Brachial artery flow-mediated dilation during incremental handgrip exercise is not impacted by sex or female sex hormones
Bibliographic record
Abstract
Sex differences exist in reactive hyperemia flow-mediated dilation (RH-FMD), with males demonstrating larger RH-FMD responses than naturally menstruating females and females using oral contraception (OC). This difference is thought to be partly attributed to sex hormones. Among females, some studies demonstrate lower RH-FMD in females using OC relative to naturally menstruating females. To date, non-invasive assessments of endothelial function in males, naturally cycling females and females using OC have only been completed using RH-FMD. Notably, due to differences in the shear stimulus during sustained shear-induced FMD (SS-FMD) versus the transient pattern observed with RH-FMD, SS-FMD may provide distinct insight into endothelial dysfunction undetected with RH-FMD. Therefore, we hypothesized that the SS-FMD responses to incremental handgrip (IHG) exercise would be greatest in males, and that females using OC would have the smallest increase in SS-FMD compared to males and naturally menstruating females. The IHG protocol consisted of 3-minute stages of rhythmic handgrip exercise at 15, 30, and 45% of an individual’s maximal voluntary contraction (MVC) force, with no rest period between MVC transitions. Brachial artery diameter and blood velocity were measured simultaneously via duplex Doppler ultrasound in 10 males (26±4 [mean±SD] years), 11 naturally menstruating females (25±4 years), and 9 females using OC (27±5 years) during IHG. Females were tested in the mid-luteal (ML) and active (high hormone) OC phases. SS-FMD and shear rate were analyzed using linear mixed model analyses. MVC was greater in males relative to both groups of females (males: 40±6, ML: 28±8, OC: 26±6 kg; One-way ANOVA: post-hocs P≤0.001). Brachial artery shear rate was not different between males, ML females or females using OC throughout exercise (group-by-stage interaction: P=0.975). Consequently, the brachial artery dilated by 1.3±1.5, 0.1±2.1, and 1.2±3.6 % at 15% MVC, 4.0±3.1, 2.7±3.3, and 4.1±4.8 % at 30% MVC, and 9.1±4.9, 7.3±5.4, and 7.6±5.9 % at 45% MVC, in males, ML females, and females using OC, respectively (all P>0.05). Furthermore, the slopes of the relationship between the change in brachial artery diameter and shear rate was similar between the three groups (Males: 0.0004±0.0002, ML: 0.0003±0.0002, OC: 0.0003±0.0002 Δmm/Δ1·s -1 ; One-way ANOVA: P=0.564). Taken together, these data indicate that endothelial function in response to sustained elevations in shear stress are not impacted by biological sex or OC use. Supported by the Natural Sciences and Engineering Research Council of Canada, and IEEM indirect funds. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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) | 0.000 | 0.001 |
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 teacher head, 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".