Near-infrared Spectroscopy Measures Of Sternocleidomastoid Blood Flow During Exercise And Hyperpnea
Bibliographic record
Abstract
Respiratory muscle work exerts an influence on the distribution of blood flow during exercise. Most studies have focused on blood flow to the locomotor musculature rather than respiratory muscle owing to their complex anatomical arrangement. PURPOSE: To examine changes to accessory respiratory muscle blood flow in response to increasing ventilation (V̇E) during whole-body exercise. METHODS: Blood-flow index (BFI) of the vastus lateralis (VL), sternocleidomastoid (SCM), and 7th intercostal space (7IC) was measured during five-minute bouts of cycle exercise at 30, 60 and 90% peak-power output (EX). Participants then mimicked the hyperpnea of exercise (HYP) achieved during each exercise bout. BFI was measured using near-infrared spectroscopy optodes and indocyanine green. RESULTS: Six healthy males completed this study (age: 26 ± 3 years, V̇O2max: 56 ± 9 mL· kg-1· min-1). V̇E was matched well between EX and HYP (EX-30%: 53 ± 10 vs. HYP-30%: 56 ± 14; EX-60%: 86 ± 14 vs. HYP-60%: 87 ± 18; EX-90%: 159 ± 31 vs. HYP-90%: 142 ± 40 L· min -1, all p > 0.05). BFI-VL increased from 0.15 ± 0.09 μM·second-1 at rest to 2.57 ± 1.10 μM·second-1 during the EX-30% trial and 0.44 ± 0.23 μM·second-1 during the HYP-30% trial and did not significantly increase thereafter in either condition. No interaction effect was observed between condition and intensity, however, BFI-VL was significantly greater in the EX trials compared to the HYP trials (p < 0.05). BFI-SCM increased slightly from 0.87 ± 0.48 μM·second-1 to 1.01 ± 0.54 and 1.67 ± 1.54 μM·second-1 in the EX-30% and HYP-30% trials respectively. We observed no effects of condition or intensity when measuring BFI-SCM (p > 0.05). At rest BFI-7IC was 0.84±0.59 μM·second-1 and in the EX-30% and HYP-30% trials increased to 1.20 ± 0.75 and 1.26 ± 0.60 μM·second-1, respectively. No differences in BFI-7IC were observed between condition or intensity (p > 0.05). CONCLUSION: Previous studies have shown that during heavy whole-body exercise there exists a competition for blood flow between the locomotor and respiratory muscles during heavy, whole-body exercise. In this study, BFI-SCM was similar between exercise and hyperpnea mimicking trials across a range of ventilations, suggesting blood flow to accessory respiratory muscles is preserved during exercise. Funding: NSERC
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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 | 0.000 | 0.000 |
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".