor signal mediated, in part, by a corresponding increase in basal NO bioavailability Support or Funding Information Support provided by: Canadian Foundation for Innovation: Leaders Opportunity Fund, Faculty of Health Professions Research Development, and Nova Scotia Health Research Foundation Development/Innovation grants.
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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 | 0.002 |
| 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 | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".