Substituting Stationary Time With Moderate-Intensity Activity May Improve Brachial Flow-Mediated Dilation: An Isotemporal Substitution Approach
Bibliographic record
Abstract
Brachial artery flow-mediated dilation (FMD) provides information regarding endothelial vasodilator function, with attenuated FMD responses indicative of higher cardiovascular disease risk. Univariately, habitual moderate-vigorous physical activity is positively associated with brachial FMD in older adults. However, time spent in one physical behaviour inherently displaces time spent in another physical behaviour. The co-dependent impact of free-living physical behaviours on brachial FMD are poorly understood. PURPOSE: Test the hypothesis that replacing sedentary time with physical activity will be associated with a greater brachial FMD using an isotemporal substitution analysis approach. METHODS: Brachial FMD was assessed via duplex ultrasonography in 74 adults (37 females; age: 44 ± 23 years; body mass index: 25.4 ± 4.0 kg/m2). Habitual time spent in sedentary postures, standing postures, light- (LPA), moderate- (MPA), and vigorous-physical activity (VPA) were assessed 24-hr per day via thigh-worn inclinometry (average: 6.1 ± 1.0 days). All physical behaviours were standardized into 30-min units. Isotemporal substitution modelling examined the impact of replacing one physical behaviour (e.g., sedentary time) with another (e.g., MPA) while holding the total time spent in all waking behaviours constant. RESULTS: In covariate-controlled partition models (all variables entered simultaneously), only MPA was independently associated with FMD (β=1.24, CI: 0.01-2.47). Substituting 30-mins per day of sedentary time or standing time with MPA was associated with an ~1.2% higher relative FMD (sedentary: 1.24%, CI: 0.12-2.36; standing: 1.18% CI: 0.05-2.30). Substituting LPA or VPA time with other behaviours was not associated with any predicted change in FMD. CONCLUSION: Theoretically, replacing 30-mins of stationary time (sedentary or standing time) with MPA may be associated with clinically relevant improvements in brachial endothelial function.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| 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".