Day‐to‐day Variability in Arterial Diameter and Brachial Artery Flow‐Mediated Dilation in Sedentary Young Men and Women
Bibliographic record
Abstract
Brachial artery flow‐mediated dilation (FMD), an index of endothelial function, is predictive of cardiovascular disease risk. A wide range of FMD day‐to‐day variability has been reported, but whether this variability differs between men and women is unknown. We examined potential sex‐based differences in FMD and its day‐to‐day variability. Sedentary but otherwise healthy men (N=10, age: 22±3 years) and women (N=7, age: 21±2 years) completed two brachial FMD tests 24 hours apart. Women were tested during the mid‐follicular phase of their menstrual cycle (days 7‐12). Baseline arterial diameter (AD BL ) and maximum reactive hyperemia diameter (AD RH ) were determined, and relative FMD was calculated as FMD% = (AD RH – AD BL )/AD BL . Day 1 measures and between‐day differences were assessed with independent t‐tests. Day‐to‐day variability was assessed with the coefficient of variation (CV) and intraclass correlation coefficient (ICC). Compared to men, women had smaller arterial diameters (p<0.05), but a similar FMD response (p=0.828). No sex‐differences were observed in between‐day differences for any measures (p>0.05). Day‐to‐day variability was low for AD in both sexes (CV of 3‐5%), but high for FMD (men: 43%, women: 55%). Similarly, ICCs were substantial to almost perfect for AD in both sexes (ICC of 0.77‐0.92), but poor for FMD (men: 0.01, women: 0.07). These findings suggest that arterial diameter exhibits better day‐to‐day repeatability than relative FMD in both men and women. Despite women having greater FMD variability than men, between‐day differences were not statistically significant. A larger sample size may be required to detect potential sex‐differences. Funded by NSERC, OGS and GSSI.
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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 | 0.001 | 0.002 |
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".