Slower Pulmonary VO2 and Muscle Deoxygenation Kinetics in Knee-Extension Compared to Cycle Ergometer Exercise
Bibliographic record
Abstract
PURPOSE: VO2 and muscle deoxygenation kinetics during the transition to mo derate-intensity knee-extension (KE) and cycle ergometer (CE) exercise were examined in 5 healthy young adults. METHODS: Subjects performed repeated step-transitions to 90% estimated lactate threshold in either CE or alternate-leg KE). Step-transitions were 6 min in duration and were preceded by 6 min baseline exercise (∼5W). VO2 was measured breath-by-breath by mass spectrometer and volume turbine. The change in deoxyhemoglobin/myoglobin (HHb) concentration was measured continuously by near-infrared spectroscopy (NIRS; Hamamatsu NIRO 300). Individual HHb trials were analyzed to determine the time delay prior to an an increase in HHb (HHb TD) following the onset of exercise (determined as the time to the first point corresponding to a consistent increase above the nadir of the NIRS-signal). VO2 and HHb data were filtered, time-aligned and ensemble-averaged to 5 (HHb) and 10 (VO2) s averages and fit with a monoexponential curve using nonlinear regression techniques. VO2 data were fit from the phase 1-phase 2 transition to the end of exercise and HHb data were fit from the HHb TD to 120 s. RESULTS: tVO2 was shorter (p <0.05) in CE (23 ± 9 s) than KE (34 ± 12 s). There was a greater (p <0.05) baseline VO2 in CE (0.65 ± 0.05 L/min) than KE (0.58 ± 0.02 L/min) and a greater amplitude (P <0.05) in CE (1.02 ± 0.20 L/min) than KE (0.61 ± 0.17 L/min). The gain of the VO2 response (DVO2/DWR) was lower (P <0.05) in CE (9.9 ± 0.6 L/min/W) than in KE (12.9 ± 1.9 L/min/W). The HHb TD was shorter in CE (10 ± 1 s) than KE (14 ± 3 s) while the tHHb (CE, 8 ± 3 s; KE, 17 ± 12 s) and HHb MRT (HHb TD ± tHHb) (CE, 18 ± 3 s; (KE, 31 ± 13 s) tended to be lower in CE than KE. CONCLUSION The greater HHb TD and HHb MRT which accompanied slower VO2 kinetics in KE compared to CE suggests that O2 delivery, relative to O2 consumption, was greater and/or faster in KE than in CE. (Supported by 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 | 0.001 |
| 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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".