Control of muscle VO <sub>2</sub> kinetics: a role for metabolic rate?
Bibliographic record
Abstract
Control of skeletal muscle oxygen uptake (VO 2 ) kinetics is mediated by ADP feedback, oxygen and substrate delivery and mitochondrial content. Controversy remains whether mitochondrial enzyme activation at exercise onset contributes to this control. We tested the hypothesis that VO 2 kinetics would be speeded by increased metabolic rate, in pump‐perfused, tetanically‐stimulated muscle (i.e. independent of O 2 delivery and muscle recruitment dynamics). The gastrocnemius of 6 anaesthetized, ventilated dogs was isolated and the tendon attached to a force transducer. Blood flow was pump‐controlled at a constant flow (1.09 ± 0.25 L.kg −1 .min −1 ; mean ± SD). Isometric tetanic contractions (50 Hz; 200 ms duration) were elicited via supramaximal sciatic nerve stimulation. Metabolic rate was manipulated using 3 min of stimulation at 0.33 Hz (S1) immediately followed by 3 min at 0.67 Hz (S2); also following prior contractions at 0.67 Hz and 2 min recovery (PS1, PS2). Muscle VO 2 was determined contraction‐by‐contraction. τVO 2 was lower in S1 (11.4±2.4 s; p <0.05) than S2 (17.6±2.9 s), PS1 (16.6±4.6 s) and PS2 (16.1±2.5 s). Unexpectedly VO 2 kinetics were fastest at the lowest stimulation frequency without prior contractions. This implies that any putative role of mitochondrial activation in VO 2 kinetic control may be countered by a reduction in cellular energy state (e.g. less negative ΔG ATP ). Supported by BBSRC: BB/F019521/1
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 | 0.000 | 0.001 |
| 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 | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".