EVIDENCE FOR RAPID VASODILATION IN TRANSITION FROM MILD TO MODERATE EXERCISE INTENSITY
Bibliographic record
Abstract
Debate continues regarding the contribution of muscle pump vs. vasodilation to the “immediate” increase (first second following initial contraction release) in blood flow at the onset of exercise. Furthermore, studies have exclusively focused on this issue in the context of rest-to-exercise transitions. PURPOSE To test the hypothesis that there is an “immediate” vasodilatory contribution to the increase in blood flow in an exercise-to-exercise transition. METHODS 7 healthy young volunteers (2 female, 5 male) lay supine with the forearm elevated above heart level. In this position, veins are virtually empty and no additional contraction-induced venous emptying occurs in either rest-to-exercise or exercise-to-exercise transitions (i.e. muscle pump is ineffective). A step increase from rest to 3 min of mild (10% maximal voluntary contraction, MVC;R-10step) rhythmic, dynamic forearm handgrip exercise (1-s contraction/2-s relaxation duty cycle) was followed by a further step to moderate (20% MVC; 10-20step) exercise. Beat-by-beat measures of brachial artery diameter and mean blood velocity (MBV; Doppler ultrasound), heart rate (HR; ECG) and arterial blood pressure (ABP; arterial tonometry) were performed. RESULTS All data are mean ± SE. HR and ABP did not change during the first few seconds of each transition. Forearm blood flow (FBF) increased following release of the initial contraction in the 10-20step by the same absolute amount as the R-10step, despite no gain in muscle pump effectiveness (Δ FBF: R-10step: 52.2 ± 12.3 ml/min vs. 10-20step: 63.5 ± 13.7 ml/min, P = 0.65). These values represent a different % Δ (R-10step: 126.3 ± 25.6% vs. 10-20step: 20.3 ± 5.2%, P = 0.001). CONCLUSION These data support the hypothesis that there is an “immediate” further vasodilation in exercising muscle in an exercise-to-exercise transition. The mechanisms responsible remain to be determined. Supported by NSERC; CFI New Opportunities Fund.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".