Is the Response Capacity of Rapid Vasodilation Mechanism(s) at Exercise Onset Sensitive to Exercise Training?
Bibliographic record
Abstract
Resistance vessels in skeletal muscle dilate with the first contraction of exercise. This dilation is proportional to contraction intensity. Whether the mechanism(s) responsible for this immediate, rapid vasodilation can be modified with exercise training is unknown. PURPOSE: We tested the hypothesis that the immediate and peak forearm vasodilatory response to a single, brief forearm contraction would be higher in arm + leg trained athletes vs. leg trained athletes. METHODS: 8 male distance runners and 9 male rowers were recruited from the Queen's University varsity teams. Varsity runners served as a control for whole body training status. Subjects lay supine with the arm extended laterally at heart level and performed single, 1 s isometric handgrip contractions at each of 5 kg, 15 kg, 25 kg and 35 kg contraction force. 3 trials per contraction force were averaged for each subject. Order of contraction force was counterbalanced across subjects. Beat by beat measures of brachial artery forearm blood flow (FBF; Doppler and Echo ultrasound) mean arterial blood pressure (MAP; finger photoplethysmography) and heart rate (HR; ECG) were made at baseline and for 1 min following each contraction. RESULTS: Data are mean ±SE. MAP was not different between groups. Therefore, increases in FBF (DFBF) from rest were representative of the vasodilatory response to contractions. DFBF (ml/min) in the first cardiac cycle post-contraction was not different between groups at 5 kg (P=0.275) or 35 kg (P=0.332), but was significantly elevated in rowers at 15 kg (118 ±19 vs. 84 ±9, P=0.013) and 25 kg (176 ±17 vs. 130 ±13, P=0.038). Peak DFBF (∼3rd - 4th cardiac cycle following contraction) was not different at 5 kg (P=0.967). It was elevated in rowers at 15 kg (183 ±18 vs. 112 ±11, P=0.015), 25 kg (266 ±23 vs. 193 ±21, P=0.005) and 35 kg (333 ±32 vs. 256 ±27, P<0.001). The slope of the peak FBF response vs. contraction force was significantly steeper in rowers than runners (8.6 ±0.9 vs. 5.5 ±0.8 ml/min/kg, P=0.02) CONCLUSIONS: These data support the hypothesis that rapid vasodilatory mechanisms responsible for the onset of exercise hyperemia can be improved with exercise training. This effect can be achieved in young, healthy males and is independent of whole body training status. The stimulus for this adaptation appears to be local to the trained muscle.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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 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".