Validity and reliability of measuring resting muscle sympathetic nerve activity using short sampling durations in healthy humans
Bibliographic record
Abstract
Resting muscle sympathetic nerve activity (MSNA) demonstrates high intraindividual reproducibility when sampled over 5-30 min epochs, although shorter sampling durations are commonly used before and during a stress to quantify sympathetic responsiveness. The purpose of the present study was to examine the intratest validity and reliability of MSNA sampled over 2 and 1 min and 30 and 15 s epoch durations. We retrospectively analyzed 68 resting fibular nerve microneurographic recordings obtained from 53 young, healthy participants (37 men; 23 ± 6 yr of age). From a stable 7-min resting baseline, MSNA (burst frequency and incidence, normalized mean burst amplitude, total burst area) was compared among each epoch duration and a standard 5-min control. Bland-Altman plots were used to determine agreement and bias. Three sequential MSNA measurements were collected using each sampling duration to calculate absolute and relative reliability (coefficients of variation and intraclass correlation coefficients). MSNA values were similar among each sampling duration and the 5-min control (all P > 0.05), highly correlated (r = 0.69-0.93; all P < 0.001), and demonstrated no evidence of fixed bias (all P > 0.05). A consistent proportional bias (P < 0.05) was present for MSNA burst frequency (all sampling durations) and incidence (1 min and 30 and 15 s), such that participants with low and high average MSNA underestimated and overestimated the true value, respectively. Reliability decreased progressively using the 30- and 15-s sampling durations. In conclusion, short 2 and 1 min and 30 s sampling durations can provide valid and reliable measures of MSNA, although increased sample size may be required for epochs ≤30 s, due to poorer reliability.
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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 | 0.005 | 0.017 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 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 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".